Quote Originally Posted by Kateyru View Post
1) is there a way/procedure to use fewer drops of R-0871 when repeatedly testing FC at mustard algae shock levels?
If you are using the 10 ml sample, then there's no further improvment. However, you can (with practice) learn to eyeball an OTO tester, so you can use it instead. To do so, you'll need to practice by testing with BOTH the FAS-DPD and an OTO kit at the same time.

2) should I continue to lower TA (by adding acid to lower pH then aerating then repeating)
It's low enough . . . unless you want to do borates, which will make your pool significantly more resistant to algae. Info here:
http://www.poolforum.com/pf2/showthread.php?18597

3) When should I add CYA to raise it? I've added several times this summer and am surprised it is as low as 35 but I triple- checked it today
35 is pretty low -- if you can get a box of PoolBrand dichlor bags at Sams Club, I'd do that. If not, I've posted links below for Amazon. It's very hard to buy un-gooped-up dichlor otherwise. But the big question is, does your pool leak? That, or excessive backwashing, would be the only reason for dropping CYA levels. (You know you should ONLY backwash when your filter pressure increases at least 5 psi over clean pressure, right? Your pressure gauge DOES work, right?)

I emailed you links to your Pool History Chart.

Ben
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+ If you need stabilizer, and have access to a Sams Club, buy their 24 pack of 1# bags of dichlor shock. Each bag will add about 7 ppm of chlorine, and about 6 ppm of stabilizer, per 10K gallons of water. Otherwise, order dichlor from Amazon:
Kem-Tek Dichlor 22 lbs
We do NOT recommend buying dichlor locally, otherwise, at least until you are an EXPERT reader of chemical labels. The chlorinating pool chemicals sold at Walmart, Kmart, Costco, and most other local stores are diluted blends, sometimes with copper and other products with bad side-effects.