Long time viewer, first time poster...I read this thread a week ago and it solved a three year-old problem with rising PH. My PH is now stable at 7.6 for the first time in 3 years and that's even after several thunderstorms. Thank you!!!!!!
I do have a follow-up question:
Do i need to worry about the long term effects of keeping the alkalinity at 60? I've read about corrosion and etched concrete as a result of low TA but maybe that's only a problem if it gets even lower and the PH drops as a result?
Thanks for the advice!
A little more info about my pool:
3 year old 16,000 gallon IG concrete pool using chlorine sanitizer. I have a good amount of foliage coverage and that keeps the water temp around 88 degrees in the summer which is pretty good for the Houston area. I have one persistent water feature which is the spa drop. I use 2 3-inch tabs per week and shock with cal-hypo around once a week to get FC to around a 5. Before reducing the TA to 60 last week, I kept it in the 80-100 range and my PH consistently rose about .2 to .3 per day. To keep the PH below 8.0, I had to add acid about every three days and then add baking soda to offset the TA drop.
I think the plaster contractor did a sub-standard job because I had some very light mottling after both the initial plaster and a re-plaster (see the second pic). The initial plaster from 2013 became rougher over the course of the first year which is why we had them re-plaster in 2014 (acid-washed / bonded new plaster). That helped with the roughness but the new plaster still showed mottling. They told me the mottling patterns were just natural patterns in all plaster. I'm not so sure.
One other bit of information that's probably unrelated to the PH issue but I'll mention it - I had a recurring problem with yellow algae every summer. Yellow-out or simple super chlorination would make it disappear for a few weeks and we did disinfect everything - pool tools, swim suits, etc., but the algae would always come back even with FC at a 6. The bouncing PH problem just made it worse since it would grow faster as the PH approached 8.0. This was still happening with phosphates at 0 and CYA no higher than 50. Apparently it's a problem for others in the neighborhood including my brother-in-law. About a month ago I caved and used Bio-Dex Aqua Pure which is a combo copper / quat algaecide and I haven't had a problem since. I know the risks, but so far I haven't seen any staining and am thrilled to not be brushing the walls multiple times a week in the summer. I used a copper testing kit and the copper level is about .07 ppm after the initial treatment. I'm pretty sure the PH problem was unconnected to the algae issue because 1) the PH would still rise rapidly in the winter when there was no visible algae and 2) the PH was still rising 2 weeks after adding Bio-Dex and having no visible algae.
PH: 7.6 and stable (finally!!!)
Copper: about .07 ppm
Pool plaster 2014
Mottling still visible while filling the pool after new plaster job