My questions primarily concern the "goals" on PoolMath. I seem to consistently get "balanced" results on the CSI using PoolMath, even though I'm pretty far outside the "goals" it shows for me.
Since I last posted here, I had to drain and refill again, and this time the pool is filled with almost entirely soft water. Today's readings (Taylor except as noted):
FC: 21 (FAS/DPD)
CYA: 33 (this is hard to read -- ColorQ says 31)
Salt: 3000 ppm
CSI: 0.26 balanced
Question 1: How high MUST I get my CYA? The Pool School doesn't even list any figure lower than 60 for CYA in a SWG pool, and PoolMath says it should be 70. Is there any actual harm if my CYA is 32, as long as there is adequate chlorine in the pool? Right now I have excessive FC because I've been both running my SWG and putting leftover CYA tablets, er, I mean trichlor tablets, into my skimmer in order to get my CYA up (I have about 30 lbs of the tablets and I figured WTH, they increased my CYA to ridiculous amounts before I had the SWG so why not). I understand this is a bad idea over the long term, but I don't plan to do this any longer than needed to get the CYA back up. I plan to turn off the SWG today, so the chlorine should return to something more normal.
Question 2 is about my CH. It is actually low; PoolMath says my minimum should be 250. I was measuring 225-250 the last couple of times I tested, which was on the low side but close. Today it really seems to be about 200. Do I need to be concerned, given that the PoolMath says I am balanced? I don't want to eat up my pool, but after the calcium buildup I've had in the past, I do want the calcium to be as low as I can safely go. If I should increase the CH, would it be okay to slowly increase the CH by simply turning off the outside softener for a while and letting the extremely hard tap water do its thing to slowly increase the CH?
Question 3: In another thread here, ChemGeek said: "The CH may continue to go down with water dilution from rains so adding more calcium would be reasonable. I do that over the winter since I'm diluting to reduce salt, but don't want the CH to get too low." I am confused. I thought that CH was like salt, that dilution would only apply if the pool overflowed or at least that the total quantity of water went up. We actually did have some rain here in Vegas in the last few days, although the quantities were pretty minimal as you might expect. Could even a small amount of rain explain why my CH test went from 225-250 down to 200 today?
Question 4: I have noticed that my PH and TA have been verrrry stable since the last refill. I last tested two weeks ago. At that time, I added 22 oz of acid two weeks ago and today's test shows the exact same readings as I had before I added the acid. In fact, they are the same readings I had a week before that. Even before the refill, I noticed that my pool really likes to have a PH of 8.2 and TA around 110-130. PoolMath says my goals should be 7.8 max for the PH and 70 minimum for the TA. I can bring my pool within those goals only with a LOT of acid, but after I do that, they go right back up to the 8.2/130 figures and then stay there. Here's the question: Given that PoolMath says my pool is balanced at 8.2/130, can I just not worry about those readings? Would they hurt someone swimming (not that anyone is swimming now)? Or, would this cause other problems in the pool?
Thanks for your help.