Pump running,very low circulation

We just purchased our home in August and it has a 33,000gl indoor underground pool. Up until 4 days ago I haven't had any problems....pretty simple setup and prior owners kept it running and very clean. I wanted to heat the pool up to 80 degrees for company and so I turned heater up, made sure pump was on and didn't check till next day. When I checked temp. the next day it was about 75 degrees so I felt water coming out of jets and there was no water coming out. Timer was turned on to run all the time and pump was running.... but no apparent suction at skimmer and no water coming from jets. I panicked being a new pool owner and shut off the pump and have now spent the last 4 days trying to research and find the problem with no luck yet.

Basic info for pool: one skimmer at side wall with diverter valve and side plate to control flow from main drain and skimmer. 2 jets in shallow end of pool. Centurion 1HP Pump located outside in pump house with heater. Line flow is simple: Line from skimmer runs underground to pump house and then comes out of floor empties into basket, into pump, into STA-rite series 3 300 cartridge filter system, into pool heater, out of pool heater into chlorinator, and then into ground to return jets. There are no shutoff valves on the lines at all. It is continuous flow once it leaves the skimmer.

Here is what I've tried so far. Checked skimmer basket and pump basket for debris, checked pump basket, pump, filter tank, and lines for leaks(none), checked and lubed 0-ring on filter tank and pump basket(seemed fine), cleaned filters they were pretty dirty and look worn-pressure stayed at 20psi which is what it seems to be running at, even took filters out to see if pressure would change it stayed at 20psi. So at this point I'm not sure what to do.....looks like water is coming thru intake line even though skimmer has no suction, the pump basket keeps plenty of water but has a few bubbles at top of lid which has been the norm, pressure is at 20 psi and water is getting into the filter tank. Heater won't run due to low pressure reading so I'm thinking after the filter tank is where the problem is occurring but quite frankly I'm burnt out from so much research. Lastly our temps here in Pa have been really low the last week but the pump was running so it is unlikely that a crack in pipe happened but can't rule it out. Sorry for the long post but I need help and figured as much info. as I could give would get me a fix faster.

Thanks,
Melisa
 
Here are pics of system. How would I clear a clog after the filter? Pump runs fine, no new noises.

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shuye said:
If the gauge is working correctly, shouldn't the pressure climb higher than 20psi if the blockage is after the filter?

Yes. I don't think it can be a blockage. If the blockage was between the pump and filter the pressure gauge would read low. If it was in or after the filter, the gauge would read high.

Unless the normal pressure is very low, the only likely causes to me would be water going somewhere else, or a missing eyeball on one or more returns.
 
Usual pressure is 15-18 psi, so it is a little high but it also stays at 20psi with cartridges out and still no pressure. I only have two jets for return and both have eyeballs. When you say "water going somewhere else" where would it be going? It seems to be flowing through intake pipe to pump and filter then little flow after that. Should I still remove piping from filter to heater and see if there is a clog?
 
Everything's OK with that in-line chlorinator, right? It looks like the water comes out of the heater, through the chlorinator, & back into the pool and that's the only return line.

Can't imagine how that could really be the problem, though, but might as well check everything.

Oh, BTW, is that a 2-speed or variable-speed pump? Could you have it on low speed?

Good luck!
 
Chlorinator had some chlorine tablet debris in it so I took it off and emptied it, other than that it looks fine. Our pump is hooked up to an on/off switch at the pump and as far as I know that is the only thing you can do to it. Sorry I am totally new to all this but there is no low or high speed on the pump. If you can tell anything else I might be missing from the picture of the pump please let me know.
 
The only other thing you could do first is disconnect the union at the pump outlet. If the pump creates a crazy fountain and the flow is good at that point, you know your problem is further downstream. Of course, know that it will make a total water mess, and not knowing what your equipment space is like, you'll have to decide if you want to do that.
 
So I took the pump motor off and checked the impeller, it is in great shape and had no clogs. That said I doubt there would be a clog in the return lines considering it is an indoor pool with little debris and pump basket and impeller are free of debris. I did notice a lack of 0-rings but it looks like they sealed the pump motor with silicone caulk. Also the diffuser did not come off with motor but it looks like it is still attached to pump basket(won't come off). I also ran a plumbing snake down the skimmer line to check for clogs and found nothing. If my pipes cracked due to cold temps how would I go about checking them to find the line with a leak? They are run underground, is there a pressure test to do??(really hoping this is not the problem)

Any other ideas about what could be causing such low return circulation?
 
Even with an indoor pool, toys can get sucked into the skimmer lines and cause a clog. You might try back flushing to see if anything comes out.

Also, when you had the pump apart, did you notice if you turned the impeller that the motor turned too? Sometimes the impeller nut can break loose so the motor doesn't spin the impeller effectively.
 
Hubby speaking...

First off, I would like to thank each of you for your help in troubleshooting. I have been out of town since January 1st and with your help my wife has stretched well beyond her comfort zone in tackling this for which I am proud/grateful.

In putting my hands to the issue myself this evening, I feel 99.9% confident that the issue is a blockage within the pool heater itself. As she still had the pump off, I checked the impeller connection by running the pump with it still loose and then grabbing the pump with gloved hand. The impeller is certainly attached fine.

Next I put the (now cleaned) cartridge filters back in place as the issue existed even with them removed. I had been doubtful from afar that they were the issue anyway as things were fine in late December when I was last in the pool and I would expect a filter to clog/restrict slowly rather than all at once which seemed to be the case.

Filling the pre-filter basket with water and running the pump, pressure quickly built in the filter. It hovers between 22-23 psi after bleeding off the air. At this point I can CLEARLY feel good flow entering the heater manifold. The flow exiting the heater is nil. I took the lid off the near empty chlorinator and it barely has any water feeding into it.

This leads me to my conclusion that the water heater is my issue. From here I'm not exactly sure where to start however. Heater is a Hayward H-series 50-034 350k BTU heater. Anybody with experience here, I'd be happy to hear it.

Thanks again to all whom helped to this point.
 

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