Air Bubbles Coming from Return After Sand Filter Bleed

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
I was messing around with my sand filter and opened the bleed valve. No real reason just messing with things. Well now that I've done this I have a ton of air coming out of my returns. Help...lol
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
11,084
Houston, Texas
Is the air bleed open while the pump is running? You may need to do that to let out any trapped air.
 

solarboy

Well-known member
Aug 1, 2010
337
Europe
I've seen this before. I think it's large bubbles of air caught in the turbulance in the filter and pump that gradually disperse. Sometimes just turning the pump off and waiting a few minutes helps, or turning the pump off and bleeding the filter.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
zea3 touched on this but for a in ground pool where the filter is above the water line, when you open the bleed valve with the pump OFF, air will get sucked into the filter. The weight of the water pulls in the air. So when the pump is turned back on, the air will be purged out of the filter through the returns. To bleed air from the filter through the bleed valve, the pump must be ON.
 

solarboy

Well-known member
Aug 1, 2010
337
Europe
Is the pump below the water line then? I have had below the water line filters that have bled better with the pump off. I've similarly primed pumps by turning them on then off again when pockets of air have been trapped and simply running the pump was insufficient.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
The OPs pool is an in-ground and most of the time the equipment is above the water line so air will be sucked in when the valve is opened with the pump off. However, for above grounds and a few in-grounds where the water line is above the filter, you can purge the air with the pump off.
 

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
Water line is below the filter. Right on. Even leaving the bleed valve opened with the pump running though didn't seem to rid the system of air. Just gradually went away as I let the pump run.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
If you keep getting air into the filter when the pump is shut OFF (listen for the air bubbles in the filter), then it could be a gasket leak in the backwash valve that only lets in air but does not let out water when the pump is running.
 

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
I commonly hear what sounds like air in the filter. I've been concerned with my gasket because one time (yes I seem to like to make the mistake first and then learn) I moved the valve when the pump was on. Any other way to verify this may be faulty?
 

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
Nevermind....I misread your post. It's when the pump is running. Maybe sounds like air...maybe like water flowing quickly through the valve.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
When the pump is running, air would not enter through the filter but it could on the suction side. Do you see bubbles in the pump basket?
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
The pump is probably sucking in air and passing it through to the filter although this should be fairly constant and not diminish over time.

Do you have all of the valves open for the skimmers and main drain?

A quick fix for the oversized pump problem would be to swap out the impeller for a smaller one. I replaced my impeller for a 1 HP Northstar down to a 1/2 HP version and cut my power consumption nearly in half.
 

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
All valves are fully open to both skimmer and the main drain. The noise is consistent. Air bubbles at the returns is minimal. What I was commenting towards at the start of this thread was a much higher rate of bubbles in the return flow. That has since diminished since the pump has been running. The constant flow of very light bubbles is still there. I would swap out my impeller but I'm still a bit concerned that I will lose too much flow to provide enough pressure to my mist cooler and to my spa jet returns when being used.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
It looks like you have a second pump for the spa, no? And I would suspect the misters don't require much in the way of flow rate.

Also, the small bubbles are probably due to the SWG.
 

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
They actually ran the second pump for the waterfall feature. The misters do have to overcome a good bit of head pressure as they rise out of the water about 1 foot before the water comes out in a mist. I actually have to block off two returns to get adequate flow out of the misters.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,424
Pleasanton, CA
Then in that case, a two speed motor might be the ticket. You can run on low for circulation and high when you need it.
 

eric99gt

LifeTime Supporter
Sep 14, 2009
174
Houston, TX
I've thought that may be the solution but I'm concerned I would just always be running it on high anyways (at least in the summer when I use the mist coolers which can last nearly 6 months in Houston). There's a few different scenarios for myself where the requirements for flow would be different
1. Most common: Pump running in pool mode with with spa spillover, misters in place, some flow returning to spa to circulate.
2. Pump running in pool mode with spa spillover, no misters, some flow returning to spa to circulate
3. Pump running in spa mode, all water to spa
4. In either of the first two cases my pool cleaner could be running as well. I'm not sure this matters as it runs off the booster pump.

I'm kind of stuck between having a pump that's over sized for my piping (1.5 inch) which seems to be causing a very turbulent environment in my pump strainer basket and not to mention the cost, or the other scenario of purchasing a smaller pump and possibly running in to not having enough head to properly operate the misters (which I love because it's so Dang hot here anyways lol)
 
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