Cyanuric Acid

[Sue225]

After lots of rain and vacuuming to waste then refilling, my CYA is down to 50!!
Last night I vacuumed to waste and cleaned the bottom of the pool, backwashed, then shut the pump off. This AM the pool was crystal clear with nothing at the bottom of pool. After 2 hours of filtering this AM I noticed the brown stuff gathering again. So, I am thinking that the problem is the filter. I am going to add DE this PM or, do you think I should flock?
You people are the best! I don't think in all the years I have owned a pool, my pool has been better balanced and beautiful! Thanks again

[aylad]

You can always add a little DE if you want--just enough to make the pressure rise by 1 ppm--and it may help filter out smaller stuff. Don't forget that the pressure rise takes a few minutes though, so add it slowly.

I don't think adding floc is going to help--it is designed to make smaller particles that won't settle to the bottom stick together so it will settle. Sounds like yours is settling fine, so there's no need for the floc.

Good job getting the CYA down to 50--now just maintain your chlorine in the 3-6 ppm range. Actually, I would keep it on the upper end of that, but it should be easier to maintain your pool now.

Janet

[CarlD]

You can always add a little DE if you want--just enough to make the pressure rise by 1 ppm--and it may help filter out smaller stuff. ...

Janet

Janet means 1 psi, not 1 ppm. (Pound/square inch, not parts per million).

[aylad]

oops, yeah--thanks for catching that for me!!

Janet

[Watermom]

Her brain is probably just tired having to cover PF so much while I am traveling and not around to help as much as usual!

[Sue225]

I added about 1 cup of de to sand filter and it appears to have blown into the pool. Is this normal? Also, the pressure never went up. Should I add more DE?

[aylad]

It is not normal for the DE to blow into the pool. Did you add it slowly through the skimmer? It should have gone in and coated the sand but not gone through it. How long has it been since you backwashed the filter? Sounds like maybe the sand in your filter is "channeling"--that sometimes happens with very old sand or with a pump that is too big for the filter, where it creates channels in the sand. That might explain why it's not filtering the "brown stuff" out to begin with. Have you checked to see if the "brown stuff" is gritty, maybe it's sand blowing back into the pool?

If you haven't backwashed lately, go ahead and backwash well, then rinse well, then put it back to filter and try a little more DE. I think I'd start with about 1/3-1/2 cup, though, just in case it blows through. If it blows through this time after backwashing, then you've got filter issues that need to be resolved.

Janet