Sand Filters - are they really this bad?

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C

creativour

0
Apr 22, 2011
26
North Florida
Hi folks,

The only filter I've ever had to deal with is a sand filter and I'm wondering if there's something wrong with mine or if they really are this terrible. Here's what happens:

There is always fine silt collecting in clumps on the bottom of the pool. When I vacuum it up, I see it spewing out of the returns almost immediately. The next day, the clumps of silt are right back where they were. What a waste of time. I know the silt particles are very fine, but my gosh it seems like it's not even making it to the sand.

Here's what I've tried:
- Took apart the multiport to see if the water was somehow bypassing the filter (everything seemed fine)
- Added a scoop of DE to the skimmer (it immediately spewed out of the jets too)
- Tried some homemade slime-bags on the returns (this worked the best for the silt, but it seemed to hinder the circulation)
- Replaced the sand (didn't seem to make any difference, but I did it mostly to check out the laterals - they seemed okay, i guess)

I'm wondering about getting a cartridge filter to replace this lousy excuse for a filter. Do you think it would take care of my silt problem? I understand the pros/cons of each type of filter, but I also don't know the "micron" size of this pesky silt that won't go away.

I just can't imagine that sand filters are really this bad...

Thanks for your input! Love this forum btw.
 
This certainly does not sound correct. There is no way everything should be visible coming out of the return jet.

Problem is, sounds like you have checked all the usual suspects: leaking multiport, clumpy sand, laterals

I have to suspect that there is still something not right inside the filter allowing the water to bypass the sand.

While sand is the "worst" as far as capturing small particles, they are still capable of clearing a pool ... especially if you add a little DE.
 
Something is broken about your filter. Normally I would say your sand is getting channeled, but if you replaced the sand then it seems unlikely that it got channeled again right away. A broken riser pipe could do what you describe, as could a couple of other internal components if they are broken as well as possible broken components in your main valve. One way or another something is allowing dirty water to go to the output without passing through the sand bed.
 
I just can't imagine that sand filters are really this bad
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They aren't. There are thousands of users on this forum with sand filters whose water is crystal clear.

Did you examine the laterals carefully when you replaced the sand? It sounds like you have done the right things but something is wrong with your system if you are getting silt returning to the pool, regardless of the type of filter you have.
 
Thanks for the replies!

I'm a little relieved that this is not normal behavior for a sand filter. I think it's time to take the sand out and check out what's going on in there.

I did check the laterals a while back when I replaced the sand, however I'm not sure what I was supposed to be looking for. Since then, I also did some replumbing and pump replacement that resulted in moving my equipment pad about 15 feet around the corner of my house. Maybe I jarred something out of place when I moved the filter (it was unbelievably heavy). Although it didn't work all that great before I moved it either (hence why I replaced the sand in the first place), so maybe that's not it.

JasonLion said:
A broken riser pipe could do what you describe, as could a couple of other internal components if they are broken as well as possible broken components in your main valve.
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Can you point me in the right direction for some guidance on how to check the components in the filter? It's a Hayward S200.

257WbyMag said:
I'm still leaning toward a loss of integrity in the laterals on this one. Are you certain that your laterals are intact?
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Do you think this would be obvious? I think i'll be taking the sand out this weekend to see what I can find...
 
A couple of years ago I replaced my 1989 model sand filter. I had the same problem as you. I suspected broken laterals or seals, but could NOT see any evidence of this after emptying out all the sand. Given its age, I did not hesitate replacing it and starting new, although they are extremely simple in design.

I love my sand filter, and personally I would not consider switching to DE or cartridge for my pool.
 
While I cannot comment on your filter exactly, I can say that our experience and frustration with a sand filter is the same. We literally tried the same things...we even changed from a 2hp pump to a 1hp 2 speed.

What we discovered in our situation is the way the water sprays over the sand is too direct so it causes channeling. Basically as soon as the pump was turned on high, the spray from the multiport(where the water enters over the sand) was too strong and would blow a hole over the laterals. Everything we just cleaned out came back into the pool. My dh tried to modify the "basket" where the water sprays, but it was still too direct over the sand.

I also don't know how many pool owners experience silt, but I just don't think a sand filter can clean it out, it's just too fine. Skimmer socks were a big help.

This is long winded and may not even apply in your situation, but I thought I'd share the things we checked and see if the channeling thing could be your case. We were able to take the multiparty off and shine a flash light in too see it...it was full of water. When we drain the water out of the filter, it would mask the problem.

Good luck!
 

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I also don't know how many pool owners experience silt, but I just don't think a sand filter can clean it out, it's just too fine.
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I keep this picture on my desktop and post it 3-4 times each swim season.

This pic is taken through 7 or so feet of water, sand filter 7-8 years old with original sand, no DE, no skimmer socks, no nothing.......just sand.

Each pool and location presents it's own set of problems but a sand filter, functioning properly, should be adequate in each situation[attachment=0:1pkm8iij]DSC00049.JPG[/attachment:1pkm8iij]
 

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I have about the same clarity...but not as sparkly as Dave's :lol:

A properly operating sand filter captures silt just fine. The only time you can visually (ie.naked eye) see a difference in water clarity in a sand vs DE or cartridge filter is at night with the pool lights on. If you live in an area prone to wind/dust, you'll have silt accumulate on pool floor regardless of the filter, until it is vaccumed up.
 
You moved a sand filter, full of sand, 15-feet & installed it at the new location? Um, yeah, I second your suspicion that you bumped something out of place or maybe busted the laterals. I'm with you on your idea to crack open the filter & check it again.

Good luck!
 
So just a quick question before I start removing the sand from my filter... If the laterals are broken, wouldn't that mean there would be sand spewing into the pool?

I took the top off of the filter and removed the diffuser. So far, nothing seems out of the ordinary...
 
There is a simple solution. You have a multiport valve. Vacuum to waste and send the silt out to sewer or wherever your backwash line goes.
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Well, that's a band-aid but I can't see how it will fix the issue if silt keeps returning to the pool.

If you live in an area of high water costs, vacuuming to waste can get pricey.......especially if you keep having to repeat it.
 
duraleigh said:
There is a simple solution. You have a multiport valve. Vacuum to waste and send the silt out to sewer or wherever your backwash line goes.
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Well, that's a band-aid but I can't see how it will fix the issue if silt keeps returning to the pool.

If you live in an area of high water costs, vacuuming to waste can get pricey.......especially if you keep having to repeat it.
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This is a fair concern as you will lose water. 500-1000 gallons depending on the size of the pool? But as a sand filter owner, the OP should be quite used to losing water to the backwash line due to the frequent needed backwashing of a sand filter. Perhaps infrequent backwashing is the cause of the OPs troubles here as silt may have made its way down through the sand bed and has begun circulating back to the pool. At the end of the day, taking the sand out of the filter and inspecting for broken laterals seems a bit misguided at this point as the OP has not indicated any sand from the filter in the pool and a lateral in itself is hardly capable of filtering silt anyway. The sand should filter the silt, and the laterals just provide a means for water to return to the pool without allowing sand to go with it. If the sand is full of silt then flood it to clean it out or change it and get on a proper backwash schedule going forward. Vac the pool to waste and then get on a frequent vac schedule that coincides with the BW schedule. And of course make sure that the pump is properly sized to the filter.

To the OP: What are the details of the system? Filter size, Pump size and model, how old is the sand, what is your BW schedule, etc?
 

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