Sand Filter Low Pressure Issue

[skillset]

I just noticed a problem with my filter yesterday. The pressure was 4lbs lower (14) than expected. I noticed the flow coming out of the returns was reduced. This was perplexing to me since a filter that needs to be backwashed usually has increased pressure. My experience has been that decreased pressure is usually caused by air leaks. So, checking for air leaks, I had none. I backwashed and the filter pressure returned to normal (18) along with the returns flow. I know the filter did not need to be backwashed. Again this morning, the filter was back to being 4 lbs lower again. I quickly backwashed for just 10 seconds, rinsed, and the pressure went back to normal.

I run my pump about 14 hours/day. My assumption is that during the few hours of rest, something is happening in the sand filter that when it's turned back on, the pressure is affected. I'd say it's been at least 7 years or more since the sand was changed.

Looking for advice on next steps (should I change the sand with <3 weeks to go before close) ? I'm assuming running the pump at the lower pressure (if I didn't want "fix" with backwashing) is ok ?

Filter is 2006 Hayward 24" S244T

 

[1poolman1]

I just noticed a problem with my filter yesterday. The pressure was 4lbs lower (14) than expected. I noticed the flow coming out of the returns was reduced. This was perplexing to me since a filter that needs to be backwashed usually has increased pressure. My experience has been that decreased pressure is usually caused by air leaks. So, checking for air leaks, I had none. I backwashed and the filter pressure returned to normal (18) along with the returns flow. I know the filter did not need to be backwashed. Again this morning, the filter was back to being 4 lbs lower again. I quickly backwashed for just 10 seconds, rinsed, and the pressure went back to normal.

I run my pump about 14 hours/day. My assumption is that during the few hours of rest, something is happening in the sand filter that when it's turned back on, the pressure is affected. I'd say it's been at least 7 years or more since the sand was changed.

Looking for advice on next steps (should I change the sand with <3 weeks to go before close) ? I'm assuming running the pump at the lower pressure (if I didn't want "fix" with backwashing) is ok ?

Filter is 2006 Hayward 24" S244T

If all is working correctly, decreased filter pressure would increase the flow. Check for a clog, possibly in the impeller, that may move when there is a change in flow, as in backwashing. Check for a skimmer weir that may be getting stuck in the "up" position, reducing water to the pump. Running at lower pressure should not cause an issue if you want to wait until the next closing/opening.

 

[skillset]

If all is working correctly, decreased filter pressure would increase the flow. Check for a clog, possibly in the impeller, that may move when there is a change in flow, as in backwashing. Check for a skimmer weir that may be getting stuck in the "up" position, reducing water to the pump. Running at lower pressure should not cause an issue if you want to wait until the next closing/opening.

Thanks for the response. Yes - I thought the decreased flow from decreased pressure was very very odd, too.

Anyway, turning the pump on / off didn't resolve the issue. But, you made me think that if this happens again, I should try waste or rinse to see if those modes clears the problem (no backwash). If it does then I guess it's not a filter sand issue (I know backwash mode disturbs the sand). I did install a new pump myself at the beginning of the season and no issues. To your suggestion, I'm assuming the only way to check for an impeller clog is to disassemble the pump? When I'm home later, I'll remove the pump basket and see if there's anything behind it.

 

[1poolman1]

Thanks for the response. Yes - I thought the decreased flow from decreased pressure was very very odd, too.

Anyway, turning the pump on / off didn't resolve the issue. But, you made me think that if this happens again, I should try waste or rinse to see if those modes clears the problem (no backwash). If it does then I guess it's not a filter sand issue (I know backwash mode disturbs the sand). I did install a new pump myself at the beginning of the season and no issues. To your suggestion, I'm assuming the only way to check for an impeller clog is to disassemble the pump? When I'm home later, I'll remove the pump basket and see if there's anything behind it.

To check for a clogged Super Pump, you can, sometimes, reach the impeller through the font of the pump and feel a clog. Or use a short piece of wire with small hook in the end. If there is a clog, you will usually feel it with the wire as it will feel "soft" unlike the hard plastic of the impeller. Hook can help clear it.

 

[Bperry]

Thanks for the response. Yes - I thought the decreased flow from decreased pressure was very very odd, too.

Anyway, turning the pump on / off didn't resolve the issue. But, you made me think that if this happens again, I should try waste or rinse to see if those modes clears the problem (no backwash). If it does then I guess it's not a filter sand issue (I know backwash mode disturbs the sand). I did install a new pump myself at the beginning of the season and no issues. To your suggestion, I'm assuming the only way to check for an impeller clog is to disassemble the pump? When I'm home later, I'll remove the pump basket and see if there's anything behind it.

You can also try knocking the gauge gently to see if it just gets stuck at one spot and backwashing induced a pressure change that reseats it.

 

[skillset]

Thanks again. This is also a great suggestion. The gauge is pretty new, purchased from Amazon in late June and is in excellent shape. Will try to experiment with a few different things tonight. I’ll have to see if it happens again do I really perceive a reduced flow from the returns. I’m pretty sure I did, but will make a conscious effort to pay attention closely.

 

[Mdragger88]

If your gauge has a relief pin on it you may just have built up air in the system. Some filters also have a relief valve.
Mine doesn’t but pressing down & changing the position of the mpv when the pump is off will release the air.
I need to do occasionally this if my skimmer sucks air for some reason.

 

[skillset]

Another good suggestion to try! I just can't imagine a clogged impeller since the pump never runs without the pump basket. But, who knows, maybe something could have "broken off" since the pump motor's only running just over 3 months - nothing's built well these days! Lots of things to consider.

 

[Mdragger88]

Another good suggestion to try! I just can't imagine a clogged impeller since the pump never runs without the pump basket. But, who knows, maybe something could have "broken off" since the pump motor's only running just over 3 months - nothing's built well these days! Lots of things to consider.

Pine needles & hair can get wrapped around the impeller.

 

[skillset]

I have had a ton of small pine needles this season! If this ends up being the issue, I would think that's a removal and cleaning task, which would stink - the motor is butted up against the fence and it was such a pain to change it out back in May. Besides the wire suggestion, any other suggestion that could address potential pine needles without disassembly?

 

[Mdragger88]

 

[skillset]

Thank you for posting this video. I've been doing more reading watched another video and the impeller could be the likely issue - it's just odd that it "fixes" after a change in filter mode for me versus being constant.

 

[skillset]

I cleaned the impeller (did the suggestion in the video) and it appeared clean. No real visible debris although cavity had pine needles (which I don’t think was stuck in the impeller) but can’t be certain. But, got rid of those, fishing them out one by one. Did a test and shut down pump for nearly 5 hours. When I restarted, pressure continued to be normal. The pump was also off for 7 hours last night and pressure was also ok this morning. So maybe something was up with the impeller. Two long rests now and pressure stayed ok when restarted. Will continue to monitor but will be trimming the one pine tree in the fall. Again, thanks for all the suggestions.