High Alkalinity, medium pH, High Chlorine

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
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Joined: Thu 27 Apr, 2006 12:58

High Alkalinity, medium pH, High Chlorine

Postby njpool » Thu 27 Apr, 2006 13:20

I bought a house last fall with a 20X40 inground vinyl pool. The setup includes a system similar to the Pool Wizard (i.e. competing product) plus an inline chlorine feeder. When I used a test strip in fall (before closing the pool), the results showed a TA of about 250, plus a high pH (>7.8) and a free Cl of 10. In prep for closing, I shut down the Cl feeder to get the Cl lower, plus added pH reducer (both dry acid & muriatic acid). I got the pH down around 7.8, but Cl readings were still near 10, plus TA really didn't go down. Through all this time, water was clear & seemed fine (didn't actually swim since it was too cold).

Fast forward to this month. Pool was opened & besides normal dirt, water was clear. Opened up the Cl feeder to shock pool. Cl readings are around 10, with pH around 7.6-7.8. but TA around 250. Just started adding some muriatic acid using the recommended 'pooling' method.

Just to make sure, I am have switched to using chemicals to test the water, but I am waiting for the chemicals to do their thing first. I also will need to run at high Cl when I replace the silver/copper cartridge, as recommended by the manufacturer.

Question is, am I over-worried about the TA? Should I work to reduce Cl levels as well? It never seemed to come down last fall, even after shutting down & clearing the feeder. Other posts note that TA may not be as big a deal if pH is stable & water is clear. What are acceptable highs for TA & Cl?

BTW, a great resource!!!!

Pool Helper

Total alkalinity problem

Postby Pool Helper » Thu 27 Apr, 2006 14:45

Welcome to the forums.
The values you have given indicate a constant high total alk and a high pH, which is to be expected from the total alk level. Also the chlorine level seems way too high.

The problems as I see them are:
- high TA and pH result in inactive chlorine, making disinfection slow
- high TA and pH can cause scale
- high TA and pH can shorten the lifespan of the minerals in the Pool Wizard, Nature2 and other mineral systems
- a chlorine value of 10ppm is extremely high, wasting chlorine and defeating the purpose of using the Nature2

The possible solutions:
- ignore total alkalinity but keep the pH at 7.0-7.2 (7.4 tops) to offset the effects of the high total alk
- when adding pH reducer use the "pooling" method every time
- turn off the feeder to allow the free chlorine level to drop to 0.5ppm and maintain it below 1.0ppm by keeping the feeder turned way down

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