Stopped getting good suction from pump

[sidewalk]

I'm a new pool owner, inheriting an in-ground pool from a previous owner. I had some initial suction issues when I opened the pool but after changing O-ring, I started getting full force again. Then yesterday, it started drawing at what seems to be about half power. It's definitely not enough suction to get a quality suction at the skimmer. Since I've already changed O-rings, I'm not sure where else to go. This morning I wrapped thread tape on the PVC connectors but that didn't help things either.

I have had to restart the pump, clean the filters, etc. several times a day due to how filthy to the pool was. Yesterday, the filter was running great and had churned through an algaecide treatment the night before. The cartridge filter was completely covered after doing that. My concern here is if the pump's internals might be clogged up with algae as well. I did shock the pool last night, so if that were the case, I think it would help that out. I essentially started losing pressure sometime after I shocked it.

This is my pump:

Harris H1572748 ProForce Inground Pool Pump, 115/230V, 1.5 HP

SAVES YOU $150 OVER HAYWARD!Carborundum & graphite mechanical seals for longer life and quiet operationLarge capacity extra leaf holding basket while allowing for free flowing operationSee-through strainer cover lets you see when the basket needs to be cleanedSelf-priming (suction lift up to 8'...

www.poolsuppliessuperstore.com

Does anyone have any ideas on what might be happening here? There are certainly things I could do (new pump lid, redo all the PVC, etc.) but that seems like a fishing expedition! Would prefer a more focused approach to solving this.

 

[Texas Splash]

Welcome to TFP! Sounds like you may have a couple issues at the moment - poor suction/water flow and algae. So let's discuss both.

Poor water flow can be several things:
- Suction side air leak (check all O-ring and make sure they were lubed with pool silicone
- Weir door flap not operating properly at the skimmer
- Water level low
- Partial clog
- Even a heavy blockage at the filter rcan impeed water flow ... which takes us to ........

Algae, requires a TFP SLAM Process. Algeacides do nothing, neither does a one-time shock. Do you have a TF-100 or Taylor K-2006C test kit? That's step #1. See Test Kits Compared. From one of those kits we would like to see a full set of water test results. Then we can help guide you. Also take a moment to update your signature with all of your pool and equipment info. We'll refer to it all later. Let us know if you have any other questions.

Suction Side Air Leaks

If you see air bubbles coming out of the return lines in your pool, you likely have a leak. Some signs that a suction side plumbing leak has occurred include: Read more

www.troublefreepool.com

 

[sidewalk]

Would any residue or anything like that in the water from the SLAM process cause the pump to lose suction power?

Last night I started with 4 pounds of 75% shock (35k gallon pool) and was planning to do so tonight and tomorrow night as well. I had decent suction all day yesterday until I added that shock. It was powdered shock and not liquid but it was very fine and was spread pretty evenly in the deep end, so I don't think there is a big build up in the lines anywhere or anything like that, although I suppose that's possible as well.

 

[Richard320]

Pine needles in particular but any kind of twigs or straw can slip through the baskets and clog the pump impeller. The pump will sound normal but there will be little or no suction, little or no flow, and very low pressure on the filter gauge. Have you been vacuuming up anything like that?

 

[sidewalk]

I don’t think. Biggest culprit is leaves and those are rarely even making it to the pump basket let alone get past it.

I’m not getting much volume but the pressure gauge on the filter is around 15-20 which is where it was when it had full suction.

 

[Richard320]

I don’t think. Biggest culprit is leaves and those are rarely even making it to the pump basket let alone get past it.

I’m not getting much volume but the pressure gauge on the filter is around 15-20 which is where it was when it had full suction.

So which is it? If you started at 15 and now you're at 20, you're late with a cleaning. It should have been done at 18 or 19. Cartridge and DE filters will both load up in an hour or two if the pool is thick and green.

 

[sidewalk]

The pressure meter is scuffed to the point where it’s hard to tell exactly.

I have been cleaning/swapping filters once or twice daily but maybe need to step that up. Would a dirty filter impact the suction side though?

 

[Richard320]

The pressure meter is scuffed to the point where it’s hard to tell exactly.

I have been cleaning/swapping filters once or twice daily but maybe need to step that up. Would a dirty filter impact the suction side though?

Yep. All a pump does is take in water and send it out the other side. If it's got nowhere to send it, it doesn't take any more. Take the cartridge out and reassemble it and run things. If the flow improves tremendously, it's the cartridge. If it's still sluggish, you got some other problem.

 

[RonsPlc]

I run my pump on low speed all the time, and can tell if the filter needs to be backwashed by the flow going into my skimmer.
If the skimmer is looking like it has weak flow, that is my que to do a backwash. If it still has weak flow after the backwash, I start looking for other reasons.
So in short, YES, low skimmer/suction can be caused by a stopped/restricted filter. Picture not being able to exhale... you will soon find it hard to inhale.

 

[sidewalk]

Cheers to y'all! I have two cartridges that I've been swapping out and cleaning. Sure enough, I changed them out and we're back to full suction!

The filter I took out actually didn't look that bad but I guess I just need to be on a 2 or 3 hour rotation rather than 12 hour until this pool gets cleaned out.

 

[sidewalk]

Well my excitement was short lived. The suction reduced quite a bit after about 20 minutes. I let a filter soak overnight in cleaner and put it in this morning. Again, great suction that died down after 20 minutes.

I have two filters. One was brand new the other was used at least last year, I don't know if it was used any more than that. I wouldn't think the brand new filter would be so worn down already that it's failing that quickly. I did order a third one that will be here tomorrow but I'm wondering if something else is going on.

Is it safe to just remove the cartridge and run the system without it? That way I could at least debug if the cartridge actually is the culprit.

 

[RonsPlc]

Can you run your filter without the filter cartridge in it?
If you can, you might want to try that, and see if it runs right for 45 minutes.
Cartridge filters are good, but when dealing with excessive loads they do tend to clog up quick.

And if you can, please fill out your signature to tell us what type of equipment you are dealing with.
Take a look at my signature below, or Richard320's one above for examples.
Be as specific as you can. That will help us to help you.

 

[Texas Splash]

Yep. I'm going to refer back to my first post in post 2. Algae. This would be a good time to see a full set of water test results.

 

[sidewalk]

I've been running the pump w/o the cartridge for about 45 minutes now and the suction is incredible and holding steady.

I've been dumping chlorine in the past two nights to clear up the pool. The pool store told me not to worry about measurements until I do a third night of chlorine treatment. I can still take measurements but the chlorine levels are probably going to be pretty high.

I suppose it might be good to vacuum to waste and get some of this stuff out before I try using the filter again.

 

[RonsPlc]

In my signature, you will find a link to "Pool School".
Do yourself a favor, and read it. It explains a lot about the whys, and hows.
There is another link for test kits. We have learned (the hard way for most of us) that pool store testing is NOT to be trusted. Get a good test kit, and take control of your pool. You won't regret it.
Oh, and WELCOME to TFP.

 

[sidewalk]

I got readings of this with my test kit (it's a 5-way HTH kit):

Total Chlorine: 5
Ph: 8.2
Alk: 160
CA: 70

Hardness did not register.

I'll need to buy a better test kit as recommended but this is what I have for now.

 

[RonsPlc]

The HTH kit is fine for when you have your pool CLEARED of algae, and want to do a fast check of your pool.
But for the levels that are required to eradicate it, the FAS-DPD test is needed, as is a CYA test to determine the chlorine level you will need to hold for the SLAM.

 

[sktn77a]

Well, your chlorine is OK for normal swimming but not high enough to SLAM the algae. You definitely have bad algae and that's what's plugging up your filters. SLAM the you-know-what out of the pool (it may take 2-4 small bags of granulated trichlor or cal-hypo "shock" or several gallons of liquid bleach - you need a FREE chlorine of 20-30). Your pH is too high which can cause staining and cloudiness - add 1/4 gal muriatic acid (that should reduce the Alkalinity some, also).

 

[sidewalk]

I’m not sure what to do about filters at this point. I soaked one in filter cleaner overnight and washed it thoroughly and still can’t get suction with it. At $70 a pop I’m not going to start fresh with new ones every day!

Will vacuuming to waste capture enough of those particles so I can just buy a new filter and be done with it for the year? The stuff needs to get out of the pool and if running it through the filter is too taxing to the filters, vacuuming or draining seem like the only other options.

 

[sidewalk]

In case anyone searches for a similar problem and finds this thread, I wanted to go ahead and conclude it.

The amount of dirt and dead algae in the pool was essentially blocking up the cartridge filters within minutes. Although the filters didn't look that bad, they really were.

Since the pool was very cloudy, I used Floc to clear things up and knock the grime to the bottom. This was an absolute pool saver! After letting the Floc work for around 24 hours, I had enough clarity in the deep end to see all the dirt. I vacuumed the pool to waste to get all that dirt out, which took about an hour so there was a fair amount of water loss. I then had the pool topped off to recommended level and we're crystal clear now! Full suction with a new filter installed that isn't getting destroyed within minutes.