Came home from Afghanistan to a green swamp of a pool

[NavyChief]

Recently finished up a 13 month tour in Afghanistan, all was well until I got home and found out there was a different war to finght, the war on algae. MY above ground pool, 15k gallons or so, was green as the day is long. Added some acid to drop the Ph and also plenty of liquid chlorine. Pool now is a loverly milky blue color. Have added 10 gallons of chlorine last week and today still am reading close to 3 ppm. Also added a water clarifier. Pump has been running no stop for close to two weeks. I have a sand filter with Zeobryte and a hayward pump. Backwashed several times up to now and am maintaining a reading of less than ten, which is good for this unit. Before I left for Afghanistan, all I had to do with this pool is dump in 2.5 gallons of chlorine on Sunday and this baby was a clear as could be, not so much now. Ideas?? Thanks

[PoolDoc]

The milky blue indicates that the algae is mostly dead, but that the algae 'corpses' are now floating around in your pool. Filtration will remove it, in time. Be sure to run your pump 24/7, and, if there is ANY way to do so, slow the flow down.

I'm assuming your have a sand filter, filled with Zeobrite, instead of sand? The problem here -- typically -- is that your pump is over sized relative to your filter. This is common, that we almost never see exceptions to this pattern. ALL of the manufacturer filter & pump combos for above ground pools exhibit this problem.

Over sized pumps are not good with any filter, but are especially bad with sand filters, causing at least 3 problems:
1. Dirt, and especially algae, is pushed THROUGH the media, and back into the pool.
2. Excess flow causes you to lose filter media each time you backwash.
3. And, it wastes electricity!

You may also want to open your filter and make sure that you haven't lost so much media that your filter is pretty much not a filter.

And, be careful with the clarifier: a little can help, but too much will actually work in reverse of what you expect, and cause the algae to remain suspended!

Finally, don't let the chlorine drop. You may have all the algae in the water, but until you see the pool, you can't be sure you have all the algae in the cracks and crannies . . . and if you let the chlorine drop, it may 're-bloom'.

PS. Thanks for your service. Are you a corpsman, a SEAL, or something else? I wouldn't have thought too many Navy chiefs were on the ground there. My first cousin was there, fairly often, up till two years ago, when he retired as commander of MARSOC. He's the same age as I am, give or take a couple of months . . . and blew out his knee for the final time, after deciding he should try to keep up with some of his guys during a training exercise that involved going over a wall. He's got a stainless steel knee, now. Of course, that's a lot better than coming back with no knees, like a lot of guys have done.

[aylad]

I also wanted to thank you for your service. You guys are incredible!!

Just a comment to add to what Ben said--the reason you were able to maintain chlorine before was probably because you had a good stabilizer level. However, after an algae bloom, many times that stabilizer level will fall, and will not retard the sunlight consumption of your chlorine.

I agree that you shouldn't let the chlorine drop--assuming your CYA level is zero, then you should take the chlorine up to the 12-15 ppm range and hold it there until it clears up, or until you can measure the chlorine at night and again in the morning prior to the sun hitting the pool, and only lose 1 ppm or less chlorine overnight.(See the best guess chlorine page linked in Ben's sig for more on that subject.) It will help if you get a current stabilizer level, so you know where your chlorine levels need to be.