Brown gunk on the bottom of pool

[BigDave]

Since pH is stable, I wouldn't move the TA. I would, however, move the pH up a little with Borax, 7.2 is as low as you want to go leaving little room for it to drop. We've had alot of rain recently and my pH went from the high side of 7.4 to under 7.2 in one storm ( my TA dropped as well ). The rain consumed my margin and I was still in the safe zone - had I started at 7.2... You do have room with your TA so if you want to use Soda Ash ('cause you already have it?) then, sure, just do it a little at a time ( 1/4 cup to start ) - let it mix throughly and measure the result.

The Brown Stuff: Does it really bother you? Is it staining your pool?
If it is metals, you might get more when you raise the pH - watch for that. Is there more when the FC is higher?
Perhaps your observation in the CH test is good reason to have your water tested for metals.

[rox29160]

Thanks for the reply BigDave. I will pick up some Borax. I've been waiting all summer for my PH to go up like the pool store lady told me it would, instead of buying something else. I knew I was on the low side. We have had a lot of rain as well, which may be the reason my TA dropped from 90 to 80 and also the reason my PH has not been increasing. I do not already have Soda Ash so it doesn't matter to me which one. I just thought my TA needed to be bumped up slightly too and Soda Ash would do both. I'll stick with Borax per your recommendation.

The brown stuff is just a nuisance. It comes back every day after vacuuming. The water is clear but the brown stuff settles out to the bottom and makes my pool look dirty. Before anybody comes over, I have to hurry and go vaccum the pool.

[BigDave]

I supppose it's personal preference for me. I increase TA with Baking Soda and increase pH with Borax; seems to me it's more targeted - just my thinking, either way will work. BTW, it will take twice as much (by weight) Borax as Washing Soda to have the same effect on pH.
Swamp Mistress ( http://www.poolforum.com/pf2/showthr...-it-all!/page6 ) seems to have had luck with a series of improvised filters.