Most manufacturers recommend that you change your filter sand about every 5-7 years. “Why do I need change the sand at all?”, you ask? Well, over time as water rushes through the filter, the jagged edges of the sand which help to trap debris wear down and become smooth. When this happens the sand can no longer trap debris and particles effectively and contaminants can pass through the filter sand and back into your pool.
If your pool water is chemically balanced, the filter system is running the proper length of time (8-12 hours a day) and the bather load is normal, but the water will not clear up even if you use a clarifier, you probably need to change the filter sand.
Another indication that it may be time to change the filter sand is when your filter cycles become very short, and you need to backwash the filter very frequently – more than you had to do in the past.
Filter Sand and Filter Sand Alternatives
Before you start taking apart your filter you will want to make sure you have the new filter sand ready to go. The only sand appropriate for use in pool filters is #20 silica sand, which is .45 -.55mm in size. Do not substitute any other kind of sand; it will not work properly in the filter. Check your specific sand filter’s instructions to determine how much sand is necessary, and don’t add too much or too little filter sand.
If you would like to increase your filter’s cleaning power, consider some sand alternatives, like ZeoSand. ZeoSand is made of a high purity, natural mineral (zeolite) that has a surface area 100 times greater than regular pool filter sand. This allows smaller particles to be trapped, improving water clarity and increasing the time between backwashing. It is added in the same manner as regular filter sand, but you can use about 50% less ZeoSand. If your filter usually requires 300lbs of sand, you can use 150lbs of ZeoSand.
Another filter sand alternative is now available, and it’s called FilterGlass. Made from recycled glass , FilterGlass is an eco-friendly replacement for silica sand and zeolite that removes contaminants as small as 2 microns. (!) That’s equal to a DE filter! And because FilterGlass is lighter than silica sand, you can use 20% less than regular filter sand.
Remove the Old Filter Sand
Before you begin working with the filter you will need to turn your pool pump off and disconnect power to the pump at the circuit breaker. Next you will drain the water from the filter. Remove the drain cap or plug at the bottom of the filter to allow the water to drain out.
After the water is drained you can begin taking apart the filter to remove the old sand. Filters with the multiport valve mounted on top (most residential filters) will require that you disconnect the plumbing running in and out of the valve. If you use PVC and do not have unions on these pipes, you will need to cut the pipe to remove the multiport valve. Choose a location to cut that will allow an inch or two of uncovered pipe on either side, so that you can easily reconnect the pipes with a coupling.
You may wish to consider installing unions when you reconnect the pipes to allow for easier service to the filter sand in the future. Sand filters with the multiport valve mounted to the side will have a dome on top that can be removed to gain access to the sand and will not require you to remove the multiport valve.
After removing the valve, you will notice a center standpipe sticking up inside the tank. Use tape, a cup or some other kind of cover to block the opening of the center pipe to prevent sand from falling down into the pipe as you remove it or add new.
To remove the sand from the filter you can either scoop it out with a plastic cup or use a wet/dry shop vac and suck it out. Once you get a good amount of sand removed you may be tempted to just pick up the filter and dump out the rest, but do NOT do this! There are plastic laterals at the bottom of the tank (pictured above) which could break very easily under the pressure of the sand falling out.
As you get close to the laterals, use care to avoid bumping and possibly cracking the laterals in the tank bottom. After years of chemicals and high rate water flow, they are probably brittle and could break easily.
Clean and Inspect the Filter tank and Internals
Once you have all the old sand removed you will need to clean the filter tank and inspect for any damage. Run a garden hose in the tank and wash the inside thoroughly.
Inspect each of the laterals closely for any cracks and replace them if necessary. If your laterals are quite old, you may consider replacing the entire set at the same time as you change the filter sand. You don’t want to repeat this entire process to replace the laterals tomorrow, or next year.
You can find the correct laterals for your sand filter tank in our filter parts department. After inspecting the internal standpipe and laterals, replace the drain cap/plug that was removed earlier at the bottom of the tank. Then add water to the tank, deep enough to cover the laterals – to provide a cushion when adding the new filter sand.
Add New Filter Sand or Sand Alternative
After adding water to the tank you can start pouring in the new filter sand. Be sure that whatever you used before to cover the center pipe is still in place so you don’t pour the new filter sand into the center pipe as you add it to the filter tank.
If you have chosen to use a filter sand alternative thoroughly read any instructions to make sure you do not skip any necessary steps for that particular product. Gently scoop the sand (or whatever sand alternative you have chosen) into the tank, or you can set the bag up on top of the tank and slice open the bottom with a razor knife.
Be sure to keep the center pipe straight and firmly sitting on the tank’s bottom throughout this process. If it ends up crooked or too high, you won’t be able to properly re-install the multiport valve and will have to remove the sand to realign the standpipe.
If adding regular filter sand, wear an appropriate dust mask. Silica dust can be hazardous, so take care not to breathe in the sand dust while adding it to the filter tank.
Once you have added the amount of filter sand recommended by the filter manufacturer, remove the tape or whatever covering you used on the center pipe and re-install the multiport valve. Reconnect the plumbing to the multiport valve. It is a good idea to backwash the filter for a few minutes to remove the sand dust before you begin normal filtering.
When you are ready, turn the pump off again and change the multiport valve setting to “filter” and turn the pool pump back on. Note the reading on the pressure gauge; this is the clean sand filter pressure that you want to maintain. Any time you see the pressure 8-10psi over this reading you will want to backwash to clean the filter sand.
While it may seem like a lengthy process, most people seem to be able to change their filter sand in just a few hours. As with most tasks, the first time may take you a bit longer, but you’ll know what to expect in the future.
If you have any questions before or during the filter sand change process please give us a call at 1-800-288-7946, we are always happy to help!
InTheSwim Staff Blogger