How Do I Stop Sand Going Back Into The Pool..Pool Keeps Getting Dirty..


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Have a sand filter. About 4 years old as is pool. Lately I've noticed that after my automatic pool cleaner completely cleans the bottom and the skimmer has cleaned the surface, the next day the pool has dirt in the bottom.

This is without us even using the pool. Seeing a new leaf or bug, or whatever floating in the bottom is normal after the pool sitting overnight, but dirt in the bottom leads me to believe my filter is not working properly.

I backwash/rinse and the problem remains. Is it time to change the sand?

Thanks for the question Rod

This problem faces alot of sand filters. About 95% of the time when dirt/debris returns to the pool it's these:

1. Broken lateral and/or diffuser

2. Channeling

3. New sand

4. Old sand

5. Not doing the RINSE after backwashing

A broken lateral means that the dirt is not being captured in the sand. The dirt returns back to the pool through the returns. For a broken lateral you need to scoop out the sand, replace the lateral, then replace the sand.

It's manual labor, but if you can screw in a light bulb you can replace a lateral. Channeling is when the sand becomes clogged with debris and oil. Water inside the filter finds its way down the sides of the filter and returns as unfiltered water.

An easy way to check this is to unscrew the
top of the filter. Obviously turn off the filter first and release the pressure. Feel around the inside sides of the filter for pits, edges, holes, etc... Squeeze the sand together. If it sticks like sandy Crisco, you have have channeling. You'll need to degrease the filter.

If you do have this problem you can email back and I'll walk you through an easy way to do this. New sand has alot of finer particles that pass through the filter and back into the pool. This will decrease as the sand settles down.

Old sand is when the sand becomes very smooth and smaller. The filtration is not as good and that allow dirt back to the pool. Don't backwash too frequently. You'll waste too much water and a little sand get taken away each time. If you do put new sand in be sure to put the correct number of pounds in and get the correct size sand for your filter.

Also check what's called "freeboard". This is the measurement from the top of the tank to the sand. You can call the sand filter manufacturer and get the correct measurements.

RINSE setting on the Multiport valve after backwashing. Dirt and sand gets trapped in the lines after a backwash. If you don't RINSE afterwards the dirt goes back into the pool. About 30 seconds is all you need.

Hope this helps and have a great swimming season


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Feb 02, 2014
How Big Must Your Filter Be?
by: Jason

Just moved into new house and have a 30000 Litre pool where I keep having dirt on the bottom. I'd vacuum backwash, rinse and the next day still there but only if the motor is running, if off then no debris.

I have had the sand changed in my filter but my filter is only 1 bag filter is this to small for my size pool? I have a 1.1 kW motor so that should be okay but worried about the size of filter?

Then when I plug in a kreepy crawly it doesn't suck yet a manual vacuum works fine?

Need help please?


Jul 10, 2014
Bugs Getting Back In Water
by: Anonymous

What causes bugs to come back in pool through the exchange line.

It could be a variety of issues ranging from too large pump for the filter to torn grids for a DE filter or ripped pleats on a cartridge filter.

For a sand filter it may be broken laterals or channeling. This is when water goes down the sides of the filter and is returned to the pool as dirty unfiltered water.

Without knowing the kind of filtration system you have it's a little more difficult to diagnose but you can start with the above tips.


Aug 24, 2014
New Question-Please help;Dirt, not sand returns to pool
by: Ren

I bought a 30' above ground pool three years ago. It was installed by the company I purchased it from. For three years the dirt & small debris, without sand, returns to the pool after vacuuming. I have placed a panty hose over the return, per advice, while vacuuming to confirm to the company that dirt was returning to the pool. There is no sand in the dirt & small debris. Last year at the beginning of the season I paid the company again to come and fix the problem. They replaced the laterals(I still have the first set as the tech said they were not broken)and they added new sand. The company wants to be paid for each attempt at correcting this ongoing problem.

I have applied multiple types of advice such as, backwash and rinsing every time I vacuum, as sand may be too dirty; not backwashing as sand may be too new (tried for a few weeks at a time). There is not any channeling in the sand. Dirt and small debris start returning before I finish vacuuming. Within 24-48 hrs it is all back in the pool. To get rid of it I must vacuum to waste, which is a waste and expensive.

The consistency of the fresh dirt that falls in the pool will change after it has passed through the filter a number of times. It changes into a fine silt and starts to stick to the bottom of the pool. The pool water is sparkling and clear, the PH is balanced, the floor and the walls are not slimy.

I have been unable to resolve this issue. I am extremely burnt out by the constant need to vacuum, knowing it is all returning back into the pool. Can this happen if there is not enough sand in the filter? (The company said there was enough sand each time they came out)Have you ever heard of dirt and small debris (without sand) returning to the pool? What can I do to fix this?

Thanks for the question Ren

It sounds like you're doing all you can but I just want to summarize some troubleshooting tips. Sand filters are pretty straight forward but I want to give you some more info. I not aware how much you know so I'll start from the beginning.

There are two sides of your pool, the suction and return side. All the dirt comes in the suction side and then is returned.

The issue you're having is with the suction side so anything after the filter (return side) could be a non-issue. I say "could" because you may have a crack in the plumbing of the return side which is allowing dirt to enter the pool through the returns. If it's this you'll need to contact a local leak detection company.

You can go down list list and check off what you may have done and new things to look at:

- Broken laterals
- Correct amount of sand and right kind of sand. Most use #20 silica media. Also check the freeboard. This is the measurement from the top of the sand to the top of the filter. Your owner's manual will have this information or you can contact the manufacturer. Very important but mostly overlooked.
- BACKWASH until the water runs clear and RINSE for 1 minute
- Check the multi-port valve (MPV). The main area that goes first is the spider gasket. This could be worn out or broken which is allowing dirty water into another chamber.

There are only a few place to look, namely, the laterals, standpipe, and MPV.

Check these and see how it turns out.

If you feel your situation is more complex than this, I do phone consultations for a donation of your choice. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation

Hope this helps and have a great rest of the Summer.


Nov 08, 2014
Water coming out of bleeder valve
by: Lynn

I changed the sand and laterals I had sand coming back in pool after someone else had changed the pool sand. After new sand and laterals were installed this time after putting lid back on tr100 triton ii side mount water shoots out of bleeder valve.

The o ring on bleeder valve replaced. Please help me figure out how to get her back operating so I can turn her back on. Thanks Lynn

Jan 18, 2015
Why Is Sand Returning To The Pool
by: Toni

This year we changed our sand in the filter. When we first turned on the pump a small amount of sand returned to the pool. We thought this was normal. After vacuuming the the pool today we backwashed then rinsed and when we turned the pump to filter and restarted the pump an enormous amount of sand returned to the pool.

This lasted for a few minutes. There was so much sand that we turned off the pump and are afraid to restart it. Hope you can help.

Thanks for the question Toni

I have answered this and similar questions on the pool Q&A forum page in the "Sand Filter" category:

Swimming Pool Questions and Answers

Here are the detailed answered questions:

Swimming Pool Sand Going Back Into The Pool

Swimming Pool Sand Filter..Pool Seems To Be Manufacturing Small Debris

Why Is Sand Going Back Into The Pool After Backwashing?

Hope this helps and have a fun and safe swimming season.


Jan 18, 2015
What's This Green Stuff On Top Of The Sand
by: Nadia

I need help. All the dirt is going back in the pool when I pass the vacuum. I changed the sand and the dirt the pool water is still not clean. I do not have any laterals, it is a different thing. I did plug everything o.k. but it's still dirty.

I have green stuff on top of the new sand I put it and green stuff in the pool.

Thanks for the question Nadia

I'd like to have the make and model of your sand filter. This way it would be easier for me to troubleshoot your problem. I know that Media Master Sand Filters by Doughboy have no laterals.

I'd also need a complete list of your chemical readings. Normally green pool water is the result of a lack of chlorine or sanitizer. Thanks once again and hope to hear from you soon.


Jul 22, 2018
Sand entering in the pool
by: Anonymous

I have 15 round pool, and I have sand filter I changed the lateral and sand keep getting there any ideas what I can do ?

If the equipment is in good shape (laterals and standpipe) and it has new sand, you're going to get the smaller particles returning to the pool. This is simply part of adding new sand. It will decrease and eventually stop. In the meantime, you can sweep the sand into one area then vacuum to waste.


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