Why Am I Getting Sand In My Pool

A basic high-rate sand filter is just that basic and the parts that operate it are replaceable and can easily crack or break after hours of usage. There are signals to look out for and one is sand on the floor of your pool which is noticeable sometimes at the return lines which should indicate something broken inside the filter that will answer the question. Why am I getting sand in my pool?

If sand suddenly appears in your pool, piled up in front of the return lines, it’s a sign of a broken component in the filter, the most common being a cracked lateral or standpipe made of plastic located at the bottom of the filter that can be replaced once the sand is removed from the filter.

Sand filters are pressurized filtering systems. The pool water is pumped through certain size sand, which will remove particles bigger than that size as well as leaves, insects, and debris that ends up in the pool. After five to seven years, the sand gradually loses its sharp edges and its ability to filter the water and is lost through the filter system.


Why Is My Pool Filter Blowing Out Sand


Most if not all the pieces in your pool filter are made of plastic. If you see it blowing out into the pool, most likely one of those pieces is cracked or broken. The most common problem is a cracked lateral, which is one of the perforated finger pipes at the bottom inside of the filter that catches water that has circulated through the sand.

Unless your sand is old and has lost its shape and filtering ability which passes through to your pool or you just changed the sand in the vessel and overfilled it, then it’s most likely a:

  • cracked lateral
  • standpipe
  • the seal that is worn or broken (less likely) 

In my 30 years operating an inground pool and helping others with theirs, 99% of the time, one or more finger laterals are located inside at the bottom of the sand filter. This is especially true if you are opening at the beginning of the season after a cold winter. The only way to know for sure is to open it up and inspect the assembly.


Sand filter Laterals


See the source image The laterals are tubes that look like fingers arranged in a wheel-spoke pattern at the bottom of a central pipe. Each lateral has small holes, like a sieve, that allow water to pass through them while keeping the sand particles out.

Depending on the design, size, and model, your pool filter has between eight and ten laterals, and a crack in just one could lead to problems. The laterals are tubes that look like fingers arranged in a wheel-spoke pattern at the bottom of a central pipe. Each lateral has small holes, like a sieve, that allow water to pass through them while keeping the sand particles out.

The tubes or fingers fold up and down so that you can pull the whole assembly out of the filter to flush and inspect the plastic piece looking for cracks that can develop anywhere in the finger or where the finger connects to the standpipe.



How to Replace Laterals in a Sand Filter


Once you decide that there is a problem with the Sand Filter and it’s not the Chemistry of the pool water. Go ahead and:

  • Power down your system
  • Open the main drain plug and drain the vessel
  •  Remove the Multi-Port Valve– loosen the collar- if you have a Top Mount Multi-port and need to cut PVC-leave extra hose

                          Lateral & Stand Pipe
  • Shine a flashlight inside the filter when you pull the Multi-Port Valve, You will find a layer of hair, grease, and God knows what else is there on the top layer of sand. Use a trowel a take off the top layer.
  • Better yet this is the best time to change all the sand


  • Move the Standpipe aside carefully so as not to break it, inspect the lateral fingers so they may not be broken, and inspect the top of the sand and walls of the inside of the vessel.
  •  If you don’t want to replace all the sand just replace what you take out. This should be good enough. When I have done this, the sand underneath is normally clean and good to go. I have gotten a few more years out of my sand by adding a bag of sand and an additive that will help clean the rest. The Sand Cleaner is sold in any pool store. If you decide to empty all (normally the best decision unless you like opening your pool filter) the sand and replace it  with the manufacturers recommended size sand, then:


  • Remove the rest of the sand with the trowel, wet vac, small plastic beach bucket or coffee can until you can get down to the Lateral Assemble
  • Fold the ends of the lateral arms up towards you, like an umbrella, and remove it. Rinse it a couple of times. The arms have small slits that the pool water moves through. Sometimes they will clog up. Inspect the Standpipe. Look for any cracks or breaks in the plastic.
  • Before filling the vessel with new sand cover the top of the standpipe, so no sand falls in. Use a plastic cup or a rag
  • Rinse out the remaining sand through the drain in the filter and you are good to go.
  • Fill the tank with new sand. Use the fill line on the Inside-top of the filter and always check the Plate on the outside that will tell you the exact amount and type of filtering sand to use. Never use anything but what is specified by the manufacturer.
  • Backwash filter until it clears then filter as normal


                        The Inside Parts of a Sand Filter



How Do I Get Sand Out Of My Pool


If you let the sand accumulate for a while then use a long-handle pool brush and sweep the sand up against the wall in a pile and vacuum the pile to waste. You don’t want to add old sand that has been cycling for a long time which will end up on the top layer inside the filter or just get rid of it. If the sand was worn down and made its way through the filtering system then it will do the same thing again.



After five to seven years, the sand gradually loses its sharp edges and its ability to filter the water. When the sand no longer effectively filters the water, you should change it according to the instructions for your brand. Most filters like Hayward recommend 3 to 5  years according to usage.



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JimGalloway Author/Editor



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