Algae Problem with Cloudy Water

[bmlocal175]

Well even though I only lost .5 overnight it is algae.

My wife took a sample to school and looked at it under the microscope. Last week I did notice my FC was 2.5 so maybe it came back sometime then. I still have been adjusting the SWCG to get it where it was and must have had the purifier to low.

So it looks like a shock is in my future in the next couple days, whenever I get a chance.

[PoolDoc]

So it looks like a shock is in my future in the next couple days, whenever I get a chance.

Tonight would be a VERY good time to "get a chance". You can be sure that otherwise, the algae will be "taking their chance"! If it 'blooms' it will me much harder (by multiples, not %) to clean up.

For a ~22,000 gallon pool, 6 gallons of PLAIN 6% bleach added in the evening would be a good dose . . .

[bmlocal175]

I'm still seeing small amounts of algae or mustard algae on the bottom in some spots. I have kept the FC at or above 15 for 2 days and not losing more than .5 to 1 a night. How can I still see some algae? All other readings are normal and CYA around 40-50. pH is a little high, I'm assuming from the high FC. I've brushed and vacuumed almost everyday. Water looks good and is clear. Today I thought, that after I vacuum I pull the hose out and it sits there filled with water. Next day or two I vacuum with all the water still in the hose. Emptied it today after I vacuumed. Could this be the problem?

[PoolDoc]

We've seen several cases of VERY chlorine resistant algae in the last month. There are X options:

1. Hold chlorine levels at 25 - 30 ppm for several days. (No side effects, except increased chlorine use.)
2. Raise borates to 60 ppm. (All side effects are positive; semi-permanent additive. Reduces algae; does not eliminate it.)
3. Use sodium bromide (May not be effective; can increase chlorine use for weeks after.)
4. Use ammonium sulfate or chloride to make monochloramine. (Makes pool unusable for several days; may result in algae rebound after a couple of weeks.)
5. Use polyquat, after allowing chlorine to drop below 10 ppm. (Slightly increased chlorine consumption; improved water clarity; may not be effective.)

Please note that the ONLY choice that I know from my own experience will rapidly kill mustard algae is #4, monochloramine. But, I do NOT recommend it -- it makes a mess of your pool, and in my experience, pools on which I used it seemed MORE likely to have algae problems later.

What I'd recommend is borates. 60 ppm of borates are a good winterizing prep, and will still be there next spring, minus whatever water you drain. Using borates makes the pool MORE, not less, pleasant for swimming. But it's up to you: you can simply raise the chlorine level till the mustard algae dies.

REGARDLESS of your approach, you need to brush, except with the monochloramine option (#4 - Yellow Out, Green to Clean, Mustard Master, etc.)

If you want to go with the borax option, I'd suggest ordering this:
Granular Boric Acid, 55 lb @ Amazon => $117 (2.13/lb)[/INDENT]and this
Lamote Borate test strips

Because the boric acid will lower the pH, you'll need to add borax to compensate; both will increase your borate level. More info here: http://www.poolforum.com/pf2/showthread.php?18597