Hi. I'm using a tablet-based comparator test kit, on a 13,500 US gall pool. My inital tests read FC 5, pH 8.2, CH 220, TA 100, CYA 90. I'm trying to get the pH and CYA into line.
I've dumped (and replaced) 12,500 litres of water and the CYA has fallen to around 75, so I'm on my way with that. But I can't get the pH to budge. I've tested my mains water (which is actually spring-fed) and the pH is 7.2 which I would expect. I've also added three doses of Sodium Bisulphate in 21 oz, 18oz and 18 oz amounts. Still the pH reading is 8.2.
My modest test kit only reads pH up to 8.2. Could it be that the pH was and is significantly higher and will need more PH- to get it down? How high can pH be, is a pH of over 9 possible in a pool? We haven't swum in the pool this year - still getting frosts - but we have never noticed any discomfort in previous years.
I notice from the Pool Calculator that 72 oz of PH- is required to lower pH from 9.2 to 8.2, so maybe I need to keep plugging on. I am worried because the pool store tested my pH at 7.8, but looking at the grubby state of their test kit I'm rather inclined to trust my tests more.
I've added four litres of 5% bleach, by the way. I'm coming off tri-chlor tabs. My FC hardly ever shifts either, but that's another story. And muriatic acid is unknown in the UK. Water is cloudy.