Closing with "pink slime and white water mold"

[CarolineM]

Oh man, what is going on with my pool? When I do the PH test at first it looks ok - 7.6, THEN it turns a PURPLE color - using the phenol red. Tested with the Leslies kit - using R0014 and it does the same thing - at first looks like 7.6 then goes to deep red. Still holding my chlorine at 15ppm, but until now my PH tested normal! Pool is clearing, but now there's a ring in the skimmer - kind of looks like mud. Could that be from dead white water mold??? Had this pool 15 years and have never had these problems! Help!

[PoolDoc]

Perfectly normal result, when you have very high chlorine levels. High levels of chlorine convert "phenol red" to "chlorophenol red", which is a different indicator. Don't worry about it! If you are using nothing but bleach, your pH won't change too much.

What's the texture of the ring in the skimmer? (It could be organic debris, from all the algae & slime . . . including white mold.)

[CarolineM]

Thank you so much PoolDoc! I was SO worried! The ring in skimmer is kind of like mud - I clean it off and it reappears daily. Hopefully just organic debris. Pool is completely clear now, but can still smell the combined chlorine - can't see anything to vacume out - will brush again today and continue to maintain 15ppm. Ordering phosphate kit today - but, won't rain add phosphates?
Thank you PoolDoc and CarlD - don't know what I would've done without your help!!!

[PoolDoc]

Rain can add nitrates (another algae nutrient), but I don't believe it adds phosphates.

That said, I have not fully explored the avenues by which phosphates enter the pool. However, I'm sure the two primary routes are treated fill water (well water wouldn't normally contain phosphates, but 'city' water usually does) and phosphonate based metal / stain control products. A third route are United Chemical's products. Many of those contain phosphates, apparently as a detergent to improve chlorine & bromine penetration of algal biofilms.

The issue with city water is the reason we'll need to test BOTH your pool water AND your fill water.

[CarolineM]

Well, brushed the pool a couple of days ago - it looked so good I almost didn't brush - the water is crystal clear - but there was the stuff again - it looks like clear mucus - just saw a little bit when brushing the deep end. How can it still be there?? I'm beginning to think that Clorox alone is NOT going to kill this stuff!

[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