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Understanding pH (A Case Study from Lake Master Pros)

I am working with a customer on High pH levels of their lake. This info can help understand how ph works and overall health of pond. In small ponds adding acid to a pond can be a temporary fix. But addressing the underlying problem is the trick and can lead to a solution.


The pH in lake raises concerns. Overall, a plankton bloom will raise pH, sometimes significantly and this is normal. That being said, I still would have liked to see the pH a point lower all over lake than what I was experiencing. The graph below gives a good indication of pH levels over the lake.


Fish growth will be limited during low or high pH levels. Fresh water fish on average have a blood pH level of 7.4. This would be optimal conditions for spawning thru adulthood. Most conditions are not optimal, so acceptable ranges would be 6.5 to 9.0. Overall fish can adjust to their environment and tolerate pH extremes. In a hatchery situation we try to create optimum conditions. We have a more controlled environment. I consulted a couple of Biologist to get an outside opinion over my own. The question is at what point when pH rises do the fish eggs stay viable. As the pH pushes its way up to and past 8.5 spawning and the viability of the eggs gets less and less. Fish growth is limited from 9-11 and fry will die 11 or higher. Also, , pH is highest at dusk and lowest at dawn. This is because nighttime respiration increases carbon dioxide concentrations that interact with water producing an acid and lowering pH. This can limit the ability of fish blood to carry oxygen.


This is a large lake so options are limited and it will not be a quick fix. Alkalinity and Alkaline properties neutralize acids. Borates, phosphates, carbonates are some options that can neutralize acids. Incorporating this would take, planning, time and money to come up with a solution to reduce pH. Altering the biology of a large body of water would be the goal. Simply adding acid to the lake will not change the biology or the underlying problem. It will take other environmental changes to start making headway and reducing the pH.

If the water below has a more preferable pH, he suggested mixing the lake. This would require installing diffused aeration systems in different parts of the lake. Air is used to move bottom layers to the top. He has done this with a lake that was close to 100 acres and was successful in reducing overall pH. We could break this down. This scenario could be applied to a few smaller areas of the lake to help create areas that would be conducive to spawning, creating better conditions. Fish usually find their ways to parts of a lake that are healthier. This option is only viable if the pH is lower at deeper depths.

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