Mustard Algae, 2nd year of battle

[motomom]

Ok. So for tonight, I'm adding the last two bottles (1.5 gal) bleach that I have, which according to how my pool has reacted in the past should raise my FC level to just over 30. I am also going to add 2 lbs of the Dupont Multifunctional Shock (Sodium dicloro-s-triazinetrione) that I have, just to make sure my FC for the night remains high, and I figure my CYA could be a wee bit higher. Borate treatment will have to wait till next week. Son's future in-laws are coming Sunday (!) to discuss wedding, and they'll be seeing our house for the first time. Bleah. I'm already starting to hate this.

[aylad]

So far I'm seeing you post chlorine results from each night, but none from first thing in the morning so that you can tell how much chlorine you're actually losing to the algae. Some of the chlorine you're losing when testing at night only is being lost to the sun during the daytime, but the way to tell just how much the algae is consuming would be to test at night and again first thing in the morning, and then compare the two.

Janet

[chem geek]

For yellow/mustard algae, it likes to grow in shady areas so check under any removable ladders (if the pool were a plaster pool, then I'd have you check behind light niches, but I assume with your vinyl pool that you don't have those). If you don't kill it at its source, it'll come back unless you keep the chlorine at a higher level (around 15% of the CYA level for maintenance; shock level is 60% of the CYA level) which can be impractical as it is more costly.

[motomom]

chem geek, I do have a pool light, but it has never worked since we bought the house. Well, I'm assuming it doesn't work, since I can't figure out how to turn it on. No switch that I can find seems to work it. So, I probably do need to clean behind it.

Mustard algae is back. I still have not done the borax thing, but hope to be able to do it this week.