Phosphate battle

[waterbear]

Before you add the borax and acid for the algastatic effect of borate at 50 ppm work on getting the TA down a bit. Your high TA is why your pH is always on the high side. Here is the reason (warning, it is geeky chemistry stuff):
High TA means a high level of bicarbonate in the water (bicarbonate is the main thing we are measuring when we measure TA--this part of TA is also called "carbonate hardness" or "carbonate alkalinity" or "kH" in water testing other than pool/spa water testing.)
The higher the bicarbonate the faster carbon dioxide will outgas from the water (because at normal pool pH range we have a buffer system of bicarbonate and carbonic acid in the water and carbonic acid is, for our purposes, carbon dioxide dissolved in water, and the higher the bicarbonate level the higher the carbonic acid level to balance it).
Out gassing of CO2 is the main cause of pH rise in a pool (not counting curing new plaster). I hope I have not confused you with this introduction actual chemistry of what is going on! The main point is that if your TA is high your pH is going to rise fast and toward 8.3 and the cure is to lower the TA to slow the pH rise.

At any rate, before adding the borax and acid work on getting the TA down to about 100-120 ppm if you are planning on continued use of your trichlor feeder or to about 70-90 ppm if you are switching to bleach as your main chlorine source (probably a good idea with CYA at 60 ppm!)

Lowering TA is a process so when you are ready for it let us know and we can walk you through it. In the meantime you can read up on it.

[proximo]

Thanks for the help, waterbear. I assume regular doses of muriatic acid are the best way to do this? I have been adding a pint or two in the morning and evening. Is there any danger of getting the PH too low before we hit the target TA range?

Does the use of trichlor tabs contribute to too high TA levels? If I stop using the chlorine feeder will I just have to add bleach every day?

[aylad]

The use of trichlor tabs doesn't contribute to too high TA levels--it's CYA levels you have to worry about with a feeder. Trichlor tabs also are very acidic, so most folks have to make sure that they don't drive the pH too low, but that doesn't sound like a problem for your pool

Here's the method for lowering TA:
http://www.poolsolutions.com/gd/lowe...p-by-step.html

[waterbear]

Here's the method for lowering TA:
http://www.poolsolutions.com/gd/lowe...p-by-step.html

Lowering TA is a process so when you are ready for it let us know and we can walk you through it. In the meantime you can read up on it.

Great minds think alike!