Closing with "pink slime and white water mold"

[PoolDoc]

Chlorine doesn't penetrate slime quickly -- the slime is a protective adaptation of the organisms producing it, and is designed to protect them against environmental threats. Brushing is important, because the slime is usually adherent, not free-floating, and brushing not only knocks it loose, but it disrupts it so chlorine can reach inside more easily.

But the nice thing about treating covered pools off season is that you don't have to be quick -- slow is OK. Just keep the chlorine up high and brush occasionally.

There *is* another option, but I don't usually recommend it. Monochloramine, which can be formed in the pool, by adding BOTH chlorine and ammonia while keeping the pH high, penetrates slime layers much, much better than regular chlorine. But it's tricky: if the pH is not high enough, you get dichloramine or even nitrogen trichloride, which are useless and stinky. And, if you don't get the ratios right, you'll use up both ammonia and chlorine, as you oxidize the ammonia, and end up with nothing in the pool. Even worse, when you're done, monochloramine is very irritating to swimmers, so you have to get rid of it.

But, if you're going to use monochloramine, winter's the time. The process would be:
1. Shock and then brush the pool.
2. Add borax till your pH reaches 8.0
3. Add polyquat to prevent growth, and then let the chlorine drop.
4. Once the chlorine is 1.0 or less, add the ammonia (Yellow Out, Mustard Master, etc.) and a 'booster' dose of borax, to make sure the pH is high. Yellow Out is available on Amazon. Be *careful* -- most of the other "Yellow" products are sodium bromide, which won't help you.
5. Add bleach (instead of cal hypo) per label instructions, using 1 gallon of plain household bleach to replace each pound of cal hypo.
6. Wait 1 - 2 days, then brush.
7. Begin dosing with chlorine to maintain TOTAL chlorine levels above 5 ppm. Combined chlorine (monochloramine is a combined chlorine) levels will drop over time, and free chlorine levels will increase.

But, I'd really, really recommend simply keeping chlorine high for awhile, and brushing occasionally instead.

[CarolineM]

Thanks PoolDoc - I was ready to give up! I'll keep on trying

[PoolDoc]

How did this work out for you?

[CarolineM]

I kept the shock level up until late December. Used $300 worth of clorox! Pulled back the cover in March and vacumed and brushed - didn't see any. Opening tomorrow so we'll see if it shows back up. That's the worse stuff I have ever delt with! Thanks for checking on me, PoolDoc! Sure did appreciate all your help!

[PoolDoc]

I kept the shock level up until late December. Used $300 worth of clorox!

Ouch! But I'm glad it worked out for you. Let us know how it goes this season.