New to forum, black algea problem.

I have been fighting black algea for about a year. I just found this forum and have been putting nothing in but bleach for the past 3 weeks,about 20 gallons, but before that, just about anything the pool store would sell me. My water before was cloudy and green, now crystal clear but I still have traces of black algea. Will it slowly go away now that chlorine levels are up? Or do I need to shock it some more? The black algea treatment from the pool store seemed to work to cut it down, but I am afraid to put in any more crap.

At least on concrete pools, eradicating black algae is very hard, because the algae seems to extend 'roots' down into concrete. You can control it by maintaining high-ish chlorine levels on a consistent basis + brushing regularly.

The Best Guess chart will explain what appropriate levels of chlorine are, and why. Link is in the blue signature box below.

When you say control, do you mean that the black will recede? Is it OK to abandon the BBB for a moment and hit it with some algeacide? This stuff has got to go, I am embarassed by the way it looks.

Algaecide (60% polyquat is all we recommend) is a pretty good preventative but not so much help in killing algae. You need to stick with high chlorine in your fight against black algae.

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Originally Posted by lucas2

Is it OK to abandon the BBB for a moment and hit it with some algeacide? This stuff has got to go, I am embarrassed by the way it looks.

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There's nothing that is compatible with human swimmers that will eradicate black algae within a few days. Available algaecides are ineffective against black algae, and by ineffective, I mean much less effective than chlorine.

VERY high levels of monochloramine (ie, Yellow OUT) would be probably be effective if sustained, especially if combined with a phosphate detergent, like STPP which is included in several companies anti-algae products. But doing so would leave you with a huge chemical mess to clean up. Plus, creating and sustaining high monochloramine levels requires an attention to detail missing from most pool owner's dosing methods.

Not to put too fine a point on it: but your black algae didn't suddenly appear (if it did, it's not black algae) and it's not going to suddenly disappear.

Of course, if you go in a pool store, insisting you want to get rid of black algae RIGHT THE HECK now, you are going to end up a mark for a predatory pool salesman.

If you are really determined to get rid of it completely, and are willing to 'do what it takes', do ALL these things:

1. Go to the test kit page, and order BOTH a K2006 and the LaMotte borates strips ASAP.

2. Go to Walmart and buy, for each 10,000 gallons of pool water, 10 boxes of 20 mule team borax. Go to Lowes, etc. and buy 3 gallons of 31% muriatic, per 10K gallons. Begin adding 4 boxes of borax -- slowly to the skimmer with the pump on -- followed by a gallon of muriatic. After adding the last of the borax, add the last gallon, 1/4 gallon at a time, till your pH is between 7 and 8.

3. Buy 2 quarts of KemTek phosphate remover per 10K gallons: Kem-Tek 265-6 Pool and Spa Phosphate Remover, 1 Quart and a phosphate test kit: Taylor Technologies Inc K-1106 Test Kit Phosphate

4. Buy some GLB clarifier: GLB Pool & Spa Products 71404 1-Quart Clear Blue Pool Water Clarifier

5. Begin dosing with phosphate remover every few days to lower your phosphate levels to below 100ppb . Use small doses, per the label of the clarifer, to help quickly clear up the cloudiness from the phosphate remover.

6. Make sure you are running your pump 24/7, and brushing the black algae spots every 2 -3 days.

7. Make sure that your chlorine level stays at the shock level ALL the time. Use the Best Guess chart to find the appropriate level.

8. There are other things, you can do, but you'll have to report details on your pool finish & volume, and your pump and filter before I can mention those.

What you must understand is that NONE of those things will suddenly eradicate black algae. Black algae grows when you neglect the pool. But unlike other forms of algae, it sends roots down in fine cracks and crevices of the pool, where you CAN NOT reach, either physically or with chemicals. Even after you kill the exposed algae, the roots remain.

We don't normally recommend phosphate removal -- but if you lower phosphates enough, and KEEP them low, you will make it harder for the black algae to recover. We're not really sure why borates reduce algae's ability to grow, but it seems to. Chlorine will kill algae, but it has a hard time penetrating the film on top of black algae. Brushing helps.

The reason I mentioned all those things -- phosphate removal + borate addition + high chlorine adjusted for CYA, is that you can do all those and still swim. Plus none of those interfere with each other. By contrast, all algaecides are at least some what incompatible with chlorine (even polyquat, though it's the most compatible).

Other steps that depend on your equipment:
=> DE on your filter, but only if you have a sand filter. Helps remove precipitated phosphates
=> Brushing with an SS bristle pool brush, but only if you have a unpainted plaster surface
=> Dropping granular cal hypo on the algae, but only if you have a concrete pool and fairly low calcium levels
=> Dropping granular trichlor on the algae, but only if you have a concrete pool, and reasonable stabilizer levels


But NONE of this will matter, if you don't solve the original problem, of erratic chlorine levels, that resulted in the black algae in the first place.

I was using the pool perfect stuff, but havent put it in since I started at this site. I put 3 bottles of black algea tx from the pool store, I think that is what put me into this big mess that I just cleaned up.But it did cut down the algea by at least 90%. You are right, algea was growing all winter and I was too preoccupied with other stuff to care. Now I am paying for it. Been dumping chlorine in for weeks now. Don't have a good test kit yet, to measure high chlorine, just guessing and trying to error on the high side.Been wanting to do the borax just a little intimidated. I have a crappy cartridge filter. I am planning to change it out for DE soon, but first trying to get this algae thing and my pump problem handled before I start any more projects.

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Pool is plaster. filter is brand new intelliflo. Filter is cartridge. Volume I am unsure of. Post the formula and I will take measurements.

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I googled it and found a handy pool volume calculator by pentair. Says mine is 20,000 gallons.

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Do not use any more algaecide. No algaecide is completely compatible with chlorine; even polyquat, though it's more compatible than most.

The ultimate results of using anyone's phosphate remover will be the same, but apparently the Kem-Tek product I linked costs 1/2 to 1/3, per unit phosphate removed, of what the Pool Perfect products cost. Keep in mind that neither borax nor phosphate removal is a solution; both simply make it harder for black algae to recover from damage done by chlorine.

If you can post the EXACT model and make of your filter, I can possibly help you find a higher quality replacement cartridge that will do away with the need for a DE filter.

Note that I corrected the error recommending AquaChem strips. Fortunately, what is shown on the test page, it shows LaMotte and that's correct.

Honestly, I think I want to upgrade my filter. It is time for new cartridges and the pool store wants $200+ for a set. Now is the time, I can get a hayward pro grid for a couple extra bucks. Mine is a clean and clear plus 40. I hate it. No back flush. When removing phosphates I have to disassemble and clean sometimes daily. I think I will replace with a 60.

Not finding that model; here's the Pentair brochure: http://www.pentairpool.com/pdfs/cleanclearplusDS.pdf

There is a CCP420 and there are some Clean and Clear filters (no "Plus"), but the lowest they go is a CC50.

The Hayward Pro Grid is a DE filter. Have you ever used a DE filter? They are not very forgiving, and can be rather messy to service.