Filter Problems

  • Last Post 05 September 2022
jkugler76 posted this 31 May 2022

Hello.  I'm looking to diagnose an issue with my filter.  I have a sand filter with a multi-port valve.  This is only the second season using this filter.  The initial problem started when water was leaking out of the waste port while the valve was on the filter setting.  There was a steady stream of water coming out.  Normal operating pressure is 10 PSI, but it would dip to 8 or 9 while water was leaking out of the waste port.  I opened the valve cover to inspect the spider gasket and everything looked fine.  No issue with the spider gasket.  The standpipe looked fine as well.  I have an identical spare valve purchased the previous year, which has never been used.  I swapped it out with the existing valve and same problem occurred.  I backwashed the filter a few times.  After each backwash, the PSI went back to 10 and the water leak out of the waste port stopped temporarily, only to start leaking again about an hour later.  I've been dealing with this for two days now.  Today, I left the filter on and went out for a few hours.  When I came home, sand was coming back into the pool from the return.  PSI is now at 0.  I had to shut the filter off to stop sand from entering the pool.  Now, I'm at a loss.  Could the issue be isolated to one main problem or multiple problems.  Any ideas would be greatly appreciated.

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JCMC70 posted this 01 June 2022


You have certainly presented a head scratcher. What you are describing, water coming out the waste line, sand going into the pool and filter pressure problems could be caused by a spider gasket that is worn or improperly seated in one or more areas of the gasket. But given that the filter is only 2 years old and that you have changed the multiport valve to a new one, it's very unlikely that both multiport valves are bad.

As for sand getting back in the pool, if it isn't the spider gasket or multiport valve there is one thing you can check before you go digging in the sand. Most new filters have a vent tube inside the tank. This is a small diameter tube that is attached to the laterals hub at the bottom of the standpipe. It extends above the sand bed into the top of the tank. There is a fine mesh screen at the top of the tube. If it has been damaged or has become dislodged sand could enter the tube and get returned to the pool. You can check this by removing the multiport valve and looking for this tube. If there is a vent tube and the screen is undamagd and in place or if there isn't a vent tube you will need to check the standpipe, laterals hub and laterals. For this you will need to drain the filter and remove all of the sand. Once the sand has been removed, if there was a vent pipe, make sure it is securely attached to the laterals hub. If it has come loose attach it securely, if there wasn't a vent tube you will need to remove all of the laterals (most laterals just screw on) and then pull the standpipe and laterals hub out of the tank. Check for any hairline cracks or breaks. Those are the only things I know of that would cause sand to be returned to the pool.

As for the filter pressure issue, pressure is dependent on the volume of water entering the filter and whether or not the system is sealed. We know there is water leaking into the waste line. That affects the filter pressure. A faulty spider gasket or multiport valve that could allow part of the water entering the filter to go to the "Recirculate " section of the valve would bypass the filter thus reducing the pressure. A partially obstructed or partially crushed suction line could reduce the volume of water going to the filter. And finally, a undersized pump or oversized filter would affect the pressure in the filter.

Hope this helps in some way.



DanLamas78 posted this 05 September 2022

It seems that the problem is related to the valve itself. In the initial stage, the leak was coming out of the waste port. The valve was closing fine in this setting and not leaking. But, it seems that the seal of the valve must have worn off. So, the water is leaking out of the valve body itself. This is usually what happens at the end of the valve’s life cycle. I think the only thing you can do is to replace the valve. As for the sand, I suggest you get a small excavator and dig a hole beside the pool. Connect the hole to the current valve opening (make sure the valve is turned off) and the sand will go into the hole and you’re good to go.