Pump loses suction after 20 minutes

[wags22]

I have a Pentair VS 3050 intelliflow pump that keeps losing suction after 20 minutes.

My pool is a uni-body with 2 inlets directly into the pool and 1 into the spa, water then flows over the wall into the pool.

Filter is a 48 sq ft DE filter that I took apart and cleaned out a couple weeks ago. Pressure gauge doesn't change between when flowing and when it stops. Back flushing does get the flow started again but it stops after 20 min (or less).


Some pictures are posted below, don't know if they'll help. I took video, but can't get it to upload despite being under the size limit.

Thanks in advance for any assistance.

Regards,
Jonathan

 

[Texas Splash]

Hey Jonathan! Well, a primary concern for me is the algae-filled water and lack of visibility to the pressure (bad gauge). Since flow seems to be okay following a back (flush), I have a sneaky feeling your water is so full of algae (visible in the image) that your filter is clogging right away. The gauge isn't telling you that of course.

I would order a new gauge ASAP from TFTestkits.net. They are nice glycerin-filled gauges at a great price. By "backflushing", so you mean you have a plunger valve? Or do you have a multiport to where you can backwash or simply circulate? If just a plunger, you're kind of stuck. But I suspect flow is being restricted by algae.

Are you trying to do a "SLAM" (link below)? Do you have a TF-100 or Taylor K-2006C test kit to perform a SLAM? That's a critical issue as well.

Let us know and we'll try to assist some more if you like. Thanks for using the forum.

 

[wags22]

Pat,
I think you might be right with it being the algae. Is there a best practice for getting the algae filtered out? Can I clean the filter and just not add D.E. until I've got all the visible algae out?

This is the state my pool is in after the winter with no cover on it and I was running the pump for about 4 hours a day. I know that I have neglected it over the winter, primarily for financial reasons. I'm trying to get it back in use as low cost as possible.

I'm not sure if what I've done exactly fits a SLAM. I added PhosFree+, a couple packets of Shock, and some algaecide about a week ago to kill off what was growing, now I'm just trying to get it cleaned up.

Thanks for the help.
Jonathan

 

[Texas Splash]

I added PhosFree+, a couple packets of Shock, and some algaecide

Sorry to say, but those products just ate-up some $$. Ugh. Stick to "regular" plain bleach. What you've done so far doesn't meet the SLAM criteria (link below). To perform a SLAM, you'll need a TF-100 to Taylor K-2006C test kit. Had you found us sooner, the money spent on those other products probably would've paid for a test kit. But to do the SLAM, you need to start at 3 key tests:
- Lower pH to about 7.2
- Test CYA because the proper SLAM/Shock level is based off of the CYA
- Be able to test and maintain the elevated SLAM FC level with the proper test kit.

That's the cliff notes version. So as soon as you can verify those three things, you'll be on your way to performing a SLAM the right way. We hate to see you dump money and time using pool store products that simply won't remove all the algae. As for the filter, you'll end-up cleaning the grids a lot I'm afraid. Folks love DE for the filtration quality .... except when a SLAM is needed. You might get by (on rare occasions) running in by-pass or circulate when you're away from home, but otherwise you'll be filtering a lot of algae.

 

[wags22]

From what I read of the SLAM process, I'm going to have to babysit my filter until the algae is cleared out. Is there a way to break the algae it down further, or is repeated vacuuming and constant circulation the only way to get rid of it?

 

[Texas Splash]

From what I read of the SLAM process, I'm going to have to babysit my filter until the algae is cleared out. Is there a way to break the algae it down further, or is repeated vacuuming and constant circulation the only way to get rid of it?

You may be able to remove clumpy or stringy algae, but the finer "cloudier" stuff will be weakened by the bleach and caught by the filter. You will be doing a few extra backwashes for sure, but eventually even that will slow down.

 

[wags22]

I took the filter cover off, lifted out the grid assembly, sprayed it off (didn't disassemble the grids, wasn't much D.E. on them). Put it back together and sealed it up. Still getting the loss of suction. Water is moving slowly, but still losing it. Even when I took the vac-mate off and the cleaner is no longer on, it loses suction. I'm going to let it run as is overnight just to see if it will clean it up, but I'm completely baffled as to what is going on.

 

[wags22]

Had to fix a blown apart fitting (wrong glue used when putting it together a few years back). The a couple days of high wind that prevented me from doing any work.

I took the hose and ran water back through the inlets, doesn't appear to be any clogs.

When I start the pump, the pump basket only fills about half way. When I open the backwash valve it fills completely. This says to me that I've got a pressure side blockage, most likely in the filter, but I'm clueless as to why. The filter has been cleaned out completely, there is no D.E. in it. Backwash is clear. Is there such a thing as the grids becoming blocked? Is there something I can add to clear them out? Or a process to clean them outside of the filter housing?

Thanks again for the help.