I have an inground pool with a Hayward sand filter that is about 7 years old, and it had no issues until about a week ago. Last weekend, I noticed that the filtration pump was making a strange noise. Upon further investigation, I discovered that the pump was cavitating. When I troubleshooted, I refilled the pump's water reservoir, which caused the pump to work briefly before cavitating again because it wasn't pulling in water from the pool. I disconnected the hose from the pump to the filter, and the pump worked with no issue and with a strong water flow. However, when I reconnected the hose back to the sand filter, the pump started cavitating again. A friend who sells pool parts told me that the problem is the 7-way multiport valve, and I would need to replace the gasket on the inside of the valve assembly or buy a new one to fix the issue. When I took it apart, I noticed that the white gasket on the valve assembly appeared to be worn down. While it's plausible that this is the issue, I wanted to ask for everyone's perspective on what might be causing this issue. Thanks in advance for the help.
Please Help...Pool not circulating
- Thread starter Thomas45
- Start date
- Jun 22, 2014
- 52,194
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Welcome to TFP! 
Before you go any further and start tearing things apart, I would first rule out the easiest thing - chemistry. Excessive build up of organics can be extremely disruptive to water flow. Very bad. So let's start with a full set of water test results from either a TF-100, TF-Pro Series, or Taylor K-200C. Can you post such results?
Before you go any further and start tearing things apart, I would first rule out the easiest thing - chemistry. Excessive build up of organics can be extremely disruptive to water flow. Very bad. So let's start with a full set of water test results from either a TF-100, TF-Pro Series, or Taylor K-200C. Can you post such results?Although I am not sure of the results, I have the pool water tested weekly at the local pool store. There is no obstruction due to when I completely bypassed the filter and the water circulated with no issues,Welcome to TFP!
Tom,
It sounds to me like your problem is the sand filter..
The fact that you can by-pass the filter, and it works, proves this point..
It could be the MPV or the filter itself. Since you can by-pass the filter using the MPV, then I would assume it is the filter.
Thanks,
Jim R.
Last edited:
- Jun 22, 2014
- 52,194
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
You'll find here at TFP we place absolutely ZERO faith in pool store testing, and no better with their advice. When I said above that you would be surprised how badly poor chemistry can effect water circulation, it is amazing. Again, the description you provided could support that theory. You can tear the filter apart if you wish, but if it were me I would start with ensuring first & foremost you are testing the water yourself (with a proper test kit noted above) and perform an Overnight Chlorine Loss Test to ensure organics are not clogging your filter. We see this all the time.
- May 3, 2007
- 18,169
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
With a residential pool pump, cavitation is heard not seen. With true cavitation, the pump sounds like rocks are traveling through it. If by cavitation, you are seeing air in the pump basket, that is an air leak and not cavitation.
Has the filter pressure changed at all since the last time you cleaned the filter? What was/is the filter pressure?
Has the filter pressure changed at all since the last time you cleaned the filter? What was/is the filter pressure?
Thank you for the expertise. This is what I am not sure about because when the actual filter itself is bypassed, the pool circulates with no issues. When connected back to the filter, it doesn't matter if the multiport valve is on circulate, or filtration, the pump starts to cavitate, When the valve is moved to rinse, the water is extremely slow and the pump cavitates as well. Just curious are there are other parts inside the MPV besides the gasket that could go bad? Looking at the MPV, I will need a new pressure gauge, spider gasket and the label that gord opn the very top of the valve.
- May 3, 2007
- 18,169
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Pumps cavitate when the suction gets too high (NPSHa < NPSHr), not when the return gets restricted.
- Jun 22, 2014
- 52,194
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
@Thomas45 , please post a couple pics of your equipment pad so we can see your filter and plumbing lines.
When I attempt to backwash, the pump cavitates and the water is extremely slow coming out
Tom,
Just so that we are all on the same page, when you look through the pump lid, what do you see when you say the pump is "Cavitating"??
Thanks,
Jim R.
Just so that we are all on the same page, when you look through the pump lid, what do you see when you say the pump is "Cavitating"??
Thanks,
Jim R.
Can you show the system?
Maybe the plumbing is incorrect with the lines going to the multiport being incorrect?
The line from the pump goes to the top port.
Maybe the plumbing is incorrect with the lines going to the multiport being incorrect?
The line from the pump goes to the top port.
When I look through the lid, the pump is not pulling any water from the pool.
Thanks, everyone for the advice.. Finally made it home yesterday and was able to troubleshoot more. I have to admit now I am completely confused. When I took the MPV top off, the water ran strong for about 30 secs before not flowing and the pump "appeared" to start cavitating. I noticed the pump had stopped pulling water from the pool inlet pipe. I checked the impeller on the pump and they did not appear to be impaired. However, if you prime the pump reservoir and turn it back on the pump will run strong for about 30 seconds before the same thing happens again......I have a video, but cannot figure out how to upload it, so if someone can help that would be great. Until then, here is a picture of my pump setup.
- May 3, 2014
- 62,945
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Thank you for the help. Please see the video that shows how the pump will barely pump before suddenly pumping great, only to slow down again.
The water will flow, although it doesn't seem to flow at a high rate like when the top is off the MPV. One thing the video doesn't capture is after a few minutes, the pump will stop pulling/sucking water from the pool inlet pipe and start appear to cavitate. There is a video of the pump reservoir....