How to change the sand in a swimming pool filter?
A question often asked of pool experts is how to change the sand in a swimming pool filter. Over time, the rough silica sand that started off at around .45-.55 millimeters in diameter starts to become smaller and smoother. As it is the roughness of the sand that makes it efficient for filtering out particles of dirt and other debris, it will need to be periodically replaced to maintain filter efficiency.
How Often Should the Sand be Changed?
Although a properly maintained filter may be able to go as long as 20 years most experts agree that every 5-7 years would be ideal. The longer you go before replacing the old sand, the less efficient your filtering system becomes at capturing debris. This can increase the need for additional chemicals to keep the water balanced and shorter cycles between backwashing.
After a period of 5-7 years the sand may be worn enough to allow dirt to penetrate deeper into the filter where the backwash cleaning process will not get it all. If the filter requires frequent backwashing, calcification or “mudballing” may have occurred in the sand bed. Mudballing can happen when the bed is not disturbed enough during the backwash process because of insufficient backwash velocity. Eventually the bed can become coated with an impermeable cement-like mass.
How to Change the Sand?
You will need to open the filter to drain the water and remove the old sand.
Opening the filter:
1.Filter with Multiport Valve Mounted on Top – If your filter has the multiport valve mounted on top, the plumbing pipes running to this valve will need to be removed.
- Removing the plumbing may require cutting the pipes. The cut plumbing can be reconnected with unions or couplings. It is strongly advised that you reconnect the pipes with unions to make future service on your filter much easier.
- If the multiport valve is mounted on the side of the filter, there should be a small top on the filter which can be removed or a tank bolted or clamped in the middle which can be taken apart.
2. Filter with Two-Piece Tank – If the filter consists of a two-piece tank bolted or clamped together in the middle, drain the water before taking the tank apart.
- Pull the drain plug and let the water drain.
- Now you can pull the tank apart.
Removing the old sand:
3. Filter with One-Piece Tank – If the filter is not a two-piece type but has an opening at the top, either through the multiport valve or cover, there are two options for removing the sand.
- If your filter has a larger plug on the bottom with the winterizing plug threaded into it, just open the larger plug to allow the sand to flow out of the tank.
- You can use a hose to wash out the tank.
- If your tank is a single piece without the bottom plug, the sand will have to be dug out from the top (preferably with a plastic cup or scoop – not a metal shovel) being careful not to damage the filter laterals which are located under the sand bed.
- Pull the drain plug to allow the water to drain.
- If the filter has a top-mount multiport valve, a stand pipe will be directly in the center of the opening. Do not attempt to push or pull this pipe out of the way as it is connected to the filter laterals which can be broken.
- Dig out most of the sand with a small plastic cup or scoop.
- Once the laterals have been exposed it is possible to move the stand pipe out of the way.
- If your filter has the side-mount valve, there will be an overdrain (diffuser or distributor which fills the opening on top.
- This overdrain is removable and usually just unscrews.
- The pipe it is connected to can be rotated out of the way.
- In some cases the overdrain may be glued to the pipe so you will have to rotate the pipe with the overdrain connected.
- Proceed with carefully digging out the old sand with a plastic cup or scoop.
4. Inspecting the Filter Laterals – The laterals in a filter allow the pool water to leave the tank and flow back to the pool. This is a good time to inspect the laterals for any cracks and replace them if necessary.
- Most laterals simply unscrew from the tank allowing for easy inspection and cleaning.
- In some two-piece tanks the laterals snap into place, in which case you will be able to remove the entire underdrain unit in one piece.
- Sometimes the laterals may be glued in so do not try to remove them; they break easily.
- If there are any signs of breakage you will need to replace the laterals.
- To remove any impacted dirt, the laterals can be soaked in a mixture of muriatic acid and water then rinsed thoroughly.
- Rinse the tank before reinstalling the clean laterals.
5. Replacing the Sand – Make sure to replace the underdrain assembly first if it was removed.
- Fill the tank half-full of water to provide cushion for the laterals.
- After each bag of sand is added use your hand or small scoop to level out the bed.
- Add the appropriate amount of sand as indicated on the manufacturer’s label. If the label is missing or impossible to read, consult with a swimming pool expert.
- Some labels will require pea gravel, but usually sand can substitute for the gravel without any problems.
- Once the proper amount of sand has been added, the tank and multiport valve (if applicable) will need to be reassembled.
Once you have changed the sand in a swimming pool filter and reassembled the tank, it is important to start the filter system on the backwash setting. Doing this will wash away any dust from the sand and allow it to settle around the filter laterals after backwashing is completed.
1/ shut down the filter/pump. 2/ remove the drain cap on the filter bottom 3/ remove the multiport from the filter top and any associated plumbing. It justs lifts straight up after you’ve removed the collar. 4/ The easiest way to remove the sand is with a wet / dry shop vac. Be careful not to move the central stand pipe, you could break it. Once the sand is out, remove the lateral assembly. It looks like a wagon wheel. The lateral fingers will either fold up ( Hayward filter) or unscrew ( Jacuzzi or Sta Rite). Inspect those parts for damage or wear and replace as needed. 5/ Re install the laterals. Centre them in the tank and put a paper coffee cup over the standpipe hole. This stops sand that you pour in from going down that pipe. You don’t want it in the laterals. Carefully pour in the required amount of new silica sand. I suggest using silica since not only is it readily available and cheaper , it’s also proven. Other alternatives aren’t. Other media types that may possibly be used
