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PH Levels in Water and Why They Matter

pH Levels in WaterBefore starting an Aquaponics system I had barely heard of the term “pH levels” but I very quickly learned that good pH levels in water are important to having a healthy system with fish and plants that are thriving!

PH stands for a chemistry term “power of hydrogen” but that is where it gets a bit too science-y and I’m going to leave it there.  What it is is a measure of the acidity in any fluid.  Lower values (1-6.9) measure acidity where the higher levels (7.1-14) measure alkalinity.  A direct 7 is considered a neutral pH.

The pH levels in the human body are in the low 7s with the ideal blood pH being 7.4.  The levels of pH in the ocean are generally between 7.5 and 8.5.  Orange juice has a much lower pH level of 3.5 where Ammonia has a pH level around 11.5.

In your Aquaponics system, the ideal pH levels will vary slightly depending on the plants you want to grow as well as the fish you are hoping to use.

Fish will tolerate pH levels in water of:

Tilapia 5-10 (preferring between 7-8)

Gold fish 6-8 (with 7.2-7.8 being the best)

Bluegill 6.5-8.5

Trout 6.8-8.4 (they like as close to 7 as possible)

Catfish 6-8

As you can see, most fish prefer their ranges to be as close to neutral as possible or mildly alkaline.

Plants will tolerate pH levels in water of:

Cabbage 6-7.5

Onion 6-7

Strawberries 5-7.5

Cantaloupe 6.5-7.5

Tomato 5.5-7.5

Plants typically like to grow where in areas that are slightly more acidic.

So with fish that prefer slightly more alkaline water and plants that prefer slightly more acidic, the general consensus is that the most ideal water pH levels should be as near to 7 as you can achieve so as to make both the plants and the fish happy!

A word of caution though, the biggest issue is that plants and fish don’t like the water changing from acidity to alkalinity quickly.  If you see dramatic fluctuations in your pH levels then you should be worried.  If you work on gradually bringing your system to a pH level of 7 then your fish and plants should manage just fine.

As long as your tank stays stable within the range of 6-8, you should see growth from both your fish and your plants.

Testing your water simply requires a water test kit.  Check out our review of popular test kits here!


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