The Great Tetraborate Experiment!

If you are draining water when it rains then the borate levels will go down, along with the rest of your water balance going 'off'. If you just let the water evaporate then the levels will go back to where they need to be. If your pool is overflowing from the rain then you will lose not just borates but also other levels in your pool will be off, CYA, Salt, chlorine, TA, CH, all of them! How are you testing your borates. Also realize that they just need to be between 30-50 ppm so if they are not exactly at 50 ppm then I would not worry too much about it. If you had a SWG you would be having exactly the same problem with your salt levels, btw. You would also have the same problem with CYA if you are using an unstabilized chlorine source and adding CYA to your target ppm so I don't really understand why you are having problems maintaining the borates.

17K AG pool
pH = 7.6 (consistent for 6 weeks since adding borax)
TA = 140
BOR = 80 (oops)
CYA = 5 (low on purpose)
using 6% bleach with a peristaltic pump feed to maintain 3-5 ppm CL


Question - my TA is gradually floating upwards (started out at 120, now at 140 - I have a heater, so want to drop it a bit).

Anyway, I'm prepared to lower the TA (and pH) using muriatic acid, but want to know if the strategy for reducing TA is the same as posted elsewhere on this forum - use aeration?

drop the pH to 7 nand aerate. Also, the test strips are hard to read above 30 ppm. Try doing a dilution 1 part pool water and 1 part distilled and testings and see what you get when you multiply the results by 2 then try 1 part pool water to 2 parts of distilled and multiply by three. If the dilutions confirm that your borates are high I wouldn't worry too much about it.