Problems with vacuum connected

[diggler86]

Hi

New pool owner (of an old pool)..

Everything appears to operate normally when using just the skimmer. Operates at 12PSI with no air in filter or return jets. There is a small pocket of air in the pump basket that has always been there. Might see one or two tiny air bubbles come in from the suction tube every second.

If I hook in the manual vac, the filter PSI goes very low to about 4 and there is not a lot of water in the pump basket. Pump quite loud. Should this happen?

If I hook in the barracude g3 vac, the filter PSI goes to about 8, and there is a stream of air bubbles in the return jets as well as accumulation in the filter.

With either vac, the pump water is too much sloshing to see if there is more bubbles coming in from suction side.

The pump lid has been cleaned & lubed with no improvement. Have checked for any leaks in suction side pad with shaving cream and water did not find any. Have tried new zodiac hoses with no difference. Manual vac hose is new.

Any final ideas before I have to shell out bucks to have suction line pressure tested? My only theory is that there is an air leak which gets worse with added vacuum. Or an obstruction only seen with added vacuum. Dont know how to test for that.

I have not checked the impeller yet. Been tired of spending all weekends troubleshooting. Could this cause this behavior or would it not even operate normal on skimmer?


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20k gal in ground, FNS plus filter, pentair pump, one skimmer inlet to pump (pentair u3)

 

[Bama Rambler]

Your theory is correct. You have a suction side air leak. The fact that you see a few bubbles coming into the pump basket also supports the diagnosis.

I would spend a little more time trying to find the leak before calling a leak detection company.

Did you remove the drain plugs and clean and reseal them?

Pay close attention to the suction port on the pump.

 

[JohnT]

If you only have a single skimmer, you need to be using an adjustable skimmer plate to keep from starving the pump. Your hose can't provide enough water alone.

 

[bobodaclown]

Check the hose. Dragging/wear can cause pinholes in the hose.

 

[diggler86]

Your theory is correct. You have a suction side air leak. The fact that you see a few bubbles coming into the pump basket also supports the diagnosis.

I would spend a little more time trying to find the leak before calling a leak detection company.

Did you remove the drain plugs and clean and reseal them?

Pay close attention to the suction port on the pump.

Thanks for reply.

Since I've seen the small bubbles come from the suction tube, I havent tried resealing the drain plug. I also read that when you shut off the pump you'd likely see or feel some water there. So I decided not to touch it at this time and potentially introduce another variable.

I've tried everything I have read to troubleshoot on the above ground pad equipment. I have a bad feeling that it might be something under the skimmer. Some of the concrete around the skimmer that looks like it was repaired at one time has risen and broken the flex grout between the concrete. The skimmer itself looks about 1/4" risen above the concrete. Wondering if water is getting under there somehow related to this leak. Seems like I lose more water when the pump is running (I know thats usually pressure side, but...).

The plumbing is old metal and I have read it could have pinholes after 30 years. Its probably at that age. Hopefully not because its a long and complicated run back to the pad.

 

[diggler86]

If you only have a single skimmer, you need to be using an adjustable skimmer plate to keep from starving the pump. Your hose can't provide enough water alone.

With the zodiac connected, its got the flow valve connected. Its my understanding this is to regulate how much vacuum is provided so it can climb walls etc.

With a manual vac, I dont really understand your comment, or have seen an adjustable plate available (only for auto vacs). The hose is just an extension of the plumbing. I realize that perhaps the PSI would decrease a bit due to more vacuum necessary, and the motor may work harder, but I dont see where air would be introduced instead of water. Wouldnt the pump basket still be full of water? The water being "provided" through a 60' hose would be the same as through a 30' hose. Just requires more vacuum, correct? Seems the only possible place the pump could have the chance to suck in air would be the pump lid in that case.

- - - Updated - - -

Check the hose. Dragging/wear can cause pinholes in the hose.

Manual vac hose is new. Have tried creating short section of 4 brand new pieces for zodiac with same issue.

 

[JohnT]

With the zodiac connected, its got the flow valve connected. Its my understanding this is to regulate how much vacuum is provided so it can climb walls etc.

With a manual vac, I dont really understand your comment, or have seen an adjustable plate available (only for auto vacs). The hose is just an extension of the plumbing. I realize that perhaps the PSI would decrease a bit due to more vacuum necessary, and the motor may work harder, but I dont see where air would be introduced instead of water. Wouldnt the pump basket still be full of water? The water being "provided" through a 60' hose would be the same as through a 30' hose. Just requires more vacuum, correct? Seems the only possible place the pump could have the chance to suck in air would be the pump lid in that case.

- - - Updated - - -



Manual vac hose is new. Have tried creating short section of 4 brand new pieces for zodiac with same issue.

First, are you filling the hoses with the water from a return before connecting them?

Air isn't being introduced. It's just a lack of water that causes the bubbles and churning. The pump is pumping water out of the basket as fast as it can, but the hose can't provide water to the basket as fast as the pump empties it. The hose adds a lot of restriction to the plumbing.

An adjustable plate allows some water to enter the skimmer directly to keep the pump fed while still pulling enough water through the hose for the vaccum to operate.

My pool will run fine with either the skimmer alone or the main drain alone, but if I completely close the main drain while vacuuming the pump sounds like a washing machine and the basket is only half full at best.

You can use a standard skimmer plate and just drill 1/2" holes in it until the pump basket stays full.

 

[diggler86]

First, are you filling the hoses with the water from a return before connecting them?

Air isn't being introduced. It's just a lack of water that causes the bubbles and churning. The pump is pumping water out of the basket as fast as it can, but the hose can't provide water to the basket as fast as the pump empties it. The hose adds a lot of restriction to the plumbing.

An adjustable plate allows some water to enter the skimmer directly to keep the pump fed while still pulling enough water through the hose for the vaccum to operate.

My pool will run fine with either the skimmer alone or the main drain alone, but if I completely close the main drain while vacuuming the pump sounds like a washing machine and the basket is only half full at best.

You can use a standard skimmer plate and just drill 1/2" holes in it until the pump basket stays full.

When skimmer mode alone after pool has been running, and I open manual filter valve, water immediately comes out.

When auto cleaner has been running, and open manual filter valve, a good amount of air comes out. So thats why I think there is air getting into the system. Along with the return bubbles. If I remove the head of the cleaner, it seems to suck less air, but I surmise this is less pressure without that yellow mouthpiece operating.

I dont recall the behavior after running manual vac since it wasnt that long a time period. Yes the hoses were filled with water when attaching.

 

[diggler86]

Well I tried a new vacuum, the Pool Cleaner... with the same results. I like it better than the old Zodiac anyway (its quiet!) so figured it wasnt a bad investment and came with new hoses too. Lubed pump o-ring over and over, same results.

So finally I called the leak detection company, they pressure tested the suction side and everything held air fine. They did not find anything wrong with the skimmer either. So the good news is that the skimmer and underground piping seem to be fine.

The bad news is that I still have the phenomenon, where skimmer mode is fine, but when I plug in the auto vacuum i get a good deal of air bubbles coming out the return.

The leak company said that the only possible place left is right before the pump inlet, where the threaded fitting is. They thought when they put some silicon on there they heard some sound of it sucking in. But with the joint covered in silicon now, I still get the bubbles (and I dont see any small bubbles coming in the inlet anymore). Their advise was to replace the PVC between the pump and the copper pipe to the pool. But I wonder if there was a tiny leak, but thats not causing my issue.

Before I go about this, even though PVC is cheap to try it, could there be anything else? Such as something with the impeller? Maybe there is some impeller gasket where air is getting in? It just seems the amount of bubbles Im getting in the return is more than would come from a tiny leak in the suction PVC elbow.

I've also read about the newer variable speed pumps, and so I'm wondering if while I'm redoing this PVC, if it makes sense to upgrade the pump (and hopefully kill this problem in the process - whatever it is). There is a electric company tax credit, etc.. thoughts?

 

[Bama Rambler]

A very tiny leak will let in a lot of air under suction. I would also suspect the pump inlet threaded connection. That's a common place to have a suction side leak.