CYA and FC question

[kwickimom]

ok all-

I cannot get my pool to keep cl at all. I added .6 gal to a 7600 gal vinyl pool which if I did the bleachcalc correct should have raised it 5 ppm. My FC got to 3 and then 8 hours later was at 0. I origainally thought my CYA was 30-50, but now (i just have the 5 way test strips from walmart) maybe CYA is at 0 (the colors are sooo close). do you think I should try and raise the CYA a little and see what happens? what to do...

thanks!!

[prh129]

Without stabilizer (CYA) sunlight will break the chlorine down quickly so you should definitely get some CYA right away. Don't forget it takes awhile for CYA to register so wait about 5 days to test.

It is also possible that you have something in the water consuming the chlorine. If you add your chlorine after sundown and re-test in the morning, that should help determine what the culprit is.

I would also suggest you get a drops based kit to get a more accurate reading. Some WalMarts have the HTH 5-way test which includes CYA.

Peter

[aylad]

It is not abnormal for a pool to lose 3 ppm over a day time--but whether it's because your CYA is too low or because you have something in the water using up your chorine is anybody's guess. I would try shocking it for a day or so, then let it drift back down, and see if the consumption stays the same. If it was matter consuming it, then you should be able to see a chlorine residual. If the consumption is the same, then I'd try raising the CYA.

Janet

[brent.roberts]

You really need to get a better test kit. Walmart has one for about $ 15.

This kit will test for free chlorine and total chlorine. When you know both of these numbers you subract free from total and it tells you what you "combined chlorine" level is.

Combined chlorine is chlorine that has been partially used oxodizing stuff in the water. The stuff could be just leaves and debris, or kids pee and fecal matter. The fecal matter is where there dangerous infections come from. This is why you need to know the combined chlorine ( shorthand CC ).

If you discover you have a CC level of 0.5 or more then there is "stuff" in the pool that needs to be oxodized to sanitize the pool. If you keep adding regular doses of chlorine, you will not attack the CC. You need to raise the level of chlorine to shock levels to burn it out.

What the shock level is in your pool will depend on the CYA level ... another reason you need a better test kit. See the article at the very top of this section "best guest CYA" That will give you more info.