CYA in Trichlor?

[jhm]

Thanks! Lots of great advice as usual. I've already got him drinking the BBB kool aid.

[jhm]

So my friend brought in his water for me to test today. CYA was way over 100. His FC was about 4. He claims his water is clear and algae free. Does he need to drain now, or just keep the chlorine at a higher level? Seems way out of wack.

Also, does the CYA evaporate with the water? He lives in a really hot location (almost desert), so there is a fair amount of evaporation.

Thanks!

[CarlD]

Does he also have a '70 Cadillac Fleetwood he claims gets 75 mpg?

Seriously, if he checks his FC multiple times a day and is constantly adjusting, or has and SWG it may be true, but he's clearly pushing his luck.

Sunshine and evaporation don't reduce CYA--dilution does.

[jhm]

That's what I thought. He'd not happy since he has to have the pool water trucked in. He's buying into the BBB approach though, which is a good thing.

So you think if he keeps FC around 8-10 he should be OK until he dilutes it?

[Watermom]

He can run high cl levels to compensate for the high cya (but he'll have to be extremely diligent about keeping the cl level between 8-15 ALL the time) or he can do a partial drain. Either way will work. If it were me, I'd do a partial drain, though.

EDIT -- as soon as I posted, I saw that you had also posted while I was typing. If he doesn't want to drain, it's ok. But, he MUST not let cl drop below 8 ever or he is gonna have big algae problems. Hope this helps.

[docsobeck]

i've had some experience with high CYA before learning the BBB approach. if it were me, i'd do partial drain as well, but water around here is among the cheapest in the midwest, so it wouldn't cost me more than 20 bucks. if i had to have the water trucked in, i would try to ride it out. assuming that the pool gets used a decent amount, the water will slowly go down due to splash out and backwashing. (if he has dogs, the splash out will be significant. obviously i have experience in that area. : )

anyhow, he'll have to keep the FC level pretty high, but on the other hand with all that CYA he won't be losing much to sunlight, so it's not like it will take a TON more chlorine to keep it high. that's the way i would go.