When you backwash or rinse your pool and find sand flowing out of the backwash hose or outlet, your sand filter may have an internal issue.
Since the water flow is reversed during the backwashing cycle, the sand gets a little stirred up; therefore, I suggest postponing switching back to filter mode from the rinse cycle for at least 60 seconds to give the water and sand time to settle.
Why Does Sand Come Out When Backwashing the Pool?
Let’s start by discussing what is and is not typical. When backwashing, rinsing or filtering a sand filter for the first time or after renewing the sand, a small amount of sand may indeed come out. However, it ought to disappear after a few runs. When filling, extra sand frequently finds its way into the wrong areas and leaks into the pool or the backwash hose.
Something is wrong if sand is leaking out. Generally speaking, your sand filter shouldn’t be losing sand. In addition, no sand should be released during backwashing, rinsing, or filtering.
The sand in the filter shouldn’t need to be replenished either. If you need to top off the sand, it means there is an issue, and sand is leaking out.
There are various causes for this. On the list, the first item is:
1) A Standpipe Or Lateral Crack
Sand will leak out during backwash, filtering, or rinsing if a standpipe or laterals are damaged.
To transport water in and out of the sand tank, a thick plastic pipe called a standpipe must pass through the center of the tank. The valve at the top of the vessel and laterals at the feet of the sand tank are both connected to the standpipe.
When backwashing, rinsing, or filtering, if the standpipe isn’t installed correctly or has a crack, and may pass through it and end up back in the pool.
The sand tank’s bottom has pipes called the laterals that are part of the sand filter system. These laterals are constructed with minute pores or openings that permit filtered water to enter the pool while being sufficiently small to prevent sand from flowing through. In a sand filter, there are typically 8–10 laterals.
Water from the pool pump is pumped into the sand container from the top when you turn the multiport valve on the filter in the pool. Filtered material gets captured in the sand particles as the water descends and is filtered away.
However, if one or more laterals are damaged or worn out through aging and deterioration, sand can enter the pool again through the damaged lateral(s).
Start by examining the pool’s bottom for sand around the return jets to determine if that is the issue. The standpipe or laterals are probably broken if sand is close to the jets.
The pool’s machinery must then be turned off. Drain the sand filter, open it up, and check the standpipe and laterals after that. To do this, you must remove the sand. This is when a shop vac comes in handy.
In the middle of the sand tank, the standpipe ought to be fixed. The sand leak will occur if it is not in the center or fractured. A relatively minor crack can already result in a problem. Examine the laterals for damage or cracks in the same way.
How To Fix
It is necessary to replace the standpipe and laterals if they are damaged. The laterals and standpipe should be replaced simultaneously.
Turn the pool pump off, and the sand tank’s water should be drained after obtaining the proper replacement parts. The sand tank’s lid needs to be opened, and the sand should be dumped inside.
The replacements can now be installed after removing the laterals and standpipe. Make sure they are in the right place.
After putting these components in place, add sand to the tank and firmly shut the lid. When filling the standpipe with sand, it’s best to place a rag on top to prevent sand from entering the standpipe. If you accidentally fill it with sand, the sand will return to the pool.
Start the filtering system now. When you initially turn on the pump, you can see a tiny bit of sand. You shouldn’t frequently see sand being added to the pool.
2) There Is Excessive Sand In The Filter
Sand entering the pool during backwashing, rinsing, or filtering is another issue caused by having too much sand in your sand filter.
Sand is stirred up and raised during backwashing. This means that when there is too much sand in the tank, the extra sand at the top will be ejected. Your backwash and rinse cycles will become inefficient as a result of this.
Turn off the pool’s machinery, drain the water, and open the sand filter to see if this is the cause of the sand coming out of it. Check the sand level in the sand tank right now. The recommended level of sand must be determined by consulting the manufacturer’s instructions. Take some of the sand away if it is too high.
How To Fix
The good news in this situation is that the sand filter system will occasionally adjust itself when there is too much sand in the filter system. The extra sand on top of the filter can be drained until it is at the proper level when you rinse or backwash the pool’s multiport valve. This will automatically make the problem right.
You can also accomplish this manually by initially shutting off the pool pump. Next, let some sand out of the tank by opening the lid.
The distance between the sand filter cover and the top of the sand in the tank should always be at least 6 inches.
3) A Faulty Multiport Valve Or Spider Gasket
Sand may flow out of the backwash outlet or the pool’s return jets for another reason, such as a cracked or malfunctioning spider gasket or multiport valve.
Your multiport valve is made up of various chambers that determine the water flow’s direction. The spider or spoke gasket divides these chambers.
The spider gasket shuts the other chambers to ensure that the water is directed through the appropriate section only when the multiport valve is in the filter position or any different stance, for that matter. The spider gasket blocks the other chambers when the multiport valve is set to backwash, allowing water to only flow through the backwash exhaust or hose.
When you switch between filter and backwash, water will leak into the other chambers if the multiport valve or spider gasket is harmed or misaligned. Due to this, the sand in the tank may leak into the pool or emerge through the backwash hose.
You must take the multiport valve apart and examine it to determine if it is the issue’s root. Make sure the spring is tensioned, the valve is free of cracks, and the spider gasket is sitting straight. Additionally, look for any valve cracks.
How To Fix
The spider gasket, multiport valve, or both will need to be replaced to fix this. A replacement multiport valve will need to be purchased if the entire multiport housing is compromised.
4) Huge Pool Pump
The pool pump is large, which is another reason you can notice sand backwashing your pool. Water will be poured into the sand tank at a rate that is greater than the maximum rate of flow of the filter system if the pool pump is too solid or significant for the sand filter.
Due to the enormous pool pump’s higher water pressure, sand particles may be forced into places they shouldn’t be and escape via the backwash hose or outlet.
Check the user manual or the filter’s instructions and look for the maximum current to see whether you have the correct size pool pump. Refer to that and the flow rate of your pool pump.
Your pump’s flow rate needs to be equal to the sand filter’s specified range flow rates.
5) Sand Is Too Small
If the sand tank’s grain size is too small and may leak through the laterals and into the pool or come loose from the backwash hose during backwashing or rinsing.
The only sand that should be used to fill a sand filter is pool sand because it is graded and the correct size. Use only items designed to be used with sand filters.
Sand should have a diameter of 0.45 to 0.55 mm when used in a pool sand filter. This is the necessary size to offer a good filter and prevent slippage through the laterals.
In general, the filter is malfunctioning if there is sand in the pool or if sand is seen flowing out of the backwash hose while the filter is running.
Most of the time, one of the causes mentioned above is the offender. Examine each one and make the necessary repairs based on the instructions. Additionally, for a clean pool, be sure you adhere to the backwashing procedures.
That’s all there is to it. If you enjoyed this topic, read other pool-related posts on this website.