Algae and Diamondbrite

[DB_BOB]

I have a 26,100 gallon Diamondbrite inground pool that has recently developed problems with green algae. The test results from a pool store are as follows:

FC 1 ppm
TC 1 ppm
CC 0
pH 7.4
Hardness 150 ppm
Alkalinity 80ppm
CYA 100 ppm

With this level of CYA I am going to shock with bleach to get FC to 25 ppm. How long do I need to hold the FC at this level? How much bleach should I add? I'm concerned that adding a lot of bleach will damage the Diamondbrite finish.

This is a new pool that was just filled in March and I am frustrated with the algae (I cannot hold chlorine levels steady), at the same time I do not want to harm the Diamondbrite finish. I live in Houston, Texas with the hot Texas sun.

Any guidance would be appreciated.

[JohnT]

With that CYA, you can't let your chlorine get below 8ppm. Search for one of mwsmith2's posts and download his bleachcalc program if you have a PC. Otherwise, you can estimate that one gallon of bleach will add approximately its percentage concentration in ppm to 10,000 gallons of water. In English, 1 gallon of standard 5.25% bleach will raise 10,000 gallons of water by 5.25ppm

[GraceByDesign]

10.4 gallons of 6% bleach will get you there. (or 11.9 gallons of 5.25%)

You need to keep your shock level up until the algae is dead and you have 0 cc.

[Watermom]

Also, run your pump 24/7 while fighting algae and brush your pool each day. How did your cya gets so high? I suspect you have been using trichlor pucks. If that is the case - no more of them! Just use bleach. You can either do a partial drain to lower your cya to 30-50 or else keep the cya at 100 and just run higher than normal chlorine levels. See the "best guess" table in the sticky at the top of the chlorine forum.

[Simmons99]

Bleach won't hurt your finish - low PH will. Chlorine will kill your algae. Test 3X a day and bring your chlorine above 25ppm - if you let it yo-yo the algae will grow while the chlorine level is low.

AFTER you have the pool BLUE & CLEAR - then you can let your chlorine level drop to 8ppm-15ppm.