So ... a 1000 gph filter pump WON'T clear dead algae out of a pool. What next?

Jun 8, 2017
117
New Orleans, LA
After having our pool (see signature) go green over the winter ... I've just finished with SLAMming the pool. All the algae is dead and I'm ready to get all that detritus out of the pool. The green color has been gone, so now I'm trying to turn pale milky cloudy water back to clear. Keeping the chlorine levels high to prevent a relapse ... the pale milky color has held firm for almost two weeks straight.

Bought a new filter pump (same as described in the signature, see pic here) from the local sporting goods store. For our small backyard pool, the original 1000 gph filter pump that came with it actually did a pretty good job over the first two years of owning the pool. But I never actually needed the filter pump to clear dead algae out of the pool. Since the original filter looked so cruddy, I just decided to replace it with a new one expecting to have no trouble clearing out the dead algae.

Not so fast. The new pump, when it's got a new filter, pumps great for about 20-30 minutes. The pool's intake jet is nice and strong at first. But then, before long, the intake jet slows to a faint trickle and I notice a gurgling air pocket in the clear tubing coming from the intake-jet 'mouth' of the pump (the 'mouth' that feeds filtered clean water back into the pool).

I thought the pump itself was failing mechanically. I disassembled all the tubing and equipment, reattached everything, PUT IN A NEW UNUSED FILTER, and started over. SUCCESS! ... but only for another 20-30 minutes.

I learned through trial and error that the problem really is the filters getting 100% clogged with dead algae too quickly. The pump runs nice and strong with either (a) no filter cartridge or else (b) a brand-new filter cartridge.

...

So at this point, what are the options for clearing the pool of dead algae debris? I hate to substantially upgrade the filtering system on a cheap pool (~$350 in 2017), but at the right price point I would consider that. Otherwise:

a) Can I hire a pool-cleaning service to come out and vacuum the pool's water? Haven't priced it, though. Could maybe borrow a pool vacuum from someone ... have to ask around.
b) Can I stick with my cheap filter pump, but do something to the filters to make water pass through a little more freely a little longer while (hopefully) still getting decent filtration? Maybe cut some slits or poke some holes in the filter cartridges paper 'fins'? To prevent them from 100% blocking the flow of water?

Any other potential solutions I'm overlooking? I have stuck just with chlorine (+ a little CYA) while SLAMming and want avoid flocculents, algaecide, clarifiers, or anything like that. But I don't know ... does it sound like I'm at the point of needing some kind of additional chemical help?

Thanks in advance for any advice anyone may have.
 
Intex cartridge type filters will be a pain to remove dead algae. If you want you can upgrade to a sand filter, which gives you the ability to backwash. Milky water means you still have algae and you need to keep SLAM Process levels until you pass the Overnight Chlorine Loss Test.
 
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Do not cut slits in the filter cartridge! That will just make them useless. I don't know if a pool service will be willing to help you. Most of them use the pool owner's equipment to vacuum so that won't help you. The only way you are going to get better filtration is to get a better filter. The intex sand filter/pump combo works really well for small pools and you can get one new for less than $200. You may be able to find one used on Craigslist.

You could buy several cartridges and swap them out every 20 minutes. Rinse one off while the other is filtering, but with the speed they are clogging this would be an all day task.

Draining and refilling the pool may be a better option if you do not want to invest in a better filter. Chemically there is nothing else you can do. You have algae debris in suspention in the water and it must be removed by filtering or draining the saturated water. You cannot use floc with a cartridge filter, period. A) It will ruin your filter, and B) You cannot vacuum to waste. Clarifier will not help either. Algaecide is to prevent algae, it doesn't remove it from the water.
 
Thank you, zea. The sand filter prices don't look so bad, though I'm curious about the wide variation in prices for similar equipment.

Also, I have to worry about the sizes of fittings and tubes. Really wish Intex would stick with one standard size -- to go with a sand filter, I've got to figure out a way to convert 1.5" tubes to fit onto the pool's 1.25" fittings.
 
Bord, why not try this
I've been using it for a week now, since I opened my new pool, and it seems to do a good job. PLUS you won't be throwing out filter cartridges. You can get spare filter media from the website so you could have one soaking to clean and another in the filter filtering.
 
Richard, good advice on checking for an aftermarket filter.

...

Wobblerlorri, that looks useful in ordinary circumstances. The trick here, though, is that even with having spare filter material cleaned and ready ... I still have to spend many hours in a row babysitting the filter pump and changing out the filter material every 20-30 minutes or so. Hoping that with a sand filter, I can just set it up and forget for however many days it will take to filter out the dead algae debris.
 
Do not cut slits in the filter cartridge! That will just make them useless.
Well, maybe not big honking gashes or anything extreme. But I don't know ... surely the filter cartridges would still generally function with some pin pricks or a very few small 1/4" slices (along, not against, the grain of the fins!) cut in them?

Right before I change out the tiny filter pump for something better ... I think I will try out some nicked filter cartridges just to see what happens. For science.
 

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Any visible hole that you make in the filter will allow the debris that you are trying to catch to pass through. Holes big enough to make a difference in the rate of water flow will allow a lot of debris to just circulate in the pool without being filtered out. You will have better water flow at the cost of lousy filtration.
 
Hello on your statement of (Hoping that with a sand filter, I can just set it up and forget for however many days it will take to filter out the dead algae debris) while using a sand filter is a much better option than the cartridge filter system that you now have, it is not maintenance free system. you still must keep check on the filter pressure and back wash when pressure reaches a certain point usually on mine about 10psi above clean pressure. I agree this is a much better option that you now have but it not something you can hook up and leave for days under your conditions. once water is clear of dead algae then yes it can go for much longer periods without having to back flush. But still should keep check on filter pressure.
 
Hello again: I forgot to mention the statement you made about cutting holes or slits in your filter. If your going to do this you may as well just take the filters out and run with out them, all you will be doing is recirculating water and dead algae. Wher it will catch some it wont clean water enough to solve your problem and lead to more problems. just a though. there is really no solution other than cleaning water completely. Just a thought
 
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Intex cartridge type filters will be a pain to remove dead algae.
I have been working on it with the ol' cheapo cartridge filters since Friday evening. At first, I was getting only 20-30 minutes of filter time before the water flow stopped. Now it's up to about an hour, plus or minus 10 minutes. I have four filters going in a filter-wash-dry cycle ... they vary in how much time they last.

While it is definitely the hard way, I am making headway. The milky water is gone. Now the pool water looks kinda like well-used hotel pool water, if you know what I mean. Better than milky, but not yet to clear.

Unfortunately, this whole process has to be monitored -- I won't be able to continue overnight -- so that's 10 hours or so of filtering time I can't use.
 
Bah ... thought I was going to be able to cheap it out and finish the job with the small pump and the paper cartridges ... but in a day and a half since I last posted, the pool water hasn't been improving much. Sometimes it looks like it's getting a little clearer (can see objects placed further away from the surface), but I'm not sure if I'm convincing myself that it's getting better or if it REALLY is.

Cartridges are still collecting plenty of dead algae. And it's been taking longer and longer for the filters to clog ... around 2 - 2.5 hours now.

All that said, I've bitten the bullet -- a sand filter is on its way. At this point, I need to get the pool ready in a matter of days, not weeks
 
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Good Luck!!! I think once you get the sand filter up and running you will be very glad you went ahead a got it.

I sure hope so.

Meanwhile, the pool continues to clear gradually. Last night, for the first time since this SLAM started, I was able to run a paper filter overnight without the filter completely clogging. This morning, I was able to see a hazy image of the brush head while it was down at the bottom of the pool (3.5 feet deep). Still not crystal-clear -- and the Intex-pool blue-squares pattern is not yet visible at the bottom of the pool -- but it's coming.
 
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Ho-lee moley -- as of late yesterday afternoon, I can see the bottom of the pool! Still some hotel-pool haze, but the blue-squares Intex pattern is unmistakable. The paper filters and 1000 gph are going to do it!

The sand filter pump is coming today. At least the paper cartridges have already done the heavy lifting.
 
Wobblerlorri, that looks useful in ordinary circumstances. The trick here, though, is that even with having spare filter material cleaned and ready ... I still have to spend many hours in a row babysitting the filter pump and changing out the filter material every 20-30 minutes or so.
Ended up doing the bolded anyway last weekend, at least for one day. But it has paid off -- the paper filters progressively took longer and longer to clog, and it only took about 20-24 hours** of "babysitting" the cartridge filtration to get it to the point where filter changes were down to 3x a day and I could run the pump overnight.

At this point, the water flow at the intake jet doesn't appreciably weaken even after 12 hours. I changed to a reused washed filter, anyway, just to get the dead algae debris out a little faster.

** not 20-24 consecutive hours -- pump was turned off the first three nights to avoid prolonged and unmonitored pump motor use once the filter got to 100% clogged with no water passing through.
 
Sand filter ran for 12 hours starting at 6:30 pm yesterday. The pool water is at the point where I can see small bits of dirt on the bottom. The water’s surface is lustrous, but looking through depth to the bottom there’s still a little haze left to clear.

Waiting for “TFP clear” water at this point. Just need chlorine and patience, I guess.
 
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