Having difficulty reading PH test / PH is not stable

[vanduse1]

I am having trouble keeping my PH in check. I find it very difficult to read the color chart and match my PH. It seems to me that it is always on the high side. It doesn't match an exact color but it may be off the chart. I keep adding Muratic acid. I will be honest that it has been spuratic because of my travel schedule.

I have a 15000 gallon gunite/plaster pool. I just added a pint and a half and will evaluate again tomorrow. My current numbers are.

SWG pool

FC 2.0
CC 0.0
ALK 95
CAL 300
CYA 40
PH ???? Maybe 7.8 but difficult to read...

Is there an easier test to measure PH? Perhaps one that doesn't use color matching? BTW, I am using Ben's new kit.

Thanks! I'm looking forward to everyones great info.

[waterbear]

Phenol red (the indicator in Ben's kit) is the easiest way and one of the most accurate to read pH. If it looks red your pH is on the high side. You want it to be orange. If it gets yellow it is too low and if it is purplish either your pH is very high or your chlorine levels are too high and interfereing with the pH test. If you put in acid and rechecked the pH the next day and it is still high the fix for that is very simple....add more acid and retest. Sometimes it can take what seems like a LOT of acid to ajust the pH. Gunite pools can consume a lot of acid keeping the pH in line, expecially when new. Don't expect to add acid once and always have perfect pH after that. You will probably always have to add acid to a gunite pool.

You also have a SWG! This is probably the main reason your pH is always on the high side. You are generating sodium hydroxide (lye) along with the chlorine!. You need to add acid on a regular basis with a SWG! Each pool is different as to how much acid they may need but you have a gunite pool with a SWG so you probably need to put acid in at least weekly to keep your pH in line.

Adding it once in a while is not going to work and you pH may very well be 'off the chart" at the present time!

My advice is to keep adding acid and checking the pH daily until you get it down to around 7.4, then monitor the pH daily and when it rises add more acid to get it back to 7.4 . You will soon learn how much acid and how often it is needed for your pool and that will make your maintenance much easier!