Bubbles in pump basket and PSI drop.

[mtw826]

I have researched my problem thoroughly on this site and have tried everything that everyone suggests and still have not been able to fix my problem. Everything was working normally until about a week ago. All I did last weekend was fill the chlorinator with tabs and vacuum the pool through the skimmer and I use a canister with a netting in it to catch debris while vacuuming. So I noticed the pump had a very slight whispy sound ( the sound you hear when there is air in the pump before it gets to full suction on startup). There appears to be BB sized bubbles flowing around in the pump basket and the same thing coming to the top of the water out of the jets. My PSI was always at 14-15 and now it is at 10-11. Nothing changes with the bubbles when I turn the valve from the skimmer to the floor drain. It acts exactly the same. I have lubed the o rings on the pump basket and the chlorinator, checked for debris where the top screws on to the basket. I also noticed some air in the glass top of my sand filter so I unscrewed that plug in the top while it was running to let the air out of that part. None of this has fixed my problem. The flow at the returns seems normal. I don’t really think that there is anything clogged on my impeller but can’t tell for sure because I can’t see it. It probably isn’t a big deal but it is bothering me because it was working fine last week. There is no leaks in my equipment in the pool house and all my drain plugs are tight. I’m figuring it’s probably something easy considering the way it just started but I’m out of ideas. Anyone have any new ideas for me? Thanks in advance.
Mitch

 

[mas985]

When you start to see tiny bubbles, it usually means that the suction has increased for some reason, usually a suction side blockage of some sort. If you have any suction valves that can be disassembled, you might want to check if anything is caught up in the valve and/or suction lines.

 

[Melt In The Sun]

I agree with mas985 (he's the pro, after all!). Your pool shows the classic symptoms of a suction blockage.

 

[mtw826]

So your saying it would be somewhere near the pump? It happens on both my drain line and Skimmer line when I isolate each. The only thing I can think might have got in there is pine needles. Would those get stuck in the valve?

 

[Melt In The Sun]

Can't hurt to open it up and check, right?

 

[mtw826]

I took the valve apart and there was nothing lodged in it. Although I did figure out that if I turn the valve to the position that allows both the skimmer and floor drain to be fully open the pump goes back to normal and psi goes back to 15. When I close either one I get the bubbles in the basket and psi drops to about 11-12. I am almost positive there is nothing clogging the lines. Is there anything else I could check. The fact that this came on all of a sudden doesn't make any sense. This is a picture of the valve. Right now the valve is letting in full flow from both lines, main drain on the right and skimmer on left. Going into the pump is the pipe going up.

 

[mas985]

Are you sure that wasn't the setting you had on the valve before? When you close off one or the other line, that will increase the suction as well and could cause the bubbles. I would suggest that you have both open most of the time anyway unless using a cleaner.

 

[Melt In The Sun]

Ironically, I just fixed a very similar problem on my own pump yesterday. I had BB-size bubbles as you describe, and had already changed the gasket, cleaned out the valve, etc.

I had a tiny leak on the underside of the threaded connection on the inlet side of the pump. I found it by running a hose over the connection and cupping my hand around the bottom of the pipe, and leaving it there for about 30 seconds!! That turned out the be key, since it took that long for the bubbles already in the basket to get pumped out. The first time I tried to find the leak (a couple months ago), I just ran water on the tops of the joints for a couple seconds, then gave up.

I cleaned out the gunk on the threads with a wire brush, washed it off, and put a nice big bead of silicone caulk on it (not sure if this is really how to fix it, but it's what I had ). No more bubbles.

 

[mtw826]

Mark- Thank you for the input. I am positive that I didn't have the valve here before. I have never done it like that but never really knew where it should be. I will leave it there unless I am vacuuming from now on. So how do those bubbles form from an increase in suction?

Melt- Thank you as well, I will check out your idea too but you would think if that was the case the bubbles would be present in all positions and not go away when I have both lines fully open right.

Thanks a lot for your help. I just found this site a couple weeks ago and I am learning so much. It is a great resource.

 

[mas985]

There are two sources of bubbles that end up in the pump basket. First, if there is a leak as Melt suggested, the pump will draw in air creating the bubbles. Higher suction means more air and larger bubbles. However, you should still see some with the valve in the middle.

Second, even if there is no air leak, dissolved air can be drawn out of the water if the suction is high enough. Normally, there is a fair amount of dissolved air (primarily oxygen and nitrogen) in water so if the water temperature rises or the pressure drops, air will start to come out of solution. This is not unlike leaving a glass of cold water in the sun and seeing the bubbles form on the inside of the glass.

So the first can be solved by finding the air leak and sealing it. The second can only be solved by reducing the suction. But in either case, the air is really not that much of a problem unless it starts to fill up the pump basket because the pump cannot get rid of it fast enough.