Algae - need a primer!

[heymom1]

Please help me figure this out. We have a 29K plaster inground pool. We've been getting a lot of rain lately and the chlorine feeder wasn't high enough, nor were we running the pump long enough. Anyway, we seem to have some algae growing on the sides of the deep end, in large patches. It's sort of yellowish-tan. Hubby was saying there were stains but I didn't see anything obvious until today, since I don't swim until early evening.

What do I do next? Please give me the whole plan for eliminating this stuff as cheaply and easily (I know, ha!) as I can.

1. How much bleach do I need and when do I add it?
2. Do I need any other chemicals besides household bleach?
3. I am going to have someone else clean my filter, after we do the shock treatment. I thought backwashing and cleaning were the same thing but I was wrong - should I backwash it before the cleaning or is that wasted effort?
4. We're going on vacation in a week, for 10 days. How can I keep the pool from turning while we're gone?

Thanks a ton - I can attach photos if you'd like. Hubby says the stuff is slimy, if that helps. The water itself is still clear, but the stains are visible.

[doggie]

Do you have any accurate test result numbers that we can advise accordingly?

Having accurate test kits are the first thing you should have.

[KurtV]

You need to post your pool chemistry numbers for anyone to advise you on getting rid of the algae. Include free chlorine, combined chlorine, cyanuric acid (CYA), calcium hardness, pH, and total alkalinity. CYA is particularly important.

It sounds like you have mustard algae which can be pretty tough to get rid of. The treatment is simple. Raise your chlorine to shock level, test the chlorine 3 times a day, and return it to shock level after each test. Repeat this until the free chlorine level holds overnight and the visible algae is gone. Your shock level is a function of your CYA level (see here).

You can get rid of this algae and keep it away, but it will take diligence and patience.

[heymom1]

Thank you very much. My son was supposed to have been testing the water but I think we let the levels get away from us this week, what with the rain, the heat, and more sunlight. It wasn't as bad as it is today, and I basically never noticed, and thought hubby was seeing things when he told me there were some new stains.

I will get the water tested tomorrow at the pool supply store, and have son do it with our kit too. Hubby wanted to buy some shock tonight, so we did. I resisted the salesman's pitch for algaecide, though. Do I need the algaecide if I'm already shocking? That stuff is EXPENSIVE!!! We did buy a wire brush and hubby is out there brushing the walls and floor right now. Is that OK & a good thing to do?

Why is CYA level so important? I know you are not supposed to get that number ultra-high, or you have to drain off water to get rid of it.

Do you think I will be able to get this at least under control and then be able to leave it for a week?

[heymom1]

Son just told me that CYA level is 100. I"m going to do the test myself to see what is going on. Now, bear in mind we have just added 1.5 lbs. of Zappit. (I know, but hubby wanted to do something right away, and I didn't have enough confidence in the strictly bleach method until I get the info. from you guys.)

Thanks.

Also: What does "Vacuum to waste" mean? We have no vacuum mechanism, only a Polaris. I can run the Polaris with a fine mesh bag, but I don't know if that will actually clean out the algae.

[heymom1]

One more question - We have an ozonator (electric) on this pool. Please advise if that makes a difference in the treatment from here on out. I think it's still working...NOPE! Its little blue light is out. Now what???

[KurtV]

With a CYA level of 100, your shock level is 25 ppm. Shock as I described in my first post until the chlorine stays at the same level overnight. To clear this quickly, it's very important to test often (at least 3 times a day) and keep bringing the pool to shock level after each test.

Keep brushing; the more the better. If you don't have a manual vacuum, the Polaris may help some.