The Sandbar is open!
If you’re reading this then there may be a sand berm big enough to threaten shipping lines at the bottom of your pool. Ok, maybe that was a little dramatic, but a dusting of sand around a return line can cause a panic in any pool owner’s mind. Sadly, this is an all too common problem with sand filters but luckily there are some usual culprits that are easy fixes.
Cracked Lateral
If you ask a pool tech about a sandy pool bottom, his first question to you will be, “Did you check for a cracked lateral?” There is a good chance you did not and there are two main reasons why. First, laterals are a pain in the neck to get to, and second most homeowners don’t even know what they are.
Located at the bottom of your filter, this array of 6 – 8 perforated tubes are the last line of defense keeping sand from pouring into your pool. In a sand filter tank, water pours into the sand from the top where it filters its way down through the couple hundred pounds of sand to the bottom of your filter. This is where the little laterals come in. The now filtered water is collected by the laterals and is rushed through the center pipe and and back to the pool. The perforated holes are just big enough to allow water but prevent sand from seeping through.
If there is a crack in one of these laterals sand will find the gap and shoot happily to your pool, to ruin your day. Or at least that’s what it will feel like when you see it pouring into your pool.
The hard part is figuring out it was the laterals, the easy part is actually fixing the problem. For step by step by step instruction, review our guide How To Replace a Lateral in a Pool Sand Filter.
Did You Know?
Sand will leave a telltale streak pattern on the pool floor around the return line. If your pool has a wide dispersal of sand then it may be getting in your pool from an outside source.
Spider Gasket
A multiport valve is like a highway interchange for your water as it routes and diverts the flow to achieve your desired setting. If water is flowing from the waste line when it is not supposed to be then the spider gasket has likely gone bad. Shaped like a wagon wheel, this gasket seals the diverter to the base of the valve preventing leaks into unselected portholes. If the water is allowed to leak into unintended ports then it may accidentally backwash debris and sand into your return.
The spider gasket wears out depending on use and water chemistry. Hard water is hard on rubber. Also, always turn your multiport’s selector handle in the same direction, whether it is clockwise or counterclockwise. If the handle is turned both ways it is more likely to warp the gasket or unseat it from its groove.
For step by step by step instructions, review our guide How To Replace a Spider Gasket on a Multiport Valve.
Don’t Be Dense, Please Rinse.
Would you take a shower by soaping up, then lathering your hair with shampoo just to turn off the water and walk out before rinsing it off? No, I did not think so. The same principle goes for washing out your sand filter. When a filter is backwashed, it is an absolute must that it be rinsed before returning to normal filtering mode.
During backwashing the water’s normal flow is reversed to flush out or loosen heavy dirt particles that clog the filter. Once the backwash is done those particles are deposited in the lines of the filter for the Rinse. If the rinse step is skipped after the backwash all that dirt and nasty stuff goes right back into your pool. Don’t be dense, please rinse.
Can’t Teach Old Sand New Tricks
If you take sand down to its singular property, it is just tiny grains of sediment and when enough is clumped together, it makes one heck of a filtering media. The bad thing is that, just like the three month old milk in the fridge, it has an expiration date. Sand can last approximately 3-5 years in a filter before it needs to be changed. A sign of sand turning is usually high pressure that does not subside even after a repeated backwashes. A signifier that goes along with that symptom is fine sand at the bottom of the pool.
Like water does to large rocks in a river, it smooths and wears down the size of the sand granules. Eventually this wearing gets the sand down to a size where it small enough to fit through the perforated holes in the laterals. Next stop is the bottom of your pool. If your sand has been filtering for a few years and there is returning sand to your pool in congruence with high pressure, this may be the cause.
As usual our pool techs have a guide covering the steps to replacing your sand. If there are some steps you’re fuzzy on, check our How To Change Sand In a Sand Filter guide.
My pool is in ground. The filter is sand with glass media. It is salt water.
I am seeing fine, bright white sand-like deposits on the bottom of the pool. That material is very hard. Any thoughts on this?
Is it hard like glass? If so, you have glass media leaking into the pool through the laterals or somewhere just like sand would.
I keep finding sand in the bottom of my above ground pool. I dont use sand in my filter I use glass. It leaves me to believe I have a hole on the bottom in my liner, but, my water level never drops! Can I have a hole and not lose water? Has anyone ever experienced this? Thanks
You would definitely see water loss. The wind could bring in the sand. Or, it would help if you used a clarifier to allow the filter to catch the smaller particles.
My New multiport valve Is losing water at the waste port when it is set at filter. I just changed the spider gasket and it is still leaking. Is it possible that it is not seated right inside the valve? Is there a way to tighten it so it doesn’t allow water to bypass it?
I am getting sand out my returns. Above ground 24’ pool. System is only on 2nd season. Before the season I installed a heater, ball valve bypass, and hard plumbed the entire system with 1 1/2” pvc eliminating the 1 1/4 flex hoses. Now I seem to be getting sand out the returns. I replaced the laterals and standpipe which looked fine, installed new ruby sand making sure to add proper amount and cushion, pretreated and backwashed per Zeo instructions. There seems to be more sand coming out when I use the bypass then when i circulate thru the heater. There is also a noticeable sound difference.
Pentair Sand Dollar SD 60 with 1.5hp motor/pump assembly. Could the pipe size change be causing this or could it be possible I have a damaged spider gasket.
Hello
I have a question, besides being a bit annoying, if the pool is vacuumed regularly to get rid of the sand, can it cause any other issues in the system?
The sand itself is not harmful to the equipment but it is a sign that something within the system is not right.
I have just installed a second-hand cristalflo T-240BP-1 sand filter and replaced all valve gaskets and handle spring and installed a new filter laterals/pipe assy. I have a 1hp pump connected. Every time I turn off and on again the pump, even after having run it for more than one day, some sand comes out in the pool for approx 1 minute and it is not fine sand. I hear some turbulence of air, water and sand in the filter for a couple of minutes when I switch it on, but in theory that water should pass through the laterals and have no sand reaching the pool. I inspected the valve body too and it does not show any cracks. The spider gasket is also sealing ok- there is no water leaking in the other channels. What could be the reason for the sand?
The sounds you are hearing are the unit purging air from the system or just the natural churning of the pump filling the filter.
As for the second-hand filter, there could be a cracked lateral or a hairline crack on the standpipe. have you checked that?
We have sand in our pool. Just purchased a new filter and decided to go with Filtraballs. Vac on waste to remove sand and still have some dispersed lines of sand in the pool.
Any suggestions?
Use a clarifier or a flocculant to make quicker work of clearing the sand if regular vacuuming is not working.
Hi Matthew.
I have been getting deposits of sand across the bottom of my pool and not just at specific channels/positions in the pool. Would this indicate external sand being blown into the pool or is it a symptom of leaking out of the sand filter ?
Is it true that sand that hasn’t been refreshed for sometime can become rounded and smooth making it able to pass through the filter lateral system and into the pool ?
I have 2 month old pool with Hyawred sand filter I see some sand in Auto cleaner and some in bottom of the pool not much. Water very clearer, the pool guy said some of the fine sand can make it way to the pool?! Always I rinse after backwash
We’ve been trying to restore our above ground pool that had been unused (swimming) or little to no chemicals added for an extended time. This year we Rolled up the sleeves and drained the dark green algae filled pool. Had a large amount of leaves to remove (they stained the pool in some areas. We took soap and water and scrubbed the remaining algae and scum from the sides and bottom the best we could. Emptied the sand filter which was something I hope to never have to deal with again (2 year old sand but dark color and green). Cleaned the inside of the filter surface but putting water in it, then just a small about of shock. Drained that water flushed the tank and back down the PVC pipe back through the laterals. Everything cleaned and no visible cracks in the laterals… tried to remove one but no deal scared I’d break it. Fill the filter with water about 4” over the laterals, and yes, I still have my original cap that closes the PVC pipe while adding sand. Went to a local pool supply store and purchased 150 lbs of sand. Slowly poured the 150 lbs of sand in the filter. Using the jet setting on my hose to put water in the filter spreading the sand to the sides between adding each bag. Once sand was in, I filled the filter with water (maybe some spilled over in the PCV pipe). Put the head back on and open the valve to backwash. I did not do the rinse. Turned everything on and all looked great. Water is crystal clear. I don’t see sand on the bottom of the pool or coming out of the jet. I put a strainer sock over the strainer and it is catching everything. It looks as if it has fine sand particles in it. I try IFR to feel it but whatever this is, it rolls up like lint. I took a roll of it and let it dry for a day on some bricks. It didn’t turn to a grainy sand feel, but rather stayed like a lint ball. Is this sand or something else you’ve heard of? I’ve heard maybe dead algae or pollen?? I clean the sock but see it return, maybe not quite as bad but still visible. Any ideas and reading all these post about sand in the pool, I’m I wrong to assume it’s okay to continue letting the kids use the pool with small sand particles floating around and/or whatever this “lint/sand” looking stuff is in the strainer sock is. Heck with the entire pool sand bag covered in silica warnings (which I’m not sure what that does in the makeup of pool sand) I’m curious if I should go cartridge filter.
Also cartridge filter NOT sand.
Forgot to add this is a saltwater in ground pool. Thanks Debby
Hello Mathew, new pool everything coated in sand can’t power wash off. Goggles left in pool covered with sand or salt grit which sticks to everything! HELP they are coming next week to resurface but that will not fix problem. They have already installed new pump as it went out within two weeks. HELP! Debby
Debby, there is a whole list of things I mention to check in the article. First question, did you check those things?
After opening our in ground pool this year I noticed when I hooked up the vacuum sand would come out from the returns. When we unhook the vacuum, it doesn’t seem to noticeably blow out. We have backwashes and rinsed. Could it be a cracked lateral? We inherited the pool when we bought the house last summer so I’m not sure how old the sand is either. Our water isnt cloudy but here is sand all over the bottom. Not sure if I should try to replace the sand and check the laterals?
If sand is only visible after you start vacuuming; I would presume the problem is not the laterals but old sand. When sand gets gunky, it begins to clump together, which can create channels through which fine silt can slip past the filter media, penetrate the laterals and back to the pool. There is a point where not even backwashing can clean the sand adequately enough. Before switching out the sand, you can try different sand filter cleaners which try to degunk the sand. If those chemicals don’t work, then you need to change the sand.
Hi Matthew.
I have been getting deposits of sand across the bottom of my pool and not just at specific channels/positions in the pool. Would this indicate external sand being blown into the pool or is it a symptom of leaking out of the sand filter ?
Is it true that sand that hasn’t been refreshed for sometime can become rounded and smooth making it able to pass through the filter lateral system and into the pool ?
So I have very fine sand in the bottom of my vinyl lined inground pool but have a cartridge filter. Have a bad feeling that I have a leaking return line. Any thoughts?
Have you tried a clarifier, then vacuuming it to see if any sand returns?