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Why would my CYA levels drop from 27 one week to 9 the next.
I had my water tested at the local pool store and the CYA was 27. I added 2# of Stabilizer to bring it up ran the pump 24/7 for four days. I have been shocking the pool for the last 3 days for an algae problem.
Then when I had the water tested a week later (today) they said my CYA was at 9. Can this be correct? I used a strip test and it confirmed that it was low.
Can someone help me out.
THANKS!
Stabilizer testing is very subjective, and there are a lot of things that could give you different readings. For example, if they're testing via turbidity test, having algae in the pool will usually give a higher than accurate reading. If you're using strips, then shock levels of chlorine can bleach out the test, giving a lower than accurate reading. Depending on how bad your algae problem is, the algae could be degrading the CYA that's in the water, causing the levels to drop.
My advice is to buy a drop-based kit, test it yourself, and dose your pool accordingly. I wouldn't do anything based on strip testing.
Janet
To build on Janet's accurate statement: When you do your drop testing yourself, you try very hard to do it the same way every time. So even if you are "wrong", you are always "wrong" the same way.
GREAT!
Thanks for the replies.
Now where can i buy a good drop-based kit?
If you don't want to drop $50+ on a test kit, Walmart sell (for $15.99) a 5-way drop test kit that should do you fine for now...just get the one that includes the test for CYA....Just re-enforcing Janet and Carl: ANYTHING is better than the test strips !!
Good luck
If you have the WalMart kit and are strapped for $$$, you can get just the Taylor FAS-DPD test kit (just tests Chlorine) for about $25
Thanks for all the help! I just got my kit today. Now, how often do I test the water?
Unless you're using trichlor tabs or dichlor for shock, there's no need to test for CYA more than a couple of times per season, since the only way to reduce it is through splashout/drain and refill. If you add granular CYA, don't bother to test for it for about a week after you add it because it takes a long time to dissolve. If you're using trichlor or dichlor I would test for it at least every two weeks because those products can raise your CYA (and lower your pH) very quickly.
It's not a bad idea to test your water daily for chlorine and pH until you get a feel for how often to add chlorine, whether your pH rises, etc. I would also test for TA every week or two. I still test my pool a couple of times weekly, and this is my 6th year with the pool open year round.
The more frequently you test, the less likely you are to have problems come up that require a LOT more time to correct!
Janet
After getting used to the test methods I have some numbers that I would love for the "experts" to look at.
Ph 7.4
FC 14 Has been that way for a couple days.
CC 0
TA 200-250
CYA 60
The water is crystal clear.
Are these numbers OK?
I seem to have "sand" in the bottom of the pool and "grit" on the sides of the pool. Could this be caused by high TA levels?
THANKS!
Your numbers look perfect to me....what about calcium? It's not necessary in a vinyl pool, but if the level is too high it can precipitate. Chances are the sand in the bottom of the pool is dirt that's blown in, or in my case, pollen that blows in and then sinks. I stir it up and let my filter run, and it does a pretty good job of getting it out.
Janet