First time pool owner, bought a house with an 18x36 IG pool, opened it up a couple weeks ago and have been reading here voraciously to try to understand pool chemistry. Sheesh when my dad owned a pool, all we did was dump a couple coffee cans of liquid chlorine in every few days, who knew it could be so complicated!?!
Anyway, I have a question about Cyanuric Acid. It seems (from reading the board) that people are all trying to either add it or get rid of it. I THINK I understand why - not having any means your free chlorine gets eaten like crazy, having too much means you can't get any free chlorine. I seem to have a different problem (or maybe it's not a problem, hence my question).
When I first opened the pool, there was no chlorine. I had shocked a couple times over the winter per the previous owner's suggestion and the water was crystal clear at open, but the numbers were bad. After mucking for awhile I was at FC of 0.04, TC of 0.06, CYA above the meter's ability to read. So I read more and mucked more and I seem to have settled in to the following numbers (it has drifted slightly over the past week or so, but not much):
FC: Above the meter's ability to read (>10ppm). I am testing three ways - I bought a ColorQ 7 Plus because my color matching skills are pretty weak and also with test strips and a standard (simple) drop kit. I'll be ordering one of the TFP test kits tomorrow. All three show FC and TC above range.
TC: Above the meter's ability to read.
pH: 7.4 (pretty steady - 7.5 3 days ago, 7.2 6 days ago)
TA: 151 (this one seems to fluctuate - it as 115 three days ago and 128 three days before that)
CH: 81 (increasing - 75 3 days ago, 69 6 days ago)
CYA: 110 (fluctuating - 91 3 days ago, 115 6 days ago)
I haven't put any chemicals in for the past 6 days.
The water is crystal clear, there is no smell, and there is light sediment on the bottom (I vacuumed the other day, nothing since).
I should also note that the pool has a slow dissolve chlorine tablet thing coming off the filter and I put some tri-chlor sticks in it when I first opened the pool. They are now gone and I haven't put any more in since it seems tri-chlor adds CYA. So I'm using liquid chlorine exclusively, though, again, I haven't put any in in nearly a week.
So my question is: Do I have a problem? I am going to try the "test 1/5 the sample and multiply by 5" trick to get a better idea of the actual FC/TC numbers tomorrow, but should I be concerned? I saw in one post where having 10-11% of CYA means that there is "enough" FC to do the job and I also read that there is no "safe maximum" for FC so having 10 ppm for a CYA of 100 should mean that it is safely protected from bacteria/algae and also safe to swim in. Other than the presumed difficulty of keeping the FC that high (a problem I do not, for some reason, seem to be having) is there anything inherently "bad" with having a 100/10 ratio instead of the more normal 40/4 ratio? I'd sure as heck like to avoid draining 10k gallons of water into my backyard if I don't need to, but obviously I don't want my kids swimming in an unsafe pool.
Any advice/guidance is very welcome. This is a great board and I already ponied up my money to support it