How to water cannabis plants in hydroponic systems ?

Bud flowering in coco coir
Bud flowering in coco coir

How to irrigate cannabis in hydroponic systems?

Marijuana is a plant that adapts very well to changes, we can choose any of the different growing media on the market to easily grow it. The most common methods of cultivation are; soil and hydroponic systems - an inert substrate like coco coir, clay pebbles, rock wool or mapito - without forgetting the aeroponic systems, a growing method which is now increasingly used.

Between the different hydroponic and aeroponic growing systems we can find clear differences among the used substrates, although they are all inert. We will have to keep in mind all these differences when setting up our growroom. The fertilisation or fertirrigation in hydroponic systems will vary depending on the chosen system. Then, how to know what is the best way to fertilise our plants according to each system?

We'll start discussing each substrate separately and analyzing their virtues and faults, so that each grower can easily choose between his/her favourite hydroponic growing system and understand its functioning, advantages and disadvantages.

Growing Marijuana in Coco Coir

Coco Coir, as it’s well known, is an organic substrate from the fibre that surrounds the coconuts, the fruits of the coconut trees. After being processed and treated, it will be suitable for growing marijuana or for other agricultural uses. The commercial coco coir that we find for growing marijuana usually has a granulometry - thickness of the coconut fibres - quite appropriate for a balanced retention and evaporation of the humidity.

Growing hydroponics in coco coir
Growing hydroponics in coco coir

This ability to retain the humidity but not the water makes the substrate being always - or almost always - oxygenated, preventing the roots to suffer in case of over-irrigation. Moreover, when periods of drought occur, the roots aren’t compressed with the substrate, because when the coco coir dries it has almost no density and doesn’t compress the roots, keeping them more protected than with other substrates.

In this case, coco coir won't compact as it happens with the soil - which compresses the roots and is difficult to hydrate again - or in aeroponic growing systems ; in case of a failure in the irrigation system the roots will dry and the plant will be dead in a few hours, depending on the ambient humidity level of the rootball.

Plant grown in coco coir
Plant grown in coco coir

The advantages of coco coir in this case are more than proven; when the plant is dried and dehydrated it recovers much faster than the same plant grown in soil in the same  conditions. The damage caused by dehydration are very reduced compared with those caused on soil, since the recovery of the plant is much slower than using coco coir. Therefore, the use of coco in hot countries like Mexico is very extended to prevent problems associated with drought.

During the growing of marijuana plants in coco coir, the irrigation will vary both in dosage, quantity and concentration of the EC and PH levels. In the first stage of the plant's life we will try to take advantage of the already mentioned characteristics of the coco, performing a manual irrigation with a little amount of water to create a humidity period followed by another of drought, making the roots of the plants or cuttings to expand in search of the humidity on the sides of the pot.

The amount of water depends on the size of the pot; in this case, you can use from 10 to 15% of the capacity of the plant's pot to water it, so it gets dry relatively fast and we can irrigate again with the same amount of ml/day.

During the first weeks of growing - and until the second week of flowering - you have to gradually increase the amount of nutrient solution as well as the EC levels, always keeping a balance between the different nutrients. Once the second week of flowering has passed, you can choose to use a simple automatic irrigation system with a tank - which you'll use to mix the nutrient solution - and a water pump to irrigate all the plants during a period of a week.

This automatic irrigation system will also vary in quantity and concentration as the flowering period goes on; we can use a simple digital timer with 8 on/off programs to modify the duration of the irrigation period at our own will.

Coco Coir will help you to know how many irrigations you can provide to your plants before they suffer by an excess of humidity. You can perform as many irrigations as the speed of the drying process of the substrate allows you. For example, if you make 3 irrigations per day, the substrate should be about 30% to 50% dried before watering again. In the last weeks of flowering, you can reduce this humidity range to provide all the necessary nutrients for an abundant flowering and, on the other hand, make a root flush to evacuate the nutrient wastes in the substrate as well as to facilitate the loss of nutrient reserves in the marijuana plants.

It’s easy to detect when the coco coir dries, given that this substrate change its colour. It acquires a light brown colour when it is dry, while showing a dark brown when it’s wet. At the end of the flowering phase it won’t be necessary to have this drought period because the plant is trying to feed and finish ripening.

Last stage of growth on coco, PH 5.9 and EC 1.4, 3 irrigations per day
Last stage of growth on coco, PH 5.9 and EC 1.4, 3 irrigations per day

If our cannabis plants have been well fed, at the end of the crop they won’t need more nutrients and it’s possible to irrigate without fertilisers to leave the plants free of reserves, achieving a final better taste and smell of the buds. During this final phase - two last weeks before harvest - you can continue using vitamins, amino acids, elicitors, enzymes, or any other product that facilitates the plants to spend their reserves of nutrients. You can observe how the colour of the leafs changes from an intense green to a pale yellow as the plant loses its nutrient reserves.

EC levels will vary according to the number of irrigations applied to the plants. The coco coir has the ability to retain an optimal amount of nutrients through its fibres, so that the more irrigations you make, the lower should be the EC, because the plants will have a greater availability to feed. Indica cannabis plants can be irrigated with an maximum EC level of 2 - 2.2 in those weeks in which they require more nutrients; for this type of plants, this period is usually during the 6th and 7th weeks of the blooming phase in the case that they have a total flowering period of 8-9 weeks (according to the grown genetics). You should use high EC levels only in the case of making few irrigations per day or making only a manual irrigation if you don't have an automatic watering system .

Growing marijuana seeds in coco coir
Growing marijuana seeds in coco coir

If you have an automated irrigation system and perform a greater number of irrigations per day during the flowering stage, you can lower and set the EC level at a maximum of 2.0, always checking the plants. If you observe that everything is fine, you can maintain this EC level during the following weeks, or otherwise reduce it in the case that you see that the plants are saturated.  It should be noted that cannabis strains have different EC level tolerances, so that some strains may show sympthoms of over-feeding while others may require more nutrients when using the same nutrient solution for both of them.

The most efficient way to grow hydroponic marijuana is using a single strain, so we have a homogeneous crop. In the case of  growing more than one strain, it's advisable to choose varieties belonging to the same family - as happens with the Blue, White, Kush and Afghan families - or which by default are similar in their growing features, considering their vigour, flowering time and acceptance of nutrients.

Basic growing diagram in COCO COIR

Basic PH and EC growing diagram
Basic PH and EC growing diagram

* EC= Depending on the condition of the plants you can use an EC level or another. You can even maintain the EC value of the previous week if you observe that the plants are very loaded with nutrients.

* PH = the Ph level can fluctuate, it can be reduced to 6.0 and allow it to reach a  6.2 or 6.4 value, when we will reduce it again to 6.0 and irrigate with a suitable PH for the plant.

Marijuana growing in hydroponic systems

Marijuana grown in clay pebbles
Marijuana grown in clay pebbles

Hydroponics is one of most diversified growing methods for cannabis cultivation; there are many and different hydroponic systems, but all have a basis in common.  All you have to do is to adapt the type of irrigation according to your hydroponic system and your substrate.

The basis of hydroponics is simple: it's based on providing nutrients to the plants through fast-absortion chelated fertilisers in an inert substrate like rock wool, clay pebbles, mapito etc…

By using a growing system of automatic irrigation - either recirculation or non-recovery systems - marijuana plants are perfectly fed. If we use clay pebbles, it's very important to stabilize the PH of the substrate to prevent any kind of problem with the PH during the cultivation. If this stabilization of the PH  isn’t done, the plants will live in an unstable environment with many difficulties to absorb nutrients. Moreover, in recirculation systems we may find an imbalance in the nutrient solution tank caused by the PH of untreated clay pebbles, which causes nutritional deficiencies on marijuana plants.

In recirculation systems - where the nutrient solution is always entering and leaving the tank  to make its closed irrigation loop - the Ph and EC levels can be easily altered by impurities from a dirty or unstabilized substrate. In non-recovery systems these factors are also altered but in a lesser degree, and are easier to control given that the solution used for watering our plants doesn’t return to the tank and thus can't modify its initial composition.

It’s important to point out that in this growing system the roots are very exposed to the air, with a direct dependency on a constant humidity to develop without problems. As soon as the roots suffer stress from a lack of humidity they will be seriously affected, since they don't have any protection system as happens in the case of coco coir, where the rootball is less exposed to the air and dries out much slower than in clay pebbles, where the air is introduced with more ease. On the other hand, if these factors are under control and we don't make any mistake, the growth of the plants in this kind of systems is explosive.

The irrigation methods in these growing systems vary greatly from one to another; we can find systems like the Dutch Pot Hydro , in which William from GHE recommends a constant 24-hour irrigation. There will be growers who prefer to schedule a few irrigations per day with a timer, watering every 15 minutes. Others may prefer a 15-minute irrigation for each hour. According to the chosen system we must set the correct irrigation program, as happens in the case of growing in rock wool slabs.

In these cases it’s important to remember that each grower must find out the ideal irrigation time for his/her growing space, because it will always vary depending on several factors - temperature, humidity, ventilation, air renewal,... - that will make the substrate to dry out faster, so we'll have to  make more irrigations always adapting the EC level according to the present week and the needs of the plant.

In these hydroponic systems, the nutrition of the plants is more effective than in coco coir or soil. We should lower a few points the maximum EC levels and ckeck the plants everyday to find the optimal EC  for each strain.

Growing diagram in CLAY PEBBLES

Growing diagram for hydroponics
Growing diagram for hydroponics

* EC= Depending on the condition of the plants you can use an EC value or another, you can even maintain the EC of the previous week if you observe that the plants are very loaded with nutrients

* PH = the Ph can fluctuate, it can be reduced to 6.0 and allow it to reach a 6.2 or 6.4 value, when we will reduce it again to 6.0 and irrigate with a suitable PH for the plant.
*(2.0) = Depending on strains

Growing Marijuana in Aeroponic Systems

Aeroponics is the evolution of the hydroponic systems; the main difference between them is that, in aeroponic systems, the roots are suspended in the air without any physical sustenance. As they haven’t a substrate in which to grow and maintain the humidity for the roots, the irrigation will be different from hydroponic growing systems that have a physical sustenance.

Marijuana growing in an aeroponics system
Marijuana growing in an aeroponic system

Aeroponics has, like any other growing system, advantages and disadvantages. In this kind of setup,  any mistake can be observed very quickly in the plants; in these growing systems cannabis plants detect rapidly all feeding and environmental changes, since they don't have any physical buffer to maintain constant PH and EC levels.

PH and EC Meters
PH and EC Meters

If the PH, the EC and the humidity in the root system isn’t extremely controlled within logical growing parameters, plants won’t grow or bloom as they should. Otherwise if you have an exhaustive control of all the factors that affect the development of your marijuana plants, you can get very abundant harvests of first quality buds. You will also enjoy the advantages that accompany these growing systems, such as the vegetative speed and the yield of the cannabis plants, which is really impressive.

Plants grown in these type of systems may reduce up to 3 weeks (or even more) the period of growth than plants grown in soil. This fact is based on the non-existence of the substrate. There is no resistance for the roots to develop so they can grow and expand as long as they are fed with a good  fertiliser in the right amounts.

It should be mentioned that, in these aeroponic systems, the oxygenation, temperature and renewal of the nutrient solution must be controlled at all times, as well as the correct EC and PH levels. A high temperature of the nutrient solution can create fungi in the roots, decreasing the absorption of nutrients by the plant, since the oxygenation of the water will be much lower and fertilizers will also be less effective.

If in hydroponic growing systems the nutrition of plants is very fast and requires minor EC levels than in soil or coco coir, in the case of aeroponics it happens with even more difference. In this system the roots receive micro-particles of water that adhere to the roots, which causes a very rapid absorption of the available nutrients. This fact makes that plants grown in aeroponic systems require a lower concentration of nutrients than in other growing media.

Growing diagram in AEROPONICS

Basic growing diagram for aeroponics
Growing diagram for aeroponics

* EC= Depending on the condition of the plants you can use an EC value or another, you can even maintain the EC  of the previous week if you observe that the plants are very loaded with nutrients

* PH = the Ph can fluctuate, it can be reduced to 6.0 and allow it to reach a 6.2 or 6.3 value, when we will reduce it again to 6.0 and irrigate with a suitable PH for the plants.

The Nutrient Tank

Foldable Nutrient Tank
Foldable Nutrient Tank

The nutrient tank is an important point to keep in mind because it’s used to irrigate all the marijuana plants of the growroom. If you buy a hydroponic system, this already includes a tank to irrigate the specific number of plants recommended by the manufacturer. Otherwise, if you want to grow in coco coir, expanded clay, or mapito in plant pots you have to consider the number of plants to grow in order to fill the tank with the necessary reserves of nutrients for one week.

In the case of non-recovery growing systems - systems without recirculation of the nutrient solution- you will have to calculate the size of the tank according to the number of plants you're going to grow and the maximum dosage of irrigations to realize. If you grow a SOG using 30 plants per m2 with a maximum of 8 irrigations per day - 1-minute duration - with a dosage of about 40 ml per minute you will need a tank of about 70-80 liters.

If instead of a SOG you want to grow a SCROG, you can calculate the maximum irrigations per day and pot taking into account the volume and the amount of pots to irrigate. You can use a digital timer with multiple programs to suit the irrigation to the needs of your crop.

How to calculate our tank capacity:

(Number of plants) x (Number of irrigations per day) x (Dosage per irrigation) = Litres per day.
(Litres per day) x 7 days = Litres per week

Example for SOG crops:

(9,6 L/day) x (7 days) = 67,2 L/week + 10 Litres of reserve for the pump = tank of 80-90 Litres (since you won't fill it up completely)

Example for SCROG crops:

(6 plants/m2) x (8 irrigations) x (10-15% of the pot size (11L) in L/day) = 7,92 L/day
(7,92 L/day) x (7 days) = 55,44 L per week = ideal tank size of 80L

Temperature and oxygenation of the nutrient solution of the tank

As mentioned before, you should carefully check and monitor the tank and its nutrients, because this is the source that provides the plants with a good feeding, and taking care of it will spare us from several nutritional issues that are common in marijuana plants. On first place you should make sure that the fertilisers used are chelated and specific for growing on coco coir or hydroponic systems. If you use any biological fertiliser, your plants won’t be able to properly absorb the nutrients as they should, so their yield will be seriously diminished.

Natural oxygenation of the water
Natural oxygenation of the water

There are lots of fertilisers or supplements for fertilisers that are 100% organic, but they’re chelated with amino acids for an optimal absorption of nutrients - as in the case of Aptus fertilizers. There are many other fertilisers for growing in hydroponic systems, but in most cases the chelated form is mineral and not amino acid chelated.

Dosing correctly the fertilisers in the tank is also very important, because it’s always better to follow a logical order for an exhaustive control of the nutrient solution. First, you should put the base fertiliser. The dose is usually from 1 to 2. 5 ml per litre of water according to the growing period in which the plant is, starting with the lowest dose and gradually increasing it until the recommended maximum dose is reached (depending on the concentration of the used fertiliser). The next step is to add the stimulants, amino acids or other components such as bacteria or mycorrhizae.

Marijuana roots in an aeroponic system
Marijuana roots in an aeroponic system

The last step is adjusting the PH level. After that, you can already irrigate all plants with this nutrient solution. As the hours pass, the PH level will gradually rise, so you will have to lower it again before watering your plants again. As we have already mentioned before, you can allow a small fluctuation of the PH level before lowering it the next day with any citric acid or PH down solution. If you use an automatic irrigation system, it’s convenient to lower it just before turning on the pump; in this way, every irrigation will be with a different PH level within the optimal range, to absorb all the nutrients needed for a better plant development.

Another important point to keep in mind is the temperature of the nutrient solution in the tank. The temperature is always directly related to the level of oxygen in a nutrient solution. A higher temperature means less oxygen in the water, so an optimal temperature is between 18 and 22 degrees Celsius. This mentioned temperature intervals will be the most appropriate in order to maintain constant and adequate levels of oxygenation in our nutrient solution, to facilitate the feeding of the plants and the maintenance of the nutrients in the tank.

Aeroponic marijuana crop with LED lights
Aeroponic marijuana crop with LED lights

H2O Temperatures vs Oxygen table

To improve the oxygenation of the tank, in addition to have the temperature controlled, you can add an air pump connected to a non-toxic silicone tube and a diffuser stone to spread out the oxygen in small bubbles, keeping the nutrient solution properly oxygenated.

Oxygen dissolved in water according to temperature
Oxygen dissolved in water according to the temperature

A high temperature will negatively affect all marijuana crops, being more harmful firstly in aeroponics, hydroponics, coco and soil. The reason is simple; in the first two growing systems the water is the main live sustenance and the root system is much more unprotected. In the case of coco coir and soil this factor is also important although our plants will have a greater resistance to a high water temperature, since in these substrates the roots are more protected than in hydro and aero systems.

The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.

Comments in “How to water cannabis plants in hydroponic systems ?” (20)


Rod 2021-06-26
I'm a new grower and 6 time cancer survivor. I have 3 and a hafe gallon grow oxygen pots in my indoor room I can find any wear to tell me how much water and nutrients to ad to them .so I ad a mixture of 1 gallon of water With fertilizer mixed to according to 1 gallon of water and nets. Per plant they seem to b doing fine I doing this righ????? I'm open 4 help

Alchimia Staff

Tim Alchimia 2021-06-28
Hi Rod, thanks for your comment and question. The oxygen pots that I've seen are flood & drain systems, connected to a reservoir and a pump & controller which periodically irrigates and drains the oxygen pots so the amount of irrigation time can be adjusted according to conditions and the stage of the life cycle that the plants are in at any given moment. Is that how your system works, or are you hand-watering these oxygen pots? If things are going well and your plants are happy then you must be on the right track! If you are hand watering then the only thing I'd advise is to take great care not to overwater as this could easily cause root fungus issues very quickly - it's vital that the root zone has enough oxygenation. I hope that helps, but maybe with a bit more information, we could help you more. Best wishes and happy growing!


headsmess 2019-06-09
so far i have best results with a cross between aeroponics and flood/drain system... big drum of nutrient solution, pump inside constantly running, simply circulating water with a venturi to suck in some air for oxygen. some of the pumped water goes off to the growing reservoir. which is PVC pipe with lil basket pots pushed in holes drilled along. a neat little bell syphon stuck in at one end. basically floods about every 3-4 hours depending on the flow rate, drains itself then repeats. if my pump will survive a day or two as its never completely dry. water in tank stays crystal clear... just check the levels every few days. as for results...theres a reason i stick with this system!

Alchimia Staff

Tim Alchimia 2019-06-10
Hi headsmess, thanks very much for your contribution to our blog, it's really appreciated. Sounds like a pretty failsafe system you've got there, nice work! All the best and happy growing!


alex 2018-10-09
hi I have ebb and flow i have about 270 bucket and I feed then with two separate 275 gallon reserver water I notice some of my plant leaf starting to yellow my ph between 5.8 to 6.4 and etc is 1.8 and watering its 4 time a day I must add fill and drin take about 2 hours because of number of pot , any idea about that

Alchimia Staff

Tim Alchimia 2018-10-11
Hi Alex, thanks for your question. If your plants are still in veg then we'd recommend lowering that pH to 5.5 which should help solve the problem. If they're in flower and it's the lower leaves turning yellow then it sounds like it could be a Nitrogen deficiency, which is fairly normal depending on the genetics, so you'll need to raise the EC a bit to compensate. Any more info you can give us about the plants and what stage they're at would be a great help, thanks again and happy growing!


Bob 2018-07-15
Hello, I grow on an ebb and flow tables in pebbles, using 6ltr pots. How deep should I fill the pebbles before I put my plants in? If you could help that would be great. Cheers


shumitz Is an Alchimia client 2018-06-14

Alchimia Staff

Dani Alchimia 2018-06-18
Hi schumitz, I think I know what you're talking about. Plants developing tons of resin but buds not fattening at all. I've seen that a few times, always indoors and with really low minimum temperatures. Did your plants have low temps? The roots perhaps? It is something similar to spring crops, more leafy, with less bud but awesome resin production, right? Here you have an example of what I mean. Talk soon!


Shumitz Is an Alchimia client 2018-06-09
Hey nice info (sorry i´m not english ) I just tried the aeroflo14 from ghe, i´m about to harvest and im so disappointed, I sure made some mistake but can´t understand what, they grow beautiful no issues or signs of bad feeding, beautifull leave colors, ec ph controled. the problem was no bud grow, they got so small and slim yet full of crystal. Damn cant figure it out. I am watering every 15 mt I dont if its right, another thing i´m not sure its, at some point in early stage the roots get submerse in the (2)tubes cause the pipe of outflow to the tank its high so the roots are always under water. It can be some light leakage, but i dont know Any thoughts


Tim 2018-05-21


Tim 2018-05-21
Meant the rockwall is always set ads our roots


Tim 2018-05-21
I grow in nft tanks with astounding results but always turn my water pumps of while I sleep 5 0r 6 hours the to us all is always set as ate roots I don't think this hurts them in anyway they prob don't no lights of anyway aye cheers Tim

Alchimia Staff

Tim Alchimia 2018-05-28
Hi Tim, thanks for your comment and question. I'd say that's fine, as long as the rockwool doesn't dry out while you're sleeping, which may not be the case now but as summer approaches temperatures will rise and as they grow bigger the plants will want to drink more! Just keep a close eye on the situation and I'm sure you'll be fine. all the best and happy growing!


Tim 2017-06-09
Hi there I got a problem hope someone can with o started 6 seeds and they all piped really.quick overnight I root riot plugs now there in 3 inch rockwall cubes but they got loads of roots coming out the bottom .but the trouble is I can't put them into my nft for a week or 2 cause it's occupied by previous tenants . Any help be good thanks

Alchimia Staff

Dani Alchimia 2017-06-12
Hi Tim, Roots coming out of the rockwool cube will probably dry out and die, although it shouldn't represent a problem. As long as your plants are properly watered, they'll keep on growing until you can put them into your nft system. If necessary, you can even prune the roots when transplanting. Hope it helped!


John 2017-04-10
Hi Dani My plants are 9" tall and my leaves are starting to turn yellow at the top of my plant. Other than that, the plants are very healthy. I'm doing a flood to drain system and nut sure how often and how long I should water them. I'm using Flora Grow. Thanks for your help

Alchimia Staff

Dani Alchimia 2017-04-10
Hi John, When plants need nitrogen to produce new shoots and they can't find it, they normally take it from the older, lower leaves of the plant. Thus, if there was a deficiency of nitrogen you'd see the older leaves turn yellow. When younger leaves turn yellow, the problem is more likely to be related with iron deficiencies. Notice that Flora Series nutrients must be used together by mixing Flora Gro, Flora Bloom and Flora Micro in different proportions according to the stage of the plants. If you're only using Flora Gro your plants may need other elements. Hope it helped!


Tim 2017-02-22
Where's my post gone ???

Alchimia Staff

Dani Alchimia 2017-02-24
Hi Tim, I've replied your comments on the article about SOG. Can't find any other comment from you! Best!


Tim davis 2016-12-22
Hi good people of earth. Just set up hydro tent.hav 12 clones.also wondering about h2o schedule. About 2 to 3 mins? 2 to 3 times a day? HOW LONG SHOULD THEY SIT ? In the the h2o?

Alchimia Staff

Dani Alchimia 2016-12-22
Hi Tim, Your plants will need more water and nutrients as they grow. If you're using clay pebbles, I'd start with 5 waterings per day (3-4 minutes each). As your plants start developing buds, they'll need more nutrients and water, so you can increase the number of irrigations and their duration. On the other hand, if you're using coco coir you can start with 2-3 waterings (1-2 minutes each) and gradually increase the amount of water and irrigations as the plants develop. Hope it helped!


Antonio Prates 2016-05-20
Very deep article but.....doesn´t say exactly how many times a day should I feed .

Alchimia Staff

Dani Alchimia 2016-05-23
Hi Antonio, Watering frequency mostly depends on the chosen substrate and the growth state of the plants. In coco coir, you can water your plants 2-3 minutes 2-3 times a day (always with the lights on). As your plants get bigger, you can increase either the waterings or their duration. The same happens with any other hydroponic substrate, although normally you'll have to water your plants more frequently if using rockwool, clay pebbles, etc. Hope it helped!


Julian Sami 2016-02-25
HELP!!! I guess my first mistake was to start off with a DWC hydro system. But being a reasonably intelligent person who can read and follow directions I thought that I should be able to do it. Boy seems that I was wrong. On my first try I believe that it was my inability to keep the pH level down that caused the loss of my seeds. they germinated but never grew past that. Now I'm on my second attempt and though my pH is now steady seems again that my seeds (which I germinated using the soaking overnight method and once I saw the tap root pop out of the shells I carefully put them in rinsed and soaked with pH'ed water rock wool and put in the system) are not growing. It's been a week and when I went to change the water I looked at one of the seeds inside the rock wool and it hasn't grown at all. Any suggestion?

Alchimia Staff

Dani Alchimia 2016-02-26
Hi Julian, Seems like you should check the moisture level in your rock wool cubes. They should be moisturized but not completely saturated, otherwise the seeds won't grow. If you find the rock wools too wet, you can germinate your seeds first in your rock wool cubes and once they have sprouted and you have small seedlings put them in your DWC system. Are you using nutrients already? If so, what EC level? I guess your pH level is around 5.5-6.0, am I correct? We have to find a solution Julian! ;)


Erick Is an Alchimia client 2015-09-07
hi, i'll be starting an irrigation system so I was wondering how much water do I need for 3 plants and how often should I change the water with the nuts, thanks in advance.

Alchimia Staff

Dani Alchimia 2015-09-08
Hi Erick, You'll have enough with a 20-30L reservoir, unless you are using really large pots. The ideal would be changing the nutrient solution once per week (if you still have NS on the reservoir, you can add a bit of water and use it to water other plants, you don't need to throw it away). Always make sure that your water pump is completely covered with water, otherwise it can overheat. Hope it helped!


Fernando Enc 2015-06-29
Hello, I am about to set an anto-watering system for my florering-to-be plants in 10 gallond pots of mixture coco/soil, I was thinking of 4 irrigations per day, so should I calculate 15% per irrigation this way too ?? (instead of 8 irrigations of 1.5 gallons that seems too much, for example ). By the way my lights are 360/leds panels, and temp is around 24° C. Thanks!!

Alchimia Staff

Dani Alchimia 2015-07-03
Hi Fernando, 15% should be enough. Always keep in mind that, the bigger the plant, the more water it needs, so you can be sure that your plants will need much more water at the end of flowering that during the pre-flowering stage. Check your substrate and increase the number of irrigations - or the amount of water per irrigation - if necessary. Thanks for your confidence, Best vibes!


Karin 2014-12-11
This all seems really complicated. Is there not a single tool that can measure, monitor and control this all for me?

Alchimia Staff

Dani Alchimia 2014-12-12
Hi Karin, We have a wide range of hydroponic and aeroponic systems (either single pots or multi-pot kits). We also offer you many pH and Ec meters , from the basic ones to systems that automatically regulate these values. Using this systems makes everything much easier, since almost everything is automated. The only thing you have to do is preparing the nutrient solution every 7-10 days, and monitoring the temperature and humidity level of the growroom (which can also be done automatically using thermostats and humidity controllers) . It may seem complicated at the beginning, but growing hydroponically is much easier than any novice would think. Best vibes!


Varmint 2014-11-06
Great info, just started a year ago using coco and love it. Worked in Grandparents greenhouses growing up and was married to an agronomist but have only been growing weed for about 3 years. I've experimented with all types of growing (soil, dwc, hydro in rock wool, mapito, aero). This is by far the best hobby I will ever have and at the present want to master the art in growing in coco. I averaged 175 grams growing Blimburn northern auto in coco. I reintegrate my thanks to you for all the info you have shared with us, Peace

Alchimia Staff

Dani Alchimia 2014-11-06
Hi Varmint Yours is the type of comment why we are making this blog. We are so happy to know that we are helping you! As you said, this can be a hobby that can last a whole lifetime. I myself find it very hard to explain with words the passion I have for growing cannabis. Have you ever tried automated feeding with coco? Should do it, results are awesome. It basically consists in a setup like this one. Thanks for your confidence, Best vibes!


Eric Smith 2014-10-13
I am very aware about the water cannabis plants in hydroponic systems. Good informative article.

Alchimia Staff

Dani Alchimia 2014-10-15
Hello Eric, Thanks for your kind comment, we are always trying to give the best information available to our readers. Best vibes!

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