Persistent high CC

[Ronald U.]

I need help. I began a green algae SLAM 23 days ago. Back then there were 6 or so hand sized patches of algae on walls, water clear. Since Day 2 SLAM no visible algae, water clear. I am unable to reach SLAM completion due to persistence of CC between 1.0 - 2.5, usually 1.5. Running out of ideas I raised FC to mustard algae SLAM 6:30 pm yesterday. Today's numbers:
FC 22.5
CC 1.5
CYA 30
TA 50
Borate 40

About 10 days ago I added trichlor pucks to feeder to raise CYA from high 20's to mid 30's (using Pool Math). CYA has rapidly drifted back down into high 20's by yesterday's reading. There have been several inches of rain during the SLAM. Pool overflows. Cleaned DE screens 2 days ago. Screens were caked but no green visible. Any suggestions are appreciated.
Previous thread http://www.troublefreepool.com/threa...-can-SLAMs-run. Started this new one as it seemed the old thread was losing steam.
I've never quite understood how to distinguish green algae from mustard algae.

 

[Mr Bruce]

That is usually indicative of algae hiding in a hard to reach spot. Behind niche lights, in ladders, in wedding cake stairs, in skimmers behind weir doors, etc.

 

[Ronald U.]

Scrubbed in light niche, nothing visible. Scrubbed in skimmers, nothing visible. What are wedding cake stairs and how can algae be inside them?

 

[camueller]

Scrubbed in light niche, nothing visible. Scrubbed in skimmers, nothing visible. What are wedding cake stairs and how can algae be inside them?

This kind of thing. They are hollow inside and fill with water when sunk in the pool. Algae can grow inside.

Blue Wave White Wedding Cake Above Ground Pool Step with Liner Pad-NE110WH - The Home Depot

 

[basod]

I see you have a Tiger Shark in your signature if it's been in the pool during these OCLT tests I'd remove and retest - they can get funk in them.
Is their a main drain in the pool? check under the screen for debris if possible.

You could do an OCLT test on your filter water by shutting it down overnight test some water off the drain, and test the pool separately before restarting the pump.

 

[Ronald U.]

I've never messed with main drains. Is there a good how-to you can point me to? As in how to open, inspect, etc. Thanks.

 

[basod]

Mine has a few SS screws dive with a mask remove them and take a look.
the sealing ring to the liner on mine is beneath the cover
being a gunite pool the drains are sealed to the basket underneath