Algae and Diamondbrite

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.

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

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.

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.

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.