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micro bubbles

T

TheGuyFromNJ

I have a substantial amount of micro bubbles coming through my return into the tank. I am out of ideas on how to stop them. ???

What I have tried:
3 panel bubble trap in sump (under/over/under)
Filter media inside bubble trap
Filter floss inside bubble trap
Filter media and filter floss together in bubble trap
elbow on return pump pointed downward to pull bottom 3/4" of water from sump
made sure the anti-siphon on the return in the overflow is below the water
added filter media on output of skimmer
ran a day w/o the skimmer :eek:

From the mag 9 return pump it is hard pvc until 6" before the bulkhead then it is barb fitted and clamped to silicone tubing. No water is leaking out since the tank (AGA RR 90) was installed 6 months ago. I have had this problem since the tank was installed, but thought everything would break in and the bubbles would stop.


Any suggestions?

Thanks in advance
 
S

stcreef

Do you see bubbles in the return section of the sump? If not then it sounds like the pump might be cavitating. Try putting a "t" in line and a valve and dump some water back into the sump.

Just a side note, I find a over,under,over trap works much better.
 
mikem

mikem

Officer Emeritus
Officer Emeritus
stcreef said:
Sounds like the pump might be cavitating. Try putting a "t" in line and a valve and dump some water back into the sump.
Click to expand...

Either this or your plumbing from the pump to the tank is sucking in air.
 
T

TheGuyFromNJ

Phyl said:
Is the Mag9 in-sump or external?
Click to expand...

In sump

stcreef said:
Do you see bubbles in the return section of the sump? If not then it sounds like the pump might be cavitating. Try putting a "t" in line and a valve and dump some water back into the sump.

Just a side note, I find a over,under,over trap works much better.
Click to expand...

Inertial cavitation might be the cause, I didnt think of that. Is there any other way to stop it other than diverting flow? are different pumps more prone?
 
S

stcreef

If a pump cavitates, it means its inlet or outlet is being restricted. You said you were using hose barbs. They are very restrictive. Their bore is much smaller than the pipe of the same size. What size pipe and how many bends are you using?
 
T

TheGuyFromNJ

stcreef said:
If a pump cavitates, it means its inlet or outlet is being restricted. You said you were using hose barbs. They are very restrictive. Their bore is much smaller than the pipe of the same size. What size pipe and how many bends are you using?
Click to expand...

The return is 3/4" and it goes straight up from the sump to the in-tank outlets. No bends, no 90's, just some pvc and some silicone tube.
 
T

TheGuyFromNJ

do you think if i hard plumbed the pump to the return bulkhead instead of using the barb fitting, this would be enough to stop the cavation?? Has anyone had success stopping cavation in their tank?

I have heard stories of people using mag 12's and 18's on a 90, so what makes my mag 9 do this? Can't be too much pump.
 
W

waynes reef

i agree with the barb thoery, i had the same problem with my skimmer pump pulling air till i hard plumbed the pump instead of using hose and barb, i was getting air in the reaction chamber with the air valve shut off, now its clear water, also cavitation will shorten the life span of an impeller immensly
 
T

TheGuyFromNJ

Sorry it took so long to get back. Life happened.

I hard plumbed the return with a union, valve, and a few 90 elbows and a T and valve to my refugium (one less pump now). No leaks ;D Still no luck, still seeing micro bubbles flow out the return. This mag 9 is only 6 months old, and while I had everything apart I checked the impeller and it still looks new.

Cavitation sounds like an good reason, but I have no clue how to prove this, and stop it.

Still looking for input.
 
S

stcreef

Hmmmmmm.....

You said its a AGA90RR. I assume it came with the return pipe and lineloc. If thats what you are using, check the top of the return stand pipe. They have a small anti siphon hole in them. Make sure while the pumps are running that this hole is submerged.

I would also take a bright light (flashlight) and look in the return section of the sump and look for your bubbles. They are usually not as apparent in the sump as in the tank under bright lights. Look down where the water exits your bubble trap.

Where is your refugium in relation to all this? How does the water get from the fuge to the tank?

Pics would be a big help too......
 
T

TheGuyFromNJ

stcreef said:
Hmmmmmm.....

You said its a AGA90RR. I assume it came with the return pipe and lineloc. If thats what you are using, check the top of the return stand pipe. They have a small anti siphon hole in them. Make sure while the pumps are running that this hole is submerged.

I would also take a bright light (flashlight) and look in the return section of the sump and look for your bubbles. They are usually not as apparent in the sump as in the tank under bright lights. Look down where the water exits your bubble trap.

Where is your refugium in relation to all this? How does the water get from the fuge to the tank?

Pics would be a big help too......
Click to expand...

Yes an AGA90RR. It is using the stock stand pipes. The anti-siphon hole is about 1/2" under water when the pump is running. I am seeing the bubbles in the fuge too. The fuge is a 15 gal display fuge sitting beside the main tank on a standard metal stand, fed from a T off the return pump and gravity drained back to the filter sock.
I am not seeing an excessive amount of micro bubbles in the return section, but if they are getting to the fuge and main tank, then it has to be from the return pump. I do see tons of bubbles in the sump from both the drain and the skimmer. Taking a pic of bubbles is tough. But I can explain the diy 29 gal sump:
Water drains through hard PVC to the far right side 2-3" underwater into a sock, over a baffle then to the skimmer (AquaC Urchin Pro), then 3 more baffles (under/over/under) then to the return pump.

While I am waiting for replies I am going to try to swap out the pump.
 
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