Sand Filter issue with cloudy dust

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nivek911

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May 13, 2007
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I have a Hayward 166 Sand filter and Zeobrite as the media. I've been dealing with a problem ever since the pool was installed 2 weeks ago. I had cloudy water after the Zeobrite was backwashed, and found small white material in the bottom of the pool.

After a close to a week with no improvement, I called the PB and he suggested that he maybe didn't get flushed out enough initially. So I backwashed, rinsed, and added SeaKlear clarifier per his recommendation. Over the next couple days, the water cleared, and was crystal clear.

Last night, I saw some grass clippings in the lower pump basket. I shut the pump off, turned the shut off valve on the skimmer side off, turned the filter to OFF to prevent a backflow of water since there is no return side shut off valve. I cleaned the basket, put the top back on , turned the filter to FILTER, turned the skimmer shutoff ON and started the filter. I checked for leaks, stood up and a cloudy white mess was blowing out my return line again.

So my question is... do sand filters all do this when they are shut off? Were my steps wrong?

I wouldn't think so, but just wanted to double check. Now I have to start all over again cleaning up the pool. What's really interesting to me is that the filter had been at 22lbs pressure for almost a week (since the last problem) and as soon as I put it back on filter and started the pump, it dropped to it's clean pressure of 18lbs.

Any advice you can offer would be helpful. Thanks
 
This one is something of a puzzler. My best guess, wild speculation really, is that this white powder is too small to be filtered out under normal conditions. The SeaKlear got it to clump enough that the filter was able to catch it. Then as it sat in the filter the SeaKlear broke down slowly but water pressure still held everything in place. When you turned the water off everything got stired up and it stopped clumping. Turning the pump on again washed it through the filter. If I am right you will need to add SeaKlear, or a similar flock agent, and then backwash the filter throughly once the water clears.
 
Good to hear your pool is clearing up and all is coming along well.
When a filter collects dirt, the dirt creates a thin layer on top of the sand bed. When you are filtering, there is continuous downward pressure on this dirt, holding it in place on top of the sand. Because the pressure is continuous and does not really change, everything pretty much stays in place. The more dirt you collect, the better the filter works because you are actually creating a finer filter on top of the sand filter - this finer filter is held in place by downward pressure.
Once you shut off the pump, this downward pressure is released and some of the dirt will wash into the still turbulent waters above the sand bed. The particles are so fine, they tend to stay suspended for a longer period of time. Even after backwashing, you will have the cloudy turbulent waters in the top of your filter - this is why we rinse after backwashing, to clear out the dirty water trapped over the sand bed.
When you turned the system back on, the initial pressure from the pump blows some of that settled and suspended dirt through the sand to your return. (because the dirt is actually finer than the sand or Zeobrite)
This is perfectly normal, and in the grand scheme of things, it is maybe 1 ppb (part per Billion) of dirt blowing back into your pool.

I guess you could compare it to a plugged toilet, individually, the things that plug a toilet are each "normally" smaller than the actual toilet drain opening, however, collectively, they are plugging the toilet. When turning the pump on, you are essentially placing the plunger into the toilet and pushing all that collected material through with a big burst of force.

With a pretty dirty filter, the dirt that comes through is proportionally more compared to a cleaner filter. The next time you do this, if the filter pressure is up more than 2lbs from your clean pressure reading, you may want to backwash while you're at cleaning the basket.
 
Thanks Jason and Matt for the replies. To followup with a question then based on what Matt wrote:

Is the reason why it released was not due to the pump being shut off, but more due to me setting the filter / skimmer to OFF thereby releasing the pressure of the water in the pool?

My point is, there seems to be a lot of people that run sand filters on a timer which shuts off their pumps. If this occurred everytime I lost power or turned off the pump due to a timer, I'd never have clear water. I guess this also would be true for people that put DE in their Sand filter, as that would release everytime they power off the pump.

Is my logic right here, or am I missing something?

Also, I use skimmer socks, so this morning, the sock was stuff full of material that I assume the SeaKlear collected. Should I run without a skimmer sock when I use the Seaklear or is it still OK to use the skimmer sock?

Thanks again.. sigh.. I'm beginning to think DE or Cartridge is less work at this point...
 
I think you have a problem with the internals of the filter. I have a Hayward sand filter and basically do the same as you do and have never had anything like you have. I am using regular sand and adding a little DE. Since the pool is only two weeks old, I would get the builder out there to fix it.
 
I had something similar once on my sand filter and it was the gasket between the valve that runs and the valve body. With the gasket gone sand/Crud would leak around through the valve.

Not sure if this could be your problem.

dave
 
Most likely, it is from shutting it off, some air gets introduced causing even more turbidity in the space above the sand.
Personally, from what I read about them, I think DE filters are a lot more work.
I think not using the sock when picking up flocked material is a good idea.
Many of us run our sand filter with a coating of DE on top to help catch and keep fine debris - replace after backwashing - I think there's a sticky explaining the details...
 
After giving it some more time, I'm calling the PB again tomorrow to look at the filter and/or replace. We lost power at the house and the filter went from 21lbs last night back to clean pressure of 18lbs when I came home. Of course, the pool bottom has junk on the bottom again. Sigh...

Anyhow.. Matt/Brittmer, you both run Sand with DE.. when you shut off your pump and turn it back on after say 5 minutes, does the pressure in the filter return to the cleaned pressure? I sure the answer is no, but just want to clarify so I can have more information for the talk with the PB.

I also assume from Matt's comments that you may get a 1 - 2 second puff of cloud out of the return, but it shouldn't last longer than that correct?

Thanks!
 
mine might blow dust for 10-15 seconds - strong at first, then less and less, it's normal for the pressure to drop a bit, but not right down to "clean" pressure.
Have them look at it, it's better to get it fixed while it's new, then to be stuck with a problem.
 
My sand filter has never blown anything out through the returns. I think there is something wrong with your filter or it is undersized. The spider gasket suggestion from hdtv is a good one; have the PB sheck that out.

18 PSI is a little high for a clean pressure. What size pump and filter do you have? Open up the filter and look at the sand. Any channeling that you can see?
 

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Thanks Kurtv and Matt..

Yeah, HDTV's comments made a lot of sense to me. I have a 1HP Powerflo Matrix pump with the Hayward 166T filter that hold 100lbs of sand. I assume they added 50lbs of Zeo.

Also, I can cut down the pressure by turning down the skimmer shut off valve.. I think the lowest pressure it will go without starting to sound wierd is 15 lbs pressure.

It's a 24' Above Ground pool. Thanks!
 
My filter clean pressure is 15lbs dirty is 25lbs sometimes i backwash for ten minutes to get rid of excess water sometimes just a half minute. Have replaced sand twice in seven years and have never had anything like you are describing happen. I rarely rinse although the description above is what I was told rinse was for by the local pool store.
 
To give an update and closure on this issue, the PB came out and replaced the filter and put in new Zeobrite media. Later that day, I vacuumed off the dirt/zeo/whatever off the bottom of the pool.

That was two days ago, and I just checked tonight and I have just a couple little spots where I probably missed with the vacuuming.

Whatever the problem was, it left with that old filter. I do notice the new filter (with the old pressure gauge) never moves from 18lbs. The old filter would wiggle the needle from 18 - 20lbs when it ran.

Finally a clear pool that I don't have to vacuum every night.
 
nivek911 said:
To give an update and closure on this issue, the PB came out and replaced the filter and put in new Zeobrite media. Later that day, I vacuumed off the dirt/zeo/whatever off the bottom of the pool.

That was two days ago, and I just checked tonight and I have just a couple little spots where I probably missed with the vacuuming.

Whatever the problem was, it left with that old filter. I do notice the new filter (with the old pressure gauge) never moves from 18lbs. The old filter would wiggle the needle from 18 - 20lbs when it ran.

Finally a clear pool that I don't have to vacuum every night.
Click to expand...

What filter was it replace with? Same Hayward or bigger?

I have the same problem with my Sta-Rite Cristalflo 200#. I have checked and triple check everything. It has been doing this since new. I thought I was overdriving it with a 1 1/2 hp pump supplied with the pool, but have since switched to a 3/4 2-speed. Same problem. Filters great on low, but kick that baby on high and watch that cloud and all the hard work blow right back in the pool. Run it on high with the timer and the bottom is always dirty.

I was thinking of buying a Hayward S210T if I can't get this one figured out. Its been over a year, so I don't see that happening. :cry:

Thanks
BD
 
It was replaced with another Hayward 166T. If I had to do it over again, based on the reading here and PF, I'd probably request a larger filter for added filtration. Just curious but:

Have you called Sta-Rite about it? What do they say?

Do you have Zeo or Sand?

Do you run it 24x7 or on a timer?

Did you put DE in it by chance, or is it just plain media?

The PB handled the problem as well as I would have expected, as they offered solutions and when those didn't work and I specified that I wanted a new filter, they replaced it without question.
 
I haven't called Sta-Rite yet. I guess I just love to torture myself. :lol:

I'm running it with sand. I have tried the DE trick and it does do a fine job of making the water crystal clear. But... I have to run it 24/7 for it to stay that way. If I were to shut it down, either running on the timer or turning it off for other reasons, the DE and the rest of the dirt blows back in the pool. It is probably a good 15 second cloud coming from the return. No bugs or larger debris as far as I can tell. This is with the 1 1/2 hp that came with it and the 3/4 hp 2-speed on HIGH.

With the pump on low, it filters great and does not seem to be affected by the timer cycles on and off. But that means I have to backwash everytime before vacuuming on HIGH.

I wonder if I some how got bad sand? It was U.S. Silica from the pool store. Maybe try new sand or Zeobrite?

Cheers!
 
You need to have the correct size sand. I would be surprised if a pool store sold you the wrong size but you never know. Pool filter sand is very fine, finer than play sand or any beach I have seen. I would check to be sure you have enough sand. If you have too little sand it is much easier for things to get through.

It is possible for sand to get channelized, paths through the sand that allow larger particles through develop in rare cases. If you open up the filter and look at the sand this will be fairly obvious, backwash before opening. The sand should be lose, any clumps should be easy to break up. If there is significant crusting or solid clumps that won't break up easily then the sand should be replaced. While you have it open you can gently wash out any debris that has accumulated. You should be able to gently push a slowly running garden hose into the sand to rinse everything out and redistribute the sand evenly. Be careful not to break a lateral, they will be buried in the sand, use gentle pressure and let the water do the work.
 
Thanks for the reply.

I loaded the filter with 200# as called for by Sta-Rite. It was this stuff I got from the pool store http://www.u-s-silica.com/lighthouse.htm

lighthousebag2.jpg


It has done this since new. The filter is about a year old including the sand. No clumps or channeling in the many times I have had it open. The laterals are/were new and not broken, stand pipe looks good with tight fit and the spider gasket looks good.

I think i'll try some new sand, maybe different brand from different pool store.

Thanks for the help.
 

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