Do you think I have Mustard Algae

Deb04

LifeTime Supporter
Jul 12, 2008
651
Seacoast, NH
Pool Size
19000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Pool was opened a week ago. Was a blue cloudy mess and I have been slamming since then. Now the water looks perfect, but I've been brushing several times a day and I'm still getting those algae puffs, dead algae along the seams, and even an occasional spot where I can see it.

What is making me wonder about mustard algae is that I read in a different post that it doesn't always cause CC. There's clearly some algae, but why so little CC?

These are my numbers.

FC 17
CC 0.5
pH (before Slamming started) 7.6
TA 70
CH 260
CYA 40 (based on addition of 6 lbs over last week. Tested when open and it was definitely < 20. Assumed it was zero as I've lost all my CYA every winter prior.)
Salt 1800, but SWG is off.

Another question: According to pool calculator, the 6 lbs of stabilizer would reduce by pH by 0.7. I obviously can't test it right now with the FC so high, but that would mean it would be around 6.9 right now. Should I add any Soda Ash or deal with that when i'm done slamming?

Thanks.
 
Once most of the algae is dead there is very little CC. Even with a lot of algae, CC sometimes doesn't climb above 1.0. Keep at the SLAM and brushing. Have you performed and OCLT yet? Need patience at this point to see it through and get all the algae filtered out.

You should have lowered the pH to 7.2 before starting the SLAM as it says in the instructions. At this point, you cannot adjust the pH so wait until the SLAM is complete. You can't assume the pH is at 6.9 and adjust now. Just wait til you're done and worry about the pH then.
 
ok. Thanks. Yeah, I admit, I didn't refresh my memory on SLAMming before I started. :(

I have not done a OCLT test yet as I know the algae isn't all dead yet.
 
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