Algae Problem in our DE Filter?

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
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My Pool: 27' above ground w/Hayward DE Filter
Location: Pennsylvania

Algae Problem in our DE Filter?

Postby shawnandcarrie » Mon 26 Jul, 2010 20:27

First of all, let me say that we are fairly new pool owners. This is only our second season. Last year was a breeze, since everything was new and the water was fresh. A blissful swimming year! This year, not so much! We've been experiencing problems with the pressure rising on our pump/filter. There are days when we bump it 3-4 times. When this happens, we backwash the filter, change the DE, etc. - all of the maintenance you should do when this occurs. However, when we recharge the filter (I think that's what it's called - LOL), the water that comes out is green - almost neon green in color. Keep in mind, our pool water is not green. It is somewhat cloudy right now, but not green. Could we be experiencing an algae problem within the filter only? And if so, what's the best way to get rid of it? All of our chemical levels in the pool are okay - chlorine is good, we had to add some Ph increase last week, but for the most part it seems balanced.

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Algae Problem in our DE Filter?

Postby floridapooltech » Mon 09 Aug, 2010 01:42

the algae you are seeing when you backwash your filter is fairly normal, especially if you recently had an outbreak in your pool. The filter, if working correctly will keep all contaminants out of your pool, including the algae. Anything sucked into your pool cleaner or skimmer will also be in your filter if it is too small to fit in the skimmer or pump basket. Something that needs to be done in addition to backwashing, is every six months or so, you should be taking your filter apart completely (D.E. grids), hosing them down, inspecting them for thin areas, tears and replace them if they are worn. Just be sure that when you put it together, you are using the correct amount of D.E. per manufacturers specs. If you are using Perlite or other paper alternatives, it is usually 1/2 the amount needed compared to D.E.

Algae Problem in our DE Filter?

Postby Blazing » Sat 28 Aug, 2010 16:12

First off, you have the best type of filter in the world if it is maintained properly. D.E. filters filter down to about 6 microns, cartridge 12-15 microns, sand will only filter a particle bigger than about 30 microns. Since most algae common to pools is in the 8-16 micron range, there is nothing better for keeping your water clear. That said, let's address what is going on.

If you have a D.E. filter that is properly maintained, and you have proper water circulation and equipment operation times, even if you never add ANY chemicals, your water will remain clear. Yes, you will have to backwash your D.E. filter and recharrge it all the time. Yes yolur walls, steps, floor ... will all get to the point where they look like green shag carpeting from algae growth, but your water will remain clear and clean. This is why your water looks good, and you never see any algae in the water, yet your filter is green.

What this means is that, while you believe you are not getting any algae growth, you are wrong. You have it, but your filter is filtering it out. As a pool man of almost 30 years in the Phoenix Arizona area, and a trainer of pool men, my advice is that you find someone with about that much experience in your area and ask him what he does, after asking him how many pools he services a week, and how many turn green if the customer doesn't mess with anything and the equipment works as it should. Personally, I have serviced about 50 pools a week for 28 years, and one pool every 5 years gets some algae, and those are because the client did not follow my draining and refill recomendations.

If you were in Phoenix, I would tell you to get your pH at 7.6 -7.8 and keep it there, get your Chlorine Stabilizer (Isocyanuric Acid) to 100 ppm, and add 2 lbs. of granulated trichlor per 10,000 gallons, brush it all in, check after a half hour, and repeat the trichlor until the reading is off the charts on the high end when you test for chlorine. This should kill most of the current algae stock that is present in your pool.

If your free available chlorine reading ever drops below a 1.0 ppm, repeat the process. Keep salt cells cleaned. Keep salt levels at manufacturers recomended levels. If using tabs, get an adjustable chlorinatoe and adjust it so that half the weight of a new tab disolves in a one week period, and add enough tabs every week to maintain a 3.0 chlorine reading. When equipment is keept maintained, and all other levels are where they belong, I get the results I am describing above, and the men I have trained have seen similar results.
chem geek
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Algae Problem in our DE Filter?

Postby chem geek » Sat 28 Aug, 2010 22:43

In general (i.e. for virtually ALL pools, not just a subset with certain characteristics), 3 ppm FC with 100 ppm CYA is not enough to prevent algae growth unless there is either supplemental algaecide or phosphate levels are kept low or there is regular shocking to higher chlorine levels. Since you are doing drain/refill of your pools periodically, and your fill water may not have phosphates in it, then you are lucky to have relatively nutrient-poor water, but that is not the case for thousands upon thousands of pool owners.

See this post I wrote in response to another one you wrote in a different thread for more info.

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