Pump Losing Outlet Pressure/Flow

[Chevydue057]

Hey everyone, I opened my pool a little late this year, and for the first time in 5 years I had a green pool when opening it. There were a couple of rips in the cover, and I'm guessing a lot of Crud got into the pool over the winter.

Anyway, I cleared everything out, got the filter and pump running and the algea started clearing up. Green is gone, and trying to maintain a slam, while the cloudy water clears up, but some some reason the pump keeps loosing pressure. What I mean is the output pressure from the return jet keeps dropping.

After a couple of hours, last night, It did it. There wasn't enough in the skimmer basket to cause it, but I cleaned it out and restarted it. Turned it back on, it was okay. Checked it a little while later, same thing.

I back washed the filter this afternoon, got some dirt and gunk out, rinsed it, and tried again. After a little while, same thing. The water is cloudy, but it's not full of large debris, the filter can't be clogged again.

What's going on with the pump? The strainer basket in the pump doesn't have a lot of junk in it either.

Again, it runs for a while then looses pressure out of the return eyelet. What am I overlooking?

When the outlet jet loses pressure, if I turn the pump off, and then turn it right back on, it's back to normal pressure. For a short time.

 

[cowboycasey]

your filter is doing its job.. What is your pressure in the filter at when the flow slows down? what is the pressure after you backwash?

 

[Chevydue057]

Pressure after the backwash was about 15psi.

Pressure when you first turn the pump on is 20psi. Pressure when the flow/pressure in the outlet is reduced it 22psi.

 

[cowboycasey]

15 PSI after backwash is your pressure so you will need to backwash at 25% or 19 PSI.. at 22 PSI the flow is almost stopped..

 

[Chevydue057]

I completely agree.

I guess, I'm just confused how the 150LB sand filter can clog 2X after running for an hour or two each time.

The sand was replaced this year because I replaced the spider gasket on the multiport pump. So it was brand new. I backwashed last night and when I checked the filter after running for an hour it's the 22psi. Without large derbris getting sucked in, can the filter really be clogging this much?

It's running now, because the water is still cloudy, but I will backwash tonight after work. Should I be trying to investigate another problem?

Also, just for an information point, If i turn the pump off and back on, the pressure drops a couple psi and I have full flow for a while. Maybe the filter is actually just clogging this quickly. but in the off chance there was something else to check, I wanted to put it out there.

 

[cowboycasey]

Your in the middle of a SLAM and the filter is doing its job cleaning the dead algae out of the water... It is working better then before and that is what is throwing you off... If the pressure hits 19 in 2 hours then you need to backwash every 2 hours.. That is a perfect time since you can test and adjust your FC level for the SLAM..

 

[Chevydue057]

Your in the middle of a SLAM and the filter is doing its job cleaning the dead algae out of the water... It is working better then before and that is what is throwing you off... If the pressure hits 19 in 2 hours then you need to backwash every 2 hours.. That is a perfect time since you can test and adjust your FC level for the SLAM..

Thank you. That makes sense! I guess I panicked and was assuming something was wrong with the pump and filter system. 2 hours or less seemed way to quick to clog the filter, but I'll continue with the method. Thank you!

I'll backwash and continue.

 

[Chevydue057]

Well, I just wanted to update. I have continued running the filter, and around every 3 hours or so, the outlet from the return jet diminishes in pressure and flow significantly. I've backwashed each time and I'm really not getting a lot of junk out of the filter. Sure, its a little dark, but nothing that looks like it would be from a clogged filter. And it runs clearish pretty quick(timed it to be under a minute 3 times).

Something I did notice though, is when the pump looses pressure, if I turn the system off and then back on, it's immediately back to full pressure. And in a short time it'll go back down, like an hour or so. If the filter was clogging, shutting the system off and turning it back on should yield the same reduced flow, right?

I'll post some photo's of the plumbing and setup tomorrow, maybe there is something wrong. I certainty didn't notice this last year, and all I did was lube up the selector handle and replace the spider gasket in the multi port valve ( i have another thread about this, that I may update).

I don't think I've backwashed my filter this many times in an entire season previously, it seems very excessive, and while the water is a little cloudy, there isn't large debris in the water.

 

[Texas Splash]

People often underestimate the effects of excessive organics in the water when it is transparent and can't be seen. Your pressure systems resemble that. The SLAM Process needs to continue to the letter. You don't have PoolMath test logs linked to your TFP profile so I can't see your testing. How about posting a set of water test results?

Also, please update your signature with all of your pool and equipment info. Include your test kit as well.

 

[Chad1979]

Dead algae is very small and hard to see until there is a lot. In 2 or 3 hours your filter is collecting a LOT of it. Your system is filtering it out like it is supposed to. Your suggestion of just turning pump off and back on will not help as the junk will still be in the filter. You need to backwash it out when your pressure rises to 19 to ensure you keep filtering out the junk effectively.

 

[JohnT]

How long are you backwashing?

 

[Chevydue057]

People often underestimate the effects of excessive organics in the water when it is transparent and can't be seen. Your pressure systems resemble that. The SLAM Process needs to continue to the letter. You don't have PoolMath test logs linked to your TFP profile so I can't see your testing. How about posting a set of water test results?

Also, please update your signature with all of your pool and equipment info. Include your test kit as well.

I clicked on the pool math and it wanted me to download an app. I'll play with it later and see if I can't link that all up so you guys can see the pool test results. Good call on the signature, I'll go get all the specs and add them to my signature too. You may be right, the water was green, then cloudy so it might actually just be collecting that much fine particles.

Dead algae is very small and hard to see until there is a lot. In 2 or 3 hours your filter is collecting a LOT of it. Your system is filtering it out like it is supposed to. Your suggestion of just turning pump off and back on will not help as the junk will still be in the filter. You need to backwash it out when your pressure rises to 19 to ensure you keep filtering out the junk effectively.

I think I'm just trying to make sure I don't still have a filter/pump problem. Last year, when running the pump I would get visible sized debris and it wasn't algae. It was dirt/soil that was getting passed the filter, and after much headache and troubleshooting it was suggested the spider valve gasket must be leaking and allowing dirt through. During this current SLAM I am getting a lot of dirt and debris in the center of the pool that needs vacuuming out, so I fear my problem from last year is still present. I checked the pipe and laterals very closely and looked at the sand for anything off and I saw no sign of cracks or anything wrong. My brain just can't help but wonder why turning the system off for 10 seconds and turning it back on restores full outlet pressure for an 30 minutes to an hour. I am continuing to backflush when the filter is at 19psi/20psi. I just adding data or things that I've found.

How long are you backwashing?

I'll give the long answer, in case I'm doing something wrong I can be corrected. Approximately 3 minutes. The first 30 seconds or so it's clear, the next 90 seconds to 2 minutes are dirty, but not very dirty. Blackish water. The it'll run another 30 seconds or so cloudy and clear up. When it runs clear for 30 seconds or so, I turn it off and switch to rinse for another minute.

 

[Chevydue057]

*UPDATE*:

So the outlet pressure dropped again, but today the pressure gauge was only at 15/16psi. and when it did that, I could see bubbles in the top of the pump. I watched it for a while and it got worse, more bubbles, bigger bubbles. It seems as if the pump was sucking in air. I checked all the connections, I took out the drain plug, and resealed the threads, and put it back together, and the pump is back to 15/16psi and full output. Been like this for about 9 hours at this point. Maybe the pump was pulling a little bit of air over time and some how air locking part of the system, I don't know.

I'm going to give it another night and see what happens, but the water has cleared up significantly in the last 9 hours, I wouldn't say it's 100%,, but It's close.


But, I'm back to the problem I had last year, when the filter is running, dirt settling in the middle of the pool. Which is weird, because the filter works enough to get the algae out of the pool, but dirt settles in the center. But I might bump my thread from last year, and try to pick up from where I eft off.

 

[Chad1979]

Sounds like your backwash is being done long enough. Does your pool stay covered all the time or is it open? My little pool gets dirt and debris in it just by sitting there with no breeze. Bugs, pine needles, dirt, etc. I think yours gets some that way as well. if your pool has a good circulation current, debris amd dirt typically will be focused in the center of the pool along with any other debris that makes it into the pool but evades your skimmer.

 

[Chevydue057]

Sounds like your backwash is being done long enough. Does your pool stay covered all the time or is it open? My little pool gets dirt and debris in it just by sitting there with no breeze. Bugs, pine needles, dirt, etc. I think yours gets some that way as well. if your pool has a good circulation current, debris amd dirt typically will be focused in the center of the pool along with any other debris that makes it into the pool but evades your skimmer.

My pool does sit open. I have a solor cover, but I don't have a good method to put it on and off and the store build cover roller doesn't fit too well in the area around my pool, so I hardly ever use it. I've done everything else, checked everything the last two seasons, you might be right.

I do have trees near the pool, and it might just be dirt/debris getting in the pool. Maybe I'm chasing a ghost for nothing. But, that means something changed in 2019 or so, because the first couple of years I had the pool I didn't have this problem ( I bought a house with an existing pool). Thank you!