Vacuum Issues

[NicDMX]

Whenever I hook up the vacuum, the pump loses prime and suction is extremely low. I've hooked up the vacuum hose to a skimmer basket and plugged off the other skimmer to maximize suction. I've ensured the hose is completely filled with water when hooked in to the skimmer basket. The pump will stay fully primed and at full power until I plug in the vacuum hose--I get a few seconds of good suction, but then the pump loses prime and suction.

Any ideas what could be wrong? The pump pulls strong through the skimmer until I put the hose in place.

There appears to be a very tiny amount of air getting in to the system, nothing significant, but I see a small amount of bubbles coming through one of the returns when the pump is running. I've had a leak on a poor pvc job after a fence installation hit some underground plumbing, and this is a significantly smaller amount of bubbles than occurred during that time, so its hard for me to think that is the culprit, but I could be wrong.

 

[woodyp]

If you're using the vacuum plate in the skimmer....take it out and put your vac hose directly in the skimmer hole at bottom.

 

[NicDMX]

If you're using the vacuum plate in the skimmer....take it out and put your vac hose directly in the skimmer hole at bottom.

I don't think I have a vacuum plate. I was was putting the hose directly into the skimmer hole at the bottom.

 

[Dirk]

Sounds like there might be a hole or tear in your vacuum hose. Is it one piece? Or sectional? If it's sectional, take a section out one at a time and see if the problem goes away. If not, does half of it float while half is underwater? Are both ends the same? Swap the ends (so the half that was floating is now under water) and see if the problem goes away. These are troubleshooting techniques, to help you find where the leak is. Alternately, after filling the hose with water and connecting to the skimmer port, lift the entire hose out of the water, laying it on the deck, and just keep the the last few inches in the pool. Have someone or something hold it there, then look/listen along the hose for a leak.

 

[PoolGate]

I pretty much have the exact same issue. I found that my pump just pulls too hard for only one port. I suspect the pump is cavitating. Like you, I (used to) shut off my floor drains and 2nd skimmer. I found that if I just shut off the floor drains and hook it up, it works pretty well. Then I slowly close off the other skimmer until the basket starts to get air in it. I back it off a little and that is where I run it. PLENTY of suction to clean anything in the pool. I vacuumed the entire pool yesterday like this.

 

[Melnic]

To add to the above suggestions to try, does the same thing happen when you use the other skimmer?
Do you see bubbles/air at the pump strainer basket lid?

 

[NicDMX]

The hose is a brand new one, so it shouldn't be leaking, although I can't rule that out yet.

I've tried using both skimmers. I don't really have the option to back off the valve given my plumbing. I can close off one of the skimmers with a rubber plug, and the other I have to close the deep port with a plug (to stop flow from the main drain, and then another plug on top of that to stop flow from the skimmer. I don't have a separate valve to adjust how much a skimmer is taking. I will mess with it some more though and try to create a similar effect, perhaps with a partial blockage.