Filters : Sand
Sand Filters
- The sand filter tank is round or egg shaped. The sand contained in the filter strains the impurities from the water as the water passes through the sand. The sand filter uses a multiport valve to direct the water through the filter or out to backwash. The valves are either top or side mount. Both valves work the same way. In filter position, the water is directed over the top of the sand bed and, as the water flows down through the sand, the sharp edges of the sand catch the particles in the water. The clean water is pushed out of the filter through the bottom lateral assembly. The laterals are in the shape of a wagon wheel, with tiny holes along the top edge, to allow the clean water back to the pool and the sand and dirt to stay in the filter.
Why is the filter continuing to run at high pressure even after backwashing?
- Make sure you are following the instructions in your Hayward owner’s manual. The sand bed may be clogged with mineral deposits or other material that will not backwash away. Some calcium based chlorines and other alternative sanitizers could cause a build-up in your sand bed. You may need to change the sand.
- Before you change the sand in you filter, try removing approximately 1” of the top layer of sand, and replace with the exact amount of sand removed. This sometimes rids the sand bed of the deposits clogging the filter.
- You may have to clean you filter system with a special filter cleaner, check with your Authorized Hayward dealer for proper procedures.
- Check to see if there is a closed or partially closed valve on the return piping.
- Your pump may be too small to provide sufficient flow for proper backwashing. Your filter will filter properly, but if your pump does not supply at least 60% of the filter’s designed flow rate, you filter will never backwash completely. Refer to the label on you filter for flow rate requirements. It may be necessary to upgrade the pump or downgrade the filter.
- Your pump may also be exceeding the maximum allowed flow rate of you filter causing excessive backpressure. Check you Hayward filter owners guide or the operations label on you filter for the maximum allowed flow rate. You may have to downsize the impeller or pump to a lower horsepower or change the filter for one that will accommodate the pump’s flow rate. If allowed to continue, a pump that exceeds the recommended flow rate of a sand filter could cause the sand bed to channel (small channels in the sand that allow debris to pass unfiltered). This would cause debris to by-pass the filter.
Why is the filter short cycling (builds pressure quickly after backwashing)?
- Refer to Hayward’s owners guide for proper backwashing procedures. It may be that you are not backwashing long enough. Always backwash until the water is clear in the multiport valve sight glass.
- You may have live algae causing the filter to clog. You may also have mineral deposits building in the sand bed.
- It is highly recommended that you have your water tested at your local Hayward dealer. Compare those results with your own. You may need to update your test kit or replace the testing solutions.
Why is there sand at the bottom of my pool?
- The sand you are using could be too small. Sand that is too small can travel through the laterals in the bottom of your filter and back to the pool. #20 silica sand, .45-.55mm in size, is required. This can be obtained at your local Hayward dealer.
- Prior to adding sand, remember to always remove a lateral (it unthreads) from the lateral assembly at the bottom of the filter. Try putting some of the sand you are going to add inside the lateral. Other than debris sand (fines), 99% of the sand should stay inside the lateral. If most of the sand comes through the holes of the lateral, the sand is too small.Your pump may be too large or the sand level too high in the filter. When the filter is backwashing the water flow can cause the sand to rise high enough and overflow into the standpipe, which will allow the sand back into the pool. Refer to the Hayward owners guide or the filter label for the correct amount of sand for your filter.
Why is dirt/sand passing through my sand filter?
- A lateral could be cracked or broken, the multiport valve may need servicing, or air may be passing through the filter, causing a channeling effect, which permits dirt to get by the filter.
- There may be a broken or cracked lateral located on the manifold of your filter. You will need to inspect these laterals and replace them if necessary.
When do I need to replace my sand?
- On average, sand should be replaced every 3-5 years. This may be longer if the pool stays clear, or shorter, if the filter runs all the time. The jagged edges of the sand wear down and become smooth as the sand ages. When this happens the sand can no longer trap debris particles and dirt can pass through the sand and back into the pool.
- If the pool is chemically balanced, the system is running the proper length of time and the bather load is normal, but the water will not clear, even using a flocculant or clarifier, then the sand needs changing.
- As the sand ages, it may start to clump and the water flow can form channels in the sand, allowing the debris to pass through. Channeling is often seen when the pump horsepower is too large and wants to move too much water through the filter.
How do I change the sand in my filter?
- For our top mount filter, you must first disconnect the pipes leading into the valve and open the drain plug on the filter. Next, remove the clamp holding the multiport valve to the tank body. Once the valve has been removed, you will be able to see the sand bed. The best way to remove the sand is to either use a portable wet/dry vacuum or just scoop it out with a small can. Once the old sand has been removed, hose out the inside of the tank to clean the filter out. Once this water is drained, replace the drain cap and fill the tank 2/3 full of water. This is to protect the lateral assembly while the new sand is added. Add the sand slowly till the laterals are fully covered, then just pour in the remaining sand. DO NOT get sand in the vertical pipe sticking up from the bottom of the filter tank. The standpipe may be covered with a paper cup to prevent sand going into the pipe.
- For a side mount tank, rotate the multi-port valve to the closed position and open the filter’s drain plug. Remove the tank closure dome and expose the top diffuser. The top diffuser lifts off and the old sand can be removed. The best way to remove the sand is to either use a portable wet/dry vacuum or just scoop it out with a small can. Once the old sand has been removed, hose out the inside of the tank to clean the filter out. Once this water is drained, replace the drain cap and fill the tank 2/3 full of water. This is to protect the lateral assembly while the new sand is added. Add the sand slowly till the laterals are fully covered, then just pour in the remaining sand. DO NOT get sand in the internal piping.
How do I backwash my filter?
- When the filter pressure rise 8-10 PSI over the clean starting pressure it is time to backwash. Turn the pump off and rotate the multiport valve to backwash. Turn on the pump and the dirty water will flow out the waste line. Once the water runs clear in the valve’s sight glass, turn off the pump. Rotate the valve to rinse. Turn on the pump for 20-30 seconds. This will clean out the plumbing lines and reset the sand bed. Turn off the pump, rotate the valve to filter position and begin to filter. Take a reading of this new clean starting pressure, so you have a reference point for the next backwash cycle. Water may need to be added to the pool to replace the backwashed water.