Pool just will not clear up

lebaige

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May 20, 2007
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#1
Quick story, we opened our pool almost three weeks ago to a massive slime pit courtesy of the last owners. It's a 24' AG with a 150lb sand filter and a 1.5hp pump. Current numbers from our Taylor test kit:

FC: 13
CC: 0.5
TA: 100 (was 230, brought it down via acid and aeration)
CH: 230
pH: 7.0 (seems to sit normally around 7.4, it's still coming back up from acid treatment)
CYA: ?? (Water is too cloudy to test it, I've put around 4lb of granular CYA in there which should put it around 40)

I've been shocking it nightly with 6% bleach. I'm losing about 5ppm of FC a day to sunlight still, which surprises me based on what the CYA level should be. The water went from green to blue grey, then back to green again after I vacuumed for a few hours a week ago. There was a bunch of leaves and crud on the bottom I couldn't see and a lot of dirty water shot right back out of my return line. I vacuumed and leaf raked for most of the day and I'm pretty sure I got the bulk of it.

Since then I have been brushing daily to stir things up and continuing with the shock / filter treatment. The water is back to a milky blue, and I can see specs of dead algae floating in it that seem to be sticking together; they were finer before. I have maybe nine or ten inches of visibility if that.

It just doesn't seem to be improving anymore and I'm very frustrated. I disassembled my filter thinking it might be broken and I can't find anything visibly wrong with it. I backwash from time to time but the pressure builds up VERY slowly, which makes me think either the particles are too fine for it or it it's just malfunctioning somehow. I'm very close to just buying a new filter / pump combo.

Anybody have any ideas? Help!
 

JohnT

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#2
The dead algae will also consume chlorine, regardless of your CYA. If you aren't making progress, a dose or two of the clarifier that Walmart carries might finish the clean up.
 

JasonLion

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May 7, 2007
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#3
It can sometimes take more than a week for the water to clear after you beat the algae. If your FC level has been holding overnight for more than a week I would expect things to be better than what you describe. How long has it been since the day of vacuuming and raking? If it has been more than two weeks I would start to suspect that the water isn't really going through the filter, possibly a problem with the main valve. When you backwash the filter does the water run dirty for a while and then clear, or is it clear almost right away?

Another possibility is that your CYA level is really much higher than you think and you haven't actually gotten it to shock level, particularly given that the water is still green. A test strip would give you an idea of the CYA level, not especially accurate but ballpark. One trick to get an approximation of the CYA level with the usual test is to pour some pool water through a coffee filter and then do the CYA test with the filtered water. The result won't be especially accurate but it should get you in the ballpark.
 

lebaige

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May 20, 2007
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#4
The water isn't green at all anymore, that happened about a week ago when I vacuumed the bottom. It came from all the crud that was sitting down there with the leaves, which are gone now. It's just cloudy with tons of dead algae now and seems to be content to stay that way. You can clearly see it floating around when you get down close and look.

I backwashed yesterday after having not done it for four or five days (I wanted to let the thing dirty up and see if the pressure would build up) and it came out brown for maybe twenty seconds and that was it. I did it again today and it was virtually clear from the start.

It's just odd, as I disassembled that entire valve and everything is working as advertised. I can't find the problem. I've been avoiding using clarifier as it seems gimmicky to me but I think I might just break down and see what happens.
 

duraleigh

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#6
Lebaige,

Chlorine, brought up to shock level, will clear your pool.

Based on your CYA approximation, you need to bring your Cl level up to at least 15ppm...20 would be better, and keep it up in that range until your pool clears. If your dropping 5ppm overnight, the Cl is working on impurities in your water. Bringing the Cl to shock value will help make your Cl more effective and speed the process.

The only unusual thing I see in your post is the infrequency of backwashing....that's pretty unusual.

I assume your getting normal flow from your returns. Curious, what type of filter do you have?

In summary, get the Cl in there. I suspect you haven't been quite reaching breakpoint (shock). Once you do, and sustain it, your pool will clear.
 

lebaige

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May 20, 2007
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#7
I have a piddly little Dough Boy Media Master 150lb sand filter. I have a feeling the pump it's coupled with (A Doughboy Power Pak II 1.5hp) is too strong for it, although the pool stores that sell them claim the GPM for each are compatible. I'd like to replace both with a little .5hp Hayward and a 250lb filter but I don't really have the funds to do so at the moment.

I'll keep pumping the Chlorine level up I suppose, it's just very frustrating and starting to get pricey. The organics in the pool seem quite dead at this point, it just feels like they aren't being filtered out.
 

duraleigh

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#8
lebaige said:
I have a piddly little Dough Boy Media Master 150lb sand filter. I have a feeling the pump it's coupled with (A Doughboy Power Pak II 1.5hp) is too strong for it, although the pool stores that sell them claim the GPM for each are compatible. I'd like to replace both with a little .5hp Hayward and a 250lb filter but I don't really have the funds to do so at the moment.

I'll keep pumping the Chlorine level up I suppose, it's just very frustrating and starting to get pricey. The organics in the pool seem quite dead at this point, it just feels like they aren't being filtered out.
I understand your post perfectly and am not in disagreement with you. In particular, AG pools frequently have too much pump and too little filter because it's an easy, cheap marketing technique.

I understand about the cost, too. That said, I think you have no alternative. The cheapest, simplest way to clear a pool of contaminates is Clorox. Once you get it clear, your Cl usage will drop dramatically and you'll find your costs dropping quickly to practical levels. Are you putting the Cl in in the evening? You'll get the most bang for your buck by doing that and then bringing it back up the next morning. I have found that that evening and morning application seems to give me the best results (least usage of effective Cl)
 

lebaige

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May 20, 2007
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#9
Well, I can actually see the bottom at this point. As it turns out my wife started putting clarifier in every three days without bothering to mention it to me. I'm honestly not sure if it worked or not but there you go. We've also had a lot of water turnover due to rain and backwashing. Couple that with regular vacuuming and shocking and I guess the water gave in. Hopefully we'll actually be able to stop shocking here in the next couple days and use the pool this weekend.