Pool Won't Hold Chlorine

[kirstenbabel]

Recently took over the care of a 25k gallon in ground fiberglass pool. Pool was maintained over the last year using pucks. Pool has a slight green film on all of the walls.
FC 0
CYA 77
PH 7.6
ALK 280
I scrubbed the walls and added 3 gallons of liquid chlorine. By the next morning, FC was 0. Added 1 gallon a day for 4 days, following day FC always 0. Today I added 8 gallons of liquid chlorine at 6pm. By 8 pm FC was 10. By 9pm FC is 7.5.
Why won't it hold chlorine?

 

[mgtfp]

Hey, welcome to TFP!

Likely algae that's consuming chlorine faster than you are adding it.

You seem to have a Waterguru which won't be enough to get you through the SLAM Process, that's required to get rid of that algae.

You need a good test kit, I'd recommend the TF Pro: Test Kits Compared

Once you have that, run a full set of tests and post the results here, and then do an Overnight Chlorine Loss Test to give us a baseline.

In the meantime, add 5ppm worth of chlorine each day to contain the situation.

PoolMath will help you to calculate how much liquid chlorine that is.

 

[Texas Splash]

Welcome to TFP! Along with the solid advice provided above, be sure to bookmark our Pool Care Basics where you will find answers to many of your pool-related questions. Once you are able to post some accurate water test results from a TF-Series test kit, we can easily coach you through the water balancing process and get that water healthy again.