zero TA acid bath

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When raising PH from very very low values it is generally best to use borax, however you can use soda ash if you need to. Either way the TA is likely to come out a little higher than we recommend. Measure TA after the PH is where you want it to be and adjust if needed.

TDS is not an interesting number. It is best to completely ignore TDS, and concentrate on the numbers that matter, like the CH and CYA levels.

Very low PH will cause calcium to be etched off of plaster surfaces and go into the water, raising the CH level in the water. You need to be careful when doing a no drain acid wash to be sure CH doesn't end up too high, or you can have calcium scaling when you raise the PH/TA back up. In situations where you need to remove a lot of calcium, you may need to do water replacement to get CH levels down before raising PH all the way back up, but do raise PH at least part way to stop the acid wash before replacing water.
 
Thanks Jason for your rapit responce.ijust want to give you some values and more info . Ilive in SA and we realy have harch weather in the Freestate , hard to keep pool clean with the dust storms.my pool was build by myself some 22 years ago and just after the marblelite was put on we had a bad dust storm so the appearance from start wasn't good .over the years their war a heavy buildup of calcium and debre stains .the pool is 60 -65 KL before the acid bath the TA was 180 and th PH 7.2 it took. 60 litre acid 33% to lower to 0 or a bit below TA .how many water must I replace and to what ph and ta must I adjust before letting water out .
 
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