Re: First test readings of season
We've seen repeated cases of "never ending fog" in pools with spring algae. It's not super frequent -- fortunately -- but it happens every spring.
-- Let me remove a side issue first -- @stma: if your pool turned from green to blue and than back to green, on use of "Metal Free", you have problem with metals (iron or copper) that is independent of any problem you have with cloudiness. Put another way, if your pool is cloudy, you have TWO problems: one with the metals in the water and the other with whatever is causing the cloudiness. --
@michael3: Before I start giving you guesses, let me say first that I do *not know* what the cause is . . . but
1. I can not recall a case of this happening on a pool with a DE filter;
2. It's most often AG pools;
3. Posters are typically coming to us some time AFTER the problem has become obvious;
4. Often, there has been prior use of a variety of algecides, flocculants, and clarifiers.
5. The problem gradually resolves itself, but sometimes it takes weeks.
6. Once the problem exists, slowing the flow (which creates a desirable little pump / BIG filter situation), doesn't seem to solve the problem quickly.
#1 tells me the problem is something not being filtered. Unlike cartridge and sand filters, DE filters are a positive filter -- excess pressure and flow may damage the filter, but will not usually push the dirt through the filter.
#2 suggests that the problem may result from the typical BIG pump / little filter problem that exists on AG pools, and that this problem is not so common when the filter is properly sized.
#3 - #6 suggests to me that, once the problem has existed for a week or more, there may not be any easy fix.
Here's what I think happens:
1. Pool gets algae.
2. Pool owner kills algae, but not all at once.
3. Dead algae is forced - due to BIG pump - through the filter. (<= I'm guessing, here)
4. This breaks the dead algae particles into fine dead algae fragments, so
5. Now the particles are TOO FINE to be removed, even when the flow is slowed.
6. Complicating the situation, use of flocs, clarifiers and some algaecides, actually work IN REVERSE, suspending these fine particles in the pool.
Here's the best I think you can do:
1. Add an overdose of chlorine -- with CYA=65, a 20 ppm dose would be good. (2 gallons of 6% bleach on a 6,000 gallon pool)
2. Turn the pump off and leave it off for 48 hours, and do NOT swim or disturb the water. (If you are lucky, the algae or other particles will begin settling to the bottom.)
3. Examine the pool. If the particles are settling, leave the pump off, and maintain chlorine by pouring bleach around the pool. It MAY TAKE A WEEK!
4. Once settling is complete, vacuum to waste. If necessary OVERFILL the pool. Be sure to move the vac head VERY SLOWLY to avoid stirring up the particles. If necessary, vacuum partially, refill, and vacuum so more. Be CAREFUL NOT to create water movement with the vac head, vac pool, vac hose, or water hose.
5. If you are not lucky, and nothing settles, simply resume normal operation but throttle flow through the filter to 1/2 or less of normal . . . and then be patient.
6. Alternatively, if you can drain and refill safely, do that.
There is an alternative approach: replace your sand or cartridge filter with a DE filter.
Sorry, I can't offer a better solution!
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