In an aquaponics system the biologic reactions are constantly bringing the pH down. I developed this point in other videos and explained how to maintain the pH in the desired range. However, I still receive the question “How can I lower my pH in aquaponics?” frequently so in this article and video I will respond to this point.
Why would you need to lower your aquaponics pH?
I see 2 situations where you can desire to decrease your water pH.
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You have limestone in your system (generally in your media).
If this is the case you made a mistake when you selected your media and didn’t follow the recommendation I give in my videos to test the media with vinegar before using it. In this case I would simply advise to change the media and replace it with an adapted one. This is a lot of work but probably the best solution.
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The water you are using to top up your system has a high pH.
If the water you are using is too hard, you can condition the water before using it.
The 2 ways to decrease your water pH
Reverse Osmosis method
First you can use a reverse osmosis filter. This will push the water through a membrane and will leave you with a water almost pure. Unfortunately this process consumes a lot of water and is therefore not really sustainable. Also you can’t use the water as is, you will have to re-balance the pH by adding carbonates and other minerals.
Phosphoric acid method
I would recommend to stock a large volume of water in a tank with aeration and to add little quantity of phosphoric acid until the pH reach the desired level. I don’t recommend to add the acid directly into the aquaponics system as it could drop too quickly due to the carbonate buffer being neutralized. When you manipulate phosphoric acid it is important to be well equipped with gloves and protective glasses.
A lot of different acids are available but they are not all adapted to aquaponics. The advantage of phosphoric acid is that it increases the phosphorous available for the plants.
Welcome here! If you are new, you will probably be interested to discover Jonathan’s six steps to build and manage an Aquaponics system. Click here to access for free! Thanks and good reading 🙂
