I have a 35K gal inground pool, gunite, circa 1971. Pretty rough shape; some leaks in plumbing below the sidewalk, rough walls, some prior layers of paint showing through.
Been running this pool for about 12 years, usually fairly successfully, using 3" tabs in auto chlorinator. Most years, it's worked really well; in a good year the pool stays usable with minimal weekly work (fill chlorinator, dump in soda ash and a small "preventative" dose of algaecide, auto cleaner often, very occasional brushing).
I do ROUTINELY have a problem getting pH UP; it continually goes down rather rapidly. Reasons:
a) Acidic 3" tabs...about 10/week.
b) Presumably acidic rainfall
c) I mentioned leaks; up to about 2"/week replace with acid well water.
Still, for YEARS, I dumped in about 3-4 cups of soda ash/week and moved on.
NOT SO EASY THIS YEAR.
Algae, along with a pink algaelike bacterial infection, have taken hold and WILL NOT give up.
And I absolutely cannot get PH up above about 7.2. If TA is above about 150, soda ash will not dissolve; it just eventually, slowy, gets filtered out. Water is cloudy for days. If I've added muriatic acid recently (tried more than once!!), then soda ash dissoves readily....until TA goes up again.
History this year:
Pool store ID'd excessive (about 170) TA, had me do acid slug & try to recover. No real progress...surprise.
ID'd "high" phosphates (500); added PhosFree to clear.
In attempts to deal with high TA/constant low PH, I've discontinued using 3" pucks and been using calcium hypochlorite.
Even recently dumped 1/3 of the pool and refilled; after that AND 2gal muriatic acid, got TA down to about 90. But of course pH was way low, and by the time I got it up, TA was back up to 160.....
Elevated chlorine to something astronomical for a few days, and scrubbed the daylights out of the walls; pink and green stuff SEEMED at bay. Until this a.m., first time free chlorine dipped below about 5.0. IT'S BAAAACK.....
Found this site a few days ago, started playing with attempts to aerate. Couldn't successfully use existing outlets & PVC (ancient, nonstandard threads in the outlets; I've never found outlet jets to replace the long-gone originals.) Set up a submersible pump (normally used in winter on my pool cover) and a hose nozzle - spray going about 25' across the pool. That should aerate if anything short of a compressor will...I'll see in the next day or two.
a) FC down to about 2.0 this a.m.; added 3 cups Calcium Hypochlorite at 7am. This evening at 6pm, FC was about 9.5 per a newly acquired Taylor test aimed at high/low range chlorine testing. (Yes, I'm considering the kit sold thru this site...)
b) pH, after 8 hrs. aeration, is up to about 7.5 for the first time this year. Was shooting for 7.8--8.0 to try the "yellow out" sold by the store.
c) TA about 160
d) Cyanuric acid about 60.
e) Don't have a recent test on calcium hardness, but the well water is extremely soft and usually this runs low if anything. Was 180 ppm early this year per pool store test.
1) How do I get pH UP and TA DOWN in this pool??
2) Should I be thinking borax? I do have a dog that swims/tends to drink from the pool. But she's about 75 pounds, and USUALLY bites more than drinks.
3) CYA is at 60. AFTER dumping 1/3 water. I'm thinking this is why algae got out of hand, as this site suggests astronomical levels of chlorine are needed at that level of CYA?
4) At 11.5% of CYA, that suggests an ideal FC level of about 7. Resources I have say don't swim above 5. Comments?? How high is too high to swim?
5) Any other suggestions, short of a LONG LINE of dump trucks to fill this thing in???