How to adjust alkalinity for the effect of cyanuric acid

Before adjusting pH or sanitizer in your pool, you need to adjust the total alkalinity to carbonate alkalinity. Sanitizers like Dichlor and Trichlor release cyanuric acid (CA) which is a weak buffer. Cyanuric acid may also be added directly as a stabilizer. Total alkalinity needs to be adjusted for cyanuric acid so that you can calculate the correct amount of the chemicals needed to adjust carbonate alkalinity to the ideal amounts.

To determine the carbonate alkalinity the first thing to do is measure the pH, the total alkalinity (TA) and the cyanuric acid concentration. If CA is greater than 90 ppm, dilute the pool water with regular (untreated) water before correction factor found in the following table to get the carbonate alkalinity using the formula: TA – (CA x correction factor) = carbonate alkalinity.

For a pH = 7.2, TA = 120 and CA = 100, use the formula to get 93 ppm of carbonate alkalinity:
120 – (100 x 0.27) = 120 – 27 = 93 ppm carbonate alkalinity

Now adjust your other pool readings (pH and sanitizer) for a safe and balanced pool.

Table for Cyanuric Acid Correction Factor:
pH factor
7.0 0.23
7.2 0.27
7.4 0.31
7.6 0.33
7.8 0.35
8.0 0.36

Cartridge filters, spa filters, pool filters


Filters are used to remove insoluble matter from your pool or spa. Cartridge filters are one of the types of filters used. Over time the accumulation of dirt on the filter cartridge results in the slow-down of the turnover rate making it unacceptable for keeping the pool water safe. The cartridge can be removed and cleaned to remove most of the dirt. Over a period of time the little bit of dirt not removed with each cleaning clogs the pores of the filter and the cartridge needs to be replaced.
If you have not replaced your cartridges in your pool in the past year or in your spa in the past 3-6 months, you should get yourself some new cartridges. Use the numbers from the old cartridge or measure the size of the old cartridge to find the one you need.


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