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Can You Use Aquarium pH Down for Hydroponics? It Depends…

Can You Use Aquarium pH Down for Hydroponics? It Depends…

Not sure if Aquarium pH down is suitable for hydroponics? You’re not the only one. Numerous hydroponic cultivators, regardless of their level of experience, are searching for the solution to this inquiry.

Can you use aquarium pH down for hydroponics? Aquarium pH down can be used for hydroponic growing systems so long as they have the same chemical make-up as the nutrient solution used in said hydroponics system. That said, using aquarium pH down with a different chemical formula may negatively impact the balance of the pH of your system.

Read on below and learn all about using aquarium pH down for hydroponics, when it’s ok when it’s not, and more!

Using Aquarium pH Down for Hydroponics

Aquarium pH down is a buffer created and marketed for maintaining balance in aquariums, but it can also be used for hydroponics. However, it isn’t always suitable for such purposes.

In the following sections, we break down the full answer in greater detail.

Is Aquarium pH Down the Same as Hydroponic pH Down?

Depending on the brand and particular product, aquarium and hydroponic pH down may or may not have the same chemical formula. 

For aquarium pH down, the most common ingredients are citric acid, nitric acid, and phosphoric acid. The main ingredient of hydroponic pH down, on the other hand, is typically phosphoric acid or sodium bisulfate(dry acid).

Check the Formula Before Using

Now that you know the difference between the aquarium and hydroponic pH down buffers, you shouldn’t have a problem finding one that works in your system.

The most important factor is that you must check the formula before purchasing or using an aquarium pH buffer in your hydroponic system.

If the pH down is made with phosphoric acid, you’re most likely good to go. If its main ingredient is nitric or citrus acid, however, it is best to keep searching for a pH down with a phosphoric or dry acid-base.

How To Use Aquarium pH Down for Hydroponics

Using aquarium pH down for a hydroponic growing system is no different than using actual hydroponics pH down:

  1. Read the instructions, as products vary
  2. Mix the pH buffer solution, typically 1 ml for each gallon of water in your reservoir
  3. Pour the solution into your reservoir and wait 20 or 30 minutes
  4. Test the system’s water with a meter or pH test strips
  5. Repeat the process as necessary

Start out with one milliliter per gallon. Wait 15 To 30 minutes, and test your water again. Frequently you will only need 1 to 2 ml of pH Up/Down per gallon of water.

Best Way To Lower pH in Hydroponics

The best way to lower the pH in hydroponics is by using a proper pH down buffer. The product doesn’t necessarily need to be one that is marketed for hydroponics, but it must have a matching chemical formula to that of your current nutrient solution. 

General Hydroponics pH Down Buffering Solution

The General Hydroponics pH Down Buffering Solution is one of the most effective and trusted products for balancing hydroponic systems. The buffer consists of food-grade phosphoric acid-base. 

To add this General Hydroponics pH buffer solution to your system, simply follow the same instructions as listed above (for adding aquarium pH down to hydroponics).

Related Questions:

Can I Use Vinegar To Lower pH in Hydroponics?

Vinegar lowers the pH level of nutrient solutions in hydroponics, though it isn’t stable for long periods of time. Bottom line? It’s a quick fix for lowering pH levels, but not a permanent solution.

Can I Use Hydroponic pH Down in a Fish Tank?

Hydroponic pH down may be used in most fish tanks without causing any harm as the main ingredients in these buffers are as beneficial to fish and aquatic life as they are in hydroponic systems.


Hydroponic pH down and Aquarium pH down are, in many cases, safe to use in both fish tanks and hydroponic reservoirs due to having the same sort of chemical composition. However, not all products are suitable for both purposes, hence you must always check the specific formula before using it in your hydroponic nutrient solution.