Test results on new pool in Tucson

[Watermom]

Carl may have not read the entire thread. Shock level is what you want. Even though there is no algae, you have huge chlorine demand. So, you do want to shock the pool and keep it at shock level until you get past it. Sorry for the seemingly conflicting advice.

[CarlD]

Carl may have not read the entire thread. Shock level is what you want. Even though there is no algae, you have huge chlorine demand. So, you do want to shock the pool and keep it at shock level until you get past it. Sorry for the seemingly conflicting advice.

That would be true....oops. But if you're losing 10ppm overnight, it may well be some other contamination you have to metabolize. Algae is, in an of itself, harmless. But it "bleeds" the chlorine out of your water so it can't metabolize the really bad stuff, like animal, avian and human fecal matter, and other bacterial contamination. Algae's just the most obvious and visible.

[Wilco]

I know, I don't get why the drop overnight. No visible issues with contaminants. Bather load is light. Pump is running relatively low pressure, but I guess I can do aa backwash. I still think it's somehow related to the extreme hardness of the water here. I have scaling all around the pool. Takes a toll on dishwashers, water heaters, shower doors in a major way here.

[Watermom]

It may be that some of your CYA biodegraded. That is pretty common and we see it a lot of times in the spring when people open their pools. If it biodegrades, it can leave ammonia as a byproduct which causes a huge chlorine demand to get rid of it. I have a feeling that is what is going on in your pool. Or, you may have some other type of organic in the water that you cannot see that is causing the demand. Sometimes a pool can be on the verge of an algae bloom without having any visible signs and you go through a lot of chlorine. I highly doubt that having hard water would have any effect on chlorine use.

[CarlD]

I don't know of anyone here who has heard of a connection between hard water and chlorine neutralization.
Other than organic matter that the chlorine metabolizes, the only chlorine neutralizers I know of are solar UV rays and Sodium Thiosulfate (R-0007 in the Taylor reagent chemicals).

[Wilco]

Last night, tested at 6 pm, got 13 ppm, added 2 gallons. Got a little rain last night, retest at 7 am, 12 ppm. Added my last gallon. Back to store for more. That's 11 gallons in 3 days.

[Wilco]

Ok, new twist. Given your thoughts that there is still something organic going on. I reconsidered something. At different degrees, there has rather consistently been a loose, brown, fine debris that accumulates on the step down shallow area surrounding the pool, and somewhat in the corners.i thought this was dirt, as we have planters, etc around the pool that may leak into the pool during storms I suppose. I had been brushing daily last month, but had gotten away from that as the chlorine upkeep became paramount. Is this algae/dead algae?