How to lower the PH in an easy, cheap or homemade way

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Image of a giant marijuana plant, on one side a man climbing up a ladder and on the other side a man below with a pH lowering device.
Image of a giant marijuana plant, on one side a man climbing up a ladder and on the other side a man below with a pH lowering device.



One of the first problems we face is how  cannabis growers for self-consumption, is to reach an adequate PH for the irrigation water or the substrate in which our plants eat. But this will no longer be a head warming for you, because in this post we will look at different ways to lower or even raise the PH so that you have all the correct parameters.



⚠️ PH Does acid increase or decrease PH?



The acid lowers the PH, in fact this action is also called water acidifier, because the PH differs between more acidic and more alkaline. The neutral PH of water is 7.0, the lowest or most acidic point is 0, and the highest or most alkaline point is 14.

But you need to know that not all acids are good for lowering PH, because there are some. some that are very abrasive or can be toxic to our favorite plants when used in high quantities.



👾 How to lower the pH of the water?


The most normal thing is to use phosphoric or nitric acid to lower the PH of the irrigation water, since they are very cheap and with very few quantities you can get quick results. There are 4 types of acid that are often used to lower the hydrogen potential (PH) but not all of them act the same, so I recommend that you take their differences into consideration.

Below you can see a table that shows the 4 acids most used to lower the PH of water, with the percentage of active ingredient that each of them has:


Acid  % Ingredient active
Phosphoric acid  75%
Nitric acid 67%
Citric acid 50%
Ácido sulfúrico 35%



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🧐 How to lower the PH of water with phosphoric acid?


Phosphoric acid is commonly used to lower and stabilize the PH of soft drinks such as Coca-Cola. It is also the type of acid most used in marijuana crops, yes, the typical “PH-” that is sold in grow shops, because thanks to the amount of active ingredient it contains, it takes very little to lower several points of irrigation.

It is important to know that phosphoric acid must be used after adding all fertilizers and additives to the water irrigation, because these products can also cause fluctuations in the pH of the water. Once all the products have been added, the PH is checked with a meter or a drop test, then the phosphoric acid is added little by little until the ideal PH is reached for each stage of the crop.



🎯 How to lower the PH of water or soil in a homemade way?


At home you have some products that can be used to lower the PH of water or soil very economically, although it is true that they are not as effective as those sold for this mission, but for a given moment it can get out of trouble.

The most used are vinegar or lemon, since the former contains acetic acid and the latter is rich in citric acid. If you use lemon it will be a bit more expensive, but from our point of view it is better, because the vinegar is not very stable and causes a greater fluctuation in the irrigation water.

To lower the PH of the soil it is sufficient to carry out several irrigations with a PH lower than the corresponding one, so that gradually that of the substrate also decreases. To check the PH of the soil you can use a meter that is introduced into the soil, but another way to know if it has the correct parameters is to measure the drainage water that comes out of the holes in the bottom of the pot.



🔥 How to lower the pH of water with vinegar?


In this case it is used like any liquid or acid used for this purpose, although much more is needed than when using nitric or phosphoric acid. The ideal is to check the pH of the water first to see if it is too high, and from there add the vinegar a little at a time until you reach the desired point.

It is advisable to consume all the nutrient solution that has been corrected with vinegar, because as I said before it is a bit unstable and after a while the PH rises, so it should be adjusted again.



✅ What if the PH is low?


The biggest problem of having a low PH or irrigation of the substrate, nelle marijuana crops, is that the plants can not assimilate the nutrients available to them, so they can appear deficiencies or blocks of nutrients.

In crops where the soil is used as a substrate, the most important thing is to always maintain an adequate pH in the soil, as this is where the roots must absorb nutrients. The problem is that if the irrigation water is too low PH, it will gradually decrease the PH of the substrate.

In other cultivation systems such as coir, hydroponic or aeroponic among others, it is essential to adjust the PH before irrigation, because in these types of cultivation the plants eat directly from the nutrient solution and the substrate does not buffer as it happens with crops. to the ground.



📲 Why is the PH of the water going down?


There are times when we fill a tank with irrigation water, adjust the PH and after a while we check again and it went down . Why does this happen? It can occur for several reasons, the first is due to products such as fertilizers, but it can also pass naturally, due to the CO2 contained in the environment.

Some of the CO2 contained in the air is absorbed by the water, and mixed it can be converted into carbonic acid, which can gradually lower the total PH of that water. That’s why we always recommend checking the pH of the nutrient solution just before watering.



🚀 What if we had the opposite problem? How to increase the PH of the soil or water?


It is easier and cheaper to raise the PH of the irrigation water or the soil where our plants are located. Most of the products used to fertilize cannabis tend to raise the PH, and normally tap water comes out with a PH that is too alkaline, so adding a certain amount raises the PH of the nutrient solution, and in turn watering it also raises the PH of the substrate or soilra.

Infographic summarising how to lower or raise the pH of irrigation water.
Infographic summarising how to lower or raise the pH of irrigation water.



✨ Conclusion


Lowering the pH of the water is a basic but very important action, which, as we have seen today, does not cost much to do, neither for time nor for money, and we can also do it with the various products we have at home. Remember that if plants do not have irrigation pH or the correct substrate they will not be able to assimilate the nutrients we give them.



⭐ Frequently Asked Questions


Does salfuman increase or decrease the PH?

Salfuman is hydrochloric acid, therefore it lowers the PH of the water where it is applied, in fact it is one of the most used products to lower the PH in swimming pools. However, it is not recommended to use salfuman in marijuana crops, phosphoric or nitric acid is preferred.


Does bleach raise or lower the PH?

Bleach has a PH that can vary between 10 and 15, which is very alkaline, so the PH goes up. It normally contains a small concentration of chlorine, between 2.5% and 5%, so lowering the PH of irrigation water for growing cannabis plants is not highly recommended.


What is the best solution to lower the PH of the water?

If we had to choose only one product to lower the PH of the water to irrigate the marijuana, it would be phosphoric acid in flowering and nitric acid during the growth phase, even if one of the 2 will be valid for the entire cycle.

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Fran Quesada Moya
Fran Quesada Moya

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