Your swimming pool filter is one half of the most important equipment needed to keep your water looking fresh and clean. The filter must be maintained in top condition to ensure sparkling pool water. Pool filter problems, just like the pool pump, must be addressed quickly to stop algae growth.
Today we look at some common Sand Pool Filter Problems to watch for, and how to fix your own sand filter trouble, with just basic hand tools, and in some cases a few sand filter parts.
1. WATER LEAKING OUT OF WASTE LINE
A filter’s Multiport Valve is a complex piece of the filter so keeping an eye on it throughout the season is to your advantage. A multiport valve has more than 12 parts, as well as multiple ports that allow the water to flow. Push-pull valves, mounted on the side of a sand filter, are simpler, with just two ports for filtering or backwashing.
It is common to see a small stream of water continue to flow from the backwash line after you have finished backwashing. Jiggle the handle, and if there’s still water coming out minutes later that signifies a problem with the valve. Most often, leaks like this occur due to a bad spider gasket or plunger o rings on a push-pull. The spider gasket seals the ports, including the waste water port, to regulate the flow of your pool water.
The gasket rubber will eventually wear out and allow water and debris to bypass the intended direction. It is possible to break the seal by turning the valve when the filter’s running. It is important to note that sometimes, the gasket needs only be cleaned up and reset.
To check or repair a leaky multiport valve, shut off power and let the pressure escape. Next, remove the screws from the top. You can now remove the cover, handle, and key stem in one piece. This is known as the key stem assembly. You will find the spider gasket within the valve’s body. You can clean it out and look for signs of damage such as twisting or tears. You can replace it by removing the old gasket using a small, pointed screwdriver and then glueing the replacement spider gasket (flat or ridged).
The spider gasket on some valves like the Hayward SP714T is glued into its bottom, not the inside grooves of a valve body. The most likely reason for the backwash line to leak is a broken spring on the diverter stem or debris stuck within the valve.
2. DIRT COMING BACK INTO THE POOL
Sand filters can pass some small debris back into the pool, and it can be considered normal, especially if you are vacuuming fine, silty dirt. You might see the stream of dirt coming back through the return lines after vacuuming or backwashing. Vacuuming waste will resolve the problem. Rinse after washing will solve the latter.
There are other ways to improve the effectiveness of sand filters, such as using a Pool Clarifier to improve water clarity with a sand filter, and using a Sand Filter Cleaner regularly to refresh the sand and remove oils and scale (and clarifier!). You attach the slime bag to your return line fitting. It acts as a secondary filter and traps very small particles.
- Worn-Out Sand. The sharp edges of sand become less durable over time.
- Calcified sand. Filter sand can be transformed into a sandstone by adding very hard water minerals.
- Mudballing. Oils can collect in a tank and make gooey gunk in the top three-quarters of the sand.
- Channelling. The pump can push water through the filter unfiltered if it is too powerful.
- Bypassing. This could happen due to a too strong pump, a bad spider gasket, or faulty valve spring.
3. BROKEN MULTIPORT HANDLE
Using too much force, or large tree branches can break the handle on top of a multiport valve. You may need to replace the spring in the key stem assembly if the handle is very flexible or floppy. In this case, it may be better to replace the key assembly; it’s definitely a lot easier.
To replace only the handle, simply remove the key stem as described above and place it on a hard surface. Press the top cover to compress the spring. Then, tap out the pin that runs through it and apply pressure to it. After removing the handle, inspect the large nylon washers located underneath it in the middle of top cover. This can cause damage to the handle and disrupt its function. You will also find o-rings at the stem. You can clean and/or replace any valve components, then you can put it back together. Be sure to place the lid in the exact same direction as the diverter so everything lines up properly.
4. LEAKY FILTER TANK
This one’s even easier…it is not safe to repair a cracked tank. You need to purchase a new one, and it’s usually cheaper to buy an entire new filter than to just buy the tank. It is impossible to repair a pressure tank such as a sandfilter. A rupture could cause damage or drain the pool. However, there are other leaks in sand filters that can be repaired with the correct filter parts.
- Leaking air bleeder. These can be sealed with an o-ring, or Teflon tape.
- Leaking drain assembly. A drain plug or cap may lose its o-ring/gasket.
- Leaking flange assembly. Top mount valves seal the tank with an O-ring and tight clamp.
- Leaking bulkheads. Side mount valves have bulkheads mounted on the tank, with lots of spacers.
- Leaks where the pipes connect into valve. Cracks can result from tight fittings.
SAND IN THE POOL
Broken Laterals? Broken Laterals: Laterals are small plastic parts located at the bottom and sides of the sand filters. Their slits keep out sand grains from entering the pool until it cracks. You could also have a cracked standpipe or diffuser. Any internal part that cracks can let sand in the pool.
After backwashing, you may notice a small cloud of dusty sand. However, if the lateral bursts, it will be obvious. Below the returns, you will find several handfuls or more of sand.
What’s the solution? The solution? Drain the tank and scoop out all the sand. You can reuse the filter sand if it’s still in good shape. Pool filter sand usually lasts for about 5 to 7 years.
5. HIGH FILTER PRESSURE
A sand filter needs backwashing when the pressure gauge reads 8-10 lbs higher than the pressure after cleaning. The name comes from the fact that water flows backwards through the filter tanks when you backwash. For 3-5 minutes, backwashing flushes the dirt from the sandbed and the waste line.
“Normal” sand filter pressure? Normal sand filter pressure is around 10 psi. However, it all depends on the size of your pump, pipe, and the resistance from any other equipment. Each pool has a different system pressure gauge reading, so a typical filter pressure could range from 5-25 PSI. “High” filter pressure is anything above 30 psi.
The rule of thumb is that if pressure is higher than normal it’s a dirty filter, and if it’s lower than normal, it’s a dirty pump basket (or impeller). What happens if the pressure gauge is still high after you have washed the filter? Here’s some things to check.
- Bad Sand, or oily, gunky sand. Use sand filter cleaner to clean the sand.
- Bad gauge. Do you see it go to zero after the pump is turned off? It could be stuck.
- Obstruction after the filter. Partially closed valves, clogged or plugged lines.
- Obstruction before the filter. Poor water flow to the filter
- Multiport valve recirculating water, reducing backwash water flow.
Sand pool filter repairs are Urgent, you’ve got to get the water filtering again fast. If you can’t filter the water while awaiting sand filter parts, you may be able to at least circulate the water, by using the filter bypass setting, Recirculate. You can maintain a high level of chlorine by using granular pool shock. Also, brush the pool every day until the filter is repaired.
Give us a call if you want to discuss your sand filter problems – ask for me, or any of the other ITS Pool Experts!
