Trouble with micro bubbles

[luxauterna]

Hey everyone. I am running into an issue with micro bubbles in my new build. I am thinking that it is related to my Mag 18 return pump. I have checked all the plumbing (hard plumbed) and I am not having any leaks and they seem solid with the seals. So I don't think there is air getting drawn in. It is also a very short distance of plumbing from the pump to the first return nozzle.

I can actually hear when the micro bubbles are going to be discharged. It sounds like the pump makes a different noise and then I see them. Does this sound like an issue with the pump? Have any of you run into this issue with return pumps, specifically Mag drives?

Thanks!
Ryan

 

[cloak]

Sometimes when the intake of the return pump is too close to the waters edge it will create a whirpool type of effect and draw in some air. If you've got the time, stare at that pump for about 15 minutes or so & see what happens. (slurping sound)

Micro bubbles are not really a problem btw. I kind of dig them to tell you the truth. GL.

 

[AZDesertRat]

How deep is the pumps suction submerged and how do you have things plumbed on both the suction and discharge sides? Any valves, 90 degee elbows or other restrictions on either side? What size plumbing did you use

 

[luxauterna]

The pump intake depth fluctuates with evaporation, but the water level is typically 3-4 inches above the intake. It is plumbed with 3 elbows and 1 ball valve prior to the return ports. The plumbing is 3/4".

 

[AZDesertRat]

Is there are plumbing or sponge filters on the pump suction? Have you tried valving down the discharge to see if the microbubbles go away?
How long has the tank been set up? I have had microbubble issues with new reef set ups more than once but once the system starts aging and becoming "seasoned" the bubbles went away on their own.

 

[luxauterna]

Is there are plumbing or sponge filters on the pump suction? Have you tried valving down the discharge to see if the microbubbles go away?
How long has the tank been set up? I have had microbubble issues with new reef set ups more than once but once the system starts aging and becoming "seasoned" the bubbles went away on their own.

Yes the Mag 18 has a sponge filter prior to the intake. I have tried slowing down the water flow with the valve, but still see a lot of micro bubbles. It has only been filled for a week. I also have run into the situation where the bubbles have died down after a good film gets on the plumbing, but I haven't seen this many bubbles at the start up of a tank before. Also, I don't want to have a build up in the plumbing be the reason for no bubbles, because that just leads me to believe I am not actually solving a possible problem with the pump or plumbing. Does that make any sense? I am hoping that they die down since they cause a cloudy-like look near the center of the tank

Thanks for the help!

 

[AZDesertRat]

3/4" plumbing is pretty small for a Mag 18, thats a big pump. Mag always recommends you step up one size larger than the pumps outlet to reduce the velocity and headloss in the plumbing. I would also recommend eliminating the suction side filter.

I browsed your build thread and it brought up a couple questions. Could some of your problem be related to the protein skimmer? Have you tried shutting it off for 30-45 minutes to see if it may be bubbles carried over your sump baffles? How much water does your return section hold? Again the Mag 18 is a very big pump and you may not have enough retention time in the last section to eliminate bubbles with its GPH. You have a 35G sump and the usable volume when operating is probably 1/2 to 2/3 so say 16 to 20 gallons in the sump. Your return head is probably between 4 and 5 feet so the Mag 18 is doing somewhere around 1100-1150 GPH. Your retention time in the sump is around 50-55 seconds at best which may not be enough time to fully off gas microbubbles from both the overflow and the skimmer. Just some ideas or things to think about. One way to tell if microbubbles are making it through the sump chambers is to shine a flashlight through the sump front to back or side to side. If it looks like diamonds sparkling in the water then you have bubbles. You might try that with and without the skimmer operating and with the Mag fully open and then with it throttled down to reduce the velocity.

 

[luxauterna]

Thanks a lot for all the help and taking a look at the build to get a better idea. I did not know that Mag recommends increasing the plumbing above the outlet size. Thanks for that info! I will try eliminated the sponge filter, but I actually thought that would help with air bubbles. The protein skimmer has not been running while the tank cycles. I will definitely try without the filter and see if it helps at all. The strange thing (or maybe it isn't strange at all) is that the amount of bubbles fluctuate and I notice more come out when I hear a certain noise come from the pump. It is kind of difficult to describe the noise, but it just sounds rough. The distance of plumbing from the pump to the first return outlet into the tank is just under 4ft which matches up to what you are describing. I will give it some time too and watch it.