high Chlorine usage

[oldkingcole]

1981 15,500 gal fiberglass in ground (11x32 8ft deep 3.5 ft shallow) with a sand filter.
Location: HOT Arizona Desert
water is crystal clear (I can even see some small stains on deep end floor standing outside shallow end)

Alkalinity 100
cya 30
Total Hardness >1000 test I have only goes up to 1000 (estimated calcium 666)

Don't have a borate tester but I've added 12 boxes of 76oz 20 mule team (as per pool calculator) and acid to drop ph back down to 7.8

My problem : I'm adding a 1.42 gal of 6% liquid chlorine DAILY.

I've been pouring it shallow end in front of return at dusk roughly 7-8pm.
testing before bed 11pm I get 5 ppm (or maybe higher since oto test only shows up to 5)
Morning test 7-8am still at 5 ppm
afternoon testing 2-3 ppm (unless kids have friends over then even lower and I add more bleach to keep from running out of FC)
evening test 7-8pm back down to .5 or less
and I start the cycle all over.

I'm going thru 35-40 bottles of 1.42 gal 6% bleach a month IDK but sure seems like a awful lot ?

I thought 30 cya was ideal should I raise this to ____?

[Watermom]

You'll probably do better with a higher CYA. We typically suggest 40-50 for most pools, but pools in extremely hot sunny locations often do better even higher. One of the moderators, Aylad, lives in NW Louisiana with high temps and full sun and she runs her pool at a CYA level of 70-80ppm I believe. She finds that by doing so, she can add bleach less often and maintain chlorine levels through the hot sunny days. Of course, you do have to run higher than normal chlorine levels (see the Best Guess Chlorine chart in my signature below). Maybe up the CYA to 50 and see how that does for you. If you are still losing chlorine too fast, go to 60. Better to do this gradually than go higher than you want by too quick of a change.

[oldkingcole]

There is very little shade on the pool. From before 9am to past 6pm it's in full sunlight. High air temps right now are in excess of 110 degrees with a drop to 90's at night. Hence why we don't bother having a heater. Wal-mart had HTH 4 lbs jugs of 96% CYA. Pool calc said to go from 30-60 I needed 62oz. So I just went for it and dumped the whole thing. I'm not 100% positive I even had 30 ppm since the test only goes down to 30 it could be even lower? If tests out above 60 ppm tomorrow, I'll just deal with keeping slightly higher chlorine ppm. My question is this: If I lose 90-100% of 5 ppm chlorine at 30 ppm of cya. Raising CYA to 50-60 which equates to maintaining chlorine level of 8-10 ppm and I lose 50% a day (4-5 ppm loss) isn't that the same? 100% of 5ppm lost in 24 hrs vs 50% loss of 10 ppm in 24 hours is still 5 ppm per day

[PoolDoc]

Pool Chlor, a service company that has run 10,000's of pools in Arizona since the 60's, sets up their customer pools with a CYA of 150 ppm, and then runs chlorine levels that approximate the ones in my Best Guess chart.

You don't have to go that high, if you prefer not to do so, but 30 ppm CYA is too low for sunny AZ.

[aylad]

My CYA is currently 90 ppm (intentionally) and I'm currently losing about 3 ppm of chlorine a day in approximately 29K gallon pool. Air temps 104-109, water temp today 97 degrees. There is a very obvious increase in chlorine consumption in my pool when the CYA gets any lower--I have a lot of splashout/replacement due to a high kid/dog bather load, and my chlorine consumption drastically increases when I get below 80 ppm CYA.

[oldkingcole]

I tested the CYA this morning after dumping 4 lbs last night. I could still barely see some black at 60 but not at all at 50, so I think it fell somewhere in between. CHL looks dead on 3ppm (hth oto test). I'll see what kind of drop I get? Told wife & kids to stay out while I try to dial it in.

After adding the cya I noticed a small decrease in PH? Is that normal? I'm assuming CYA PH is lower then the pool water which caused the drop is that accurate?

[oldkingcole]

Janet,
At 90 ppm CYA how high do you keep your CHL? B.G.C. chart says 5 min 10 max 20 shock does that work for you?

Anyone,
Is there a easy formula to figure out exactly how much ppm I'm adding per ___ amount of chlorine to ___ gallon pool

[PoolDoc]

For your pool, each gallon of plain 6% household bleach will add about 4 ppm of chlorine. A pound of 62% available chlorine dichlor will add about 5 ppm. That's pretty simple.

Ben

[aylad]

Janet,
At 90 ppm CYA how high do you keep your CHL? B.G.C. chart says 5 min 10 max 20 shock does that work for you?

I keep mine at 8-9 ppm, at the higher end of the range, and my pool stays crystal clear year round.

Janet

[oldkingcole]

First off THANKS for the replies.

I didn't get to test until 11am (3 ppm) now at 9pm CHL at 1 ppm. That's a lot better then it's been. Before raising the CYA to 55 I've tested in the afternoon and been +=5ppm and by 8pm it's -= .5 ppm. I'm going try 2 gallons tonight (8 ppm added to 1 = 9) and see how long she'll hold 5 or above. If I can hold += 5ppm for 24 hrs I can live with that. Just 1 1/2 to 3 gallons per day is a bit more then I bargained for.