Sources of Microbubbles

[Yellow Eyes]

I have been having a microubble problem lately, not tons but enough to be annoying, so I was hoping to get some input as to where my microbubbles are coming from.

I have a 40g breeder, 29g sump, with a RO 110SS Skimmer separated from the return pump by a 14 inch tall bubble trap. I also see no microbubbles in the return section, and this skimmer has been broken in for 4 months now.

My return pump is plumbed by flexible hose to a check valve, and then into a bulkhead that has loc-line in the tank. This is all 3/4" hose. I don't see any leaks anywhere so I can't imagine that this is generating any microbubbles. I have also tightened the hose clamps.

I thought I was getting microbubbles from the surface, so I changed some of the powerheads that were pointing at the surface and I still have microbubbles.

After all this I still have microbubbles. Can anyone think of any other sources of microbubbles that I can try and eliminate?

[oneofmany]

I'm not exactly sure where the micro bubbles are coming from, but sometimes when a return pump is not submerged enough a whir pool type of effect will occur causing the pump to draw in some air. Especially if the water level fluctuates in the sump throughout the day.

[1SaltCreep]

I have the exact same setup (diff skimmer), and went through this same thing. I had to use a strong flashlight to see these micro bubbles, but they were there. Found that my top off sensor kept the water level in the return chamber abt an inch below the level of the partition, creating a very small waterfall. After bringing the sensor up a little, there is almost no waterfall into the chamber, and the micro bubbles disappeared. However, if you're sure you don't have the bubbles in your return chamber, this won't help.

Can't imagine how you could acquire micro bubbles between the return pump and the DT output. Any opening that would allow air to enter is going to cause a leak, since the line is under pressure.

[Grayhead]

I am going thru an issue with microbubbles as well. My situation is similar to yours. There are many things that can cause this. I think my issue is between my return line having a sort of cavitation either in the pump or in a union or fittings. My issue is the same in that it's not overly bad, but enough to upset the clarity of the display.
I am taking steps to rule out if it's the pump or the plumbing.
And yes, you can have air drawing into a line without water showing up.

[scooter31707]

Where is your skimmer located? What is your water level for the skimmer?

[1SaltCreep]

Well, the original question is kinda old. Assume the OP has already solved the issue by now. For others, I can only say what worked for me on three tanks, and adjusting top off level is a very easy thing to try.

[Yellow Eyes]

Sorry, while I am a reefer I am also in school and had a busy week. I am starting to think it might be somewhere where I have threaded fittings, so I am going to add a layer of thread tape on the outside of all my threaded connections to see if that fixes it. I will let you know.

Salt creep, I too have about an inch drop from chamber one to two, but the micro bubbles formed would have to travel down 14 inches and back up 14 inches then back down another ~9 to get to the return pump. I may try it though.

[jmm]

If the return pump can pull a vortex from the surface it will pump some air. Put a 90° elbow on the intake pointing down.

[Yellow Eyes]

If the return pump can pull a vortex from the surface it will pump some air. Put a 90° elbow on the intake pointing down.

Again, the pump is submerged in 14" of water, it is not pulling a vortex, neither are my powerheads.