Micro Bubbles from closed loop

[krisfal]

Being tired of constantly having to mess with powerheads falling off the sides/back of the tank, I recently built an over the top closed loop system for my 130gal reef. It is powered by a Danner Model 24 Mag drive pump. I originally put it together with 2" PVC after a mis-communication with my husband when I asked him if 2" PVC was 1 1/2"ID (the minimum recommended size for maximum flow given in the pumps instructions).

When I started it up and for several days I had tons of microbubbles. A good friend and fellow reefer felt the problem was the pipe size. Due to limited time before leaving on vacation I replaced only the intake size with 1 1/2" PVC. This has reduced (about 80% reduction), but not completely eliminated the micro bubble problem.

Before I tear this apart and replace the output size with 1 1/2" PVC I would like to hear from others regarding this problem. I would like to know if anybody has any other ideas or thoughts on things I should consider. Taking this system out and switching out the parts is going to be more work than it was to originally put it together. Therfore, I would like to be fairly confident that I address all possible causes of the microbubble problem at that time.

Thank you in advance for your ideas and thoughts!

 

[krisfal]

Been doing some searching on old threads trying to find an answer to my problem.

I found one thread that talked about locline being above the water could cause this problem, causing a venturi effect. But not everyone agreed with that theory. My locline is partially above water. Has anyone ever found this to be a factor in problems with microbubbles?

In another thread an opinion was stated that have a larger outlet than inlet should not be a problem other than possibly increasing head loss because the pump is having to push a larger volume of water. Any opinions on this opinion? I would sure like to not tear this apart and replace the outlet side if it is not going to do anything for the microbubble problem.

One of these two threads also suggested tightening the end cap that is used to prime the system, I know I did not put a wrench on that, so I am going to go give that a try now.

Any other thoughts if tightening the cap doesn't work? This is driving me nuts.

 

[krisfal]

Tightening the cap did not help.

 

[reefindad]

Just a thought, but maybe going over all of your connections with glue to insure zero possibility of a very minute break in the seals?

 

[acrodesiac]

If you had less than 500 gph going throgh the loc line I would say it's not the cause. But it sounds like you have way more flow going through it, I would start with the unsubmerged loc line before ripping it all apart. Good luck Kris

 

[ReefferMan]

I think its due to the pipe size. A mag 24 has a 1' in and out rite? I may be wrong but there might be places in the pluming that are holding air. Try priming it again? did you use teflon tape on the cap? Put more? Hmmm

http://www.futurepets.com/cgi-bin/fullpres.exe?PARTNUM=EUD2522

 

[krisfal]

Thanks for the suggestions everybody. I am still fighting the problem as I have been out of town off and on all month so have not had much time to work on this. The only reason I set it up before leaving on vacation was due to my suction cups on the powerheads getting so old that the PHs were constantly falling off and I did not want my tank sitter to have to deal with that problem.

As suggested above I am going to add another layer of PVC glue to all of the joints. I have also bought the parts to modify the output side so all of the locline will be submerged. I hope to be able to get those task done this week/weekend.

ReeferMan-The instructions that came with the pump said minimum 1 1/2" pipe. I initially used 2" but have replaced the intake side only with 1 1/2". I have reprimed the system at least 3 times as I do modifications. I have checked and rechecked all of the threaded fittings and yes I used teflon tape (lots and lots as I have pulled apart the threaded joints and removed and replaced the teflon tape to ensure these were not my problem).

Hopefully the steps I outlined above will resolve this problem once and for all, if not I will likely go ahead and replace the output side with 1 1/2" pipe. Maybe I can get a job as a plumber when I am done with this project

 

[krisfal]

I added another layer of PVC glue to all of the joints. I also modified the output side so all of the locline is submerged and still have microbubbles :evil:.
Nothing left to try except going down to 1 1/2" pipe on the outlet side

I did take the pump apart and found one of the shafts on the impeller had partially shattered:shock:, did some repair and the pump is quieter than it has ever been. Wish I had found that a lot earlier when I could have returned the pump, this pump has been noisy since the fiurst time I plugged it in so I suspect it came with that problem. I'll be ordering new parts, but I was able to grind out the rough spots on everything and get the system up and running. But the little pieces I found in there, that broke of from the shaft, definately explain the noise I was getting.

And here I thought a closed loop would be less trouble than the PHs falling of the side all the time, lol

 

[ecobalance]

Try a t inline with a bleeder

I would put a t inline with a good gate valve[not ball valve]faceing upwards on the plumbing.

 

[krisfal]

I would put a t inline with a good gate valve[not ball valve]faceing upwards on the plumbing.

ecobalance could you provide some more info? Maybe a diagram? Are you talking about the intake or the output side? I am thinking you may be referring to a way to bleed the air from the system?? My dad has said he thinks that is what I need to do.

Thanks

 

[Krish]

When I did my over the tank closed loop, I had micro bubbles. I was told it would take some time for the plumbing to slime up a bit which should stop it, but I tore it down before giving it a chance. So I did another over the top closed loop and had micro-bubbles for maybe 5 mins or so and then it stopped. Sometimes air gets trapped in the plumbing which causes it. You sometimes have to turn off the pump and restart it a few times to get all of the air out. I'll post a link to my old thread where I did my closed loop icase something there may help

Good luck and I'll fetch that thread

 

[Krish]

Here you go...Alot of crazy posts in there but if you scan through to the pics, you can see how I went about it. Hope it can be of some help

http://www.reeffrontiers.com/forums/showthread.php?t=13588

 

[ecobalance]

Like brake calipers

I've got to be honest with you Krisfal,i've never done one[a closed loop that is]But have helped some one trouble shoot one.Oor last ditch effort was to put a t in-line,on the output side after the first 90.It faced upward and throtled down from 1 inch to half,this is where we put the gate valve with a tube running back to the sump.This worked well[temporaraly],and in some cases for even a couple days.The problem was any time a vortex was created,or a power head belched out some air, the bubbles re-apeared.Why was there power heads in the tank,with a closed loop?Not my tank,and too much time on this persons hands,would be my best answer to that.I wish i could help you but the truth is ,there are more than a few things that could be causing this,such as loose ,or vibrateing fittings,a bad pump seal,a faulty manafold,etc.The t and gate will release any air trapped in instalation,and if they don't come back than that was your problem.If they do than it lies somewhere else,but you still have the bleeder for a quick fix.How long this fix will hold depends on too too many things.Makes me yawn just thinking about it lol hope this helps a little. O and by the way,i just got a 400 gallon L shaped glass aquarium that i ordered drilled for a close loop.So if you here a huge [glass breaking sound]out to the north;you'll know i lost the battle,but won the war.

 

[ecobalance]

and actually

I'm already comming up with a back up plan after seeing the aquarium where i will use the too holes drilled in the bottom as a surge devise,with live rock drilled and placed over the pipes,and with the four holes across the back will be filled with jacuizi style jets that will be the returns for the over flow that is drilled for a 3 inch drain.The first and biggest hurdle is how the he-- im going to get it throuh the guy who ordered it,s door?1400 pounds empty.The L is 6 ft by 5 ft and is 28 inches wide and 35 inches high.Aquarium insanity at it's finest.

 

[Scooterman]

I found one thread that talked about locline being above the water could cause this problem, causing a venturi effect. But not everyone agreed with that theory. My locline is partially above water. Has anyone ever found this to be a factor in problems with microbubbles?

It can be a problem but if your talking a short distance from an outlet to the inside of the tank It shouldn't be a problem.

In another thread an opinion was stated that have a larger outlet than inlet should not be a problem other than possibly increasing head loss because the pump is having to push a larger volume of water.

There will be no additional head loss If anything you will get a reduction of head, this should not be a problem at all, I built a 2" over the top before with absolutely no issues with going oversize inlet & outlet but it must be done right.

One of these two threads also suggested tightening the end cap that is used to prime the system, I know I did not put a wrench on that, so I am going to go give that a try now.

Use Teflon tape on all threaded fittings, this should be tight enough to keep air from sucking in.
It can be difficult to troubleshoot another's tank like this because the slightest oversight can lead to the problem, Pictures would help maybe but best thing is to check every connection, pump connections, all of it top to bottom. If necessary you can add PVC glue to the connections throughly to see it you can maybe get the spot that is sucking in air. Also make sure the inlet is deep enough in water as this can also lead to air in the system.

 

[krisfal]

Thanks everybody for the input.

Krish the thread on your CL is one of many I read before attempting this project It was definitely helpful.

The L is 6 ft by 5 ft and is 28 inches wide and 35 inches high.Aquarium insanity at it's finest.

lol, yeah I have been thinking about an 8ft glass tank

There will be no additional head loss If anything you will get a reduction of head, this should not be a problem at all, I built a 2" over the top before with absolutely no issues with going oversize inlet & outlet but it must be done right.

Thanks for that info. I keep thinking my issue has to be on the intake side. I have been resisting replacing the output side, it’s a lot of work to end up with the same problem (but I guess I have been doing a lot of that already)

Use Teflon tape on all threaded fittings, this should be tight enough to keep air from sucking in.
It can be difficult to troubleshoot another's tank like this because the slightest oversight can lead to the problem, Pictures would help maybe but best thing is to check every connection, pump connections, all of it top to bottom. If necessary you can add PVC glue to the connections throughly to see it you can maybe get the spot that is sucking in air. Also make sure the inlet is deep enough in water as this can also lead to air in the system.

I have added additional PVC glue to all of the joints on the intake side. I used teflon tape on all the threaded fittings, wrapped correctly. Most of the threaded fittings have been pulled apart, cleaned off, re-wrapped with teflon and tightened. The inlet is aprox. 8 inches down in the tank, I do not think it is pulling in air, I even turned the locline spout away to be sure the air was not just being re-circulated by the system. I just keep thinking . . .what is it I have not checked yet

I could try to get pictures but because it is mostly in the small space between the tank and the wall I don’t think it would help. It is a pretty straightforward system with minimal plumbing and as you said it is difficult to troubleshoot something like this from afar. I mainly am looking for tips or tricks, something I have not tried that might do the trick (heck a miracle would be nice). However your post has me thinking about the pump seal itself. I have had the pump apart and looked at the o-ring but I think I am going to take a closer look. thanks alot for your input

 

[moortim]

How far is the intake to the pump from where the drains from your tank are located? It should be a foot or less if possible, what is probably happening is that the pump is cavitating. I am no expert on this but have been instructed by an expert on how to avoid the same problems you are facing. Because of the pressure on the intake the impeller of your pump is basically beating the dissolved air out of the water as it passes through causing the air to form bubbles. I have a similar closed loop with 1 1/2 in pipe where the pump is very close to the outlets from the tank and have no problems with bubbles.
I hope this is all clear, some of it is my understanding of what someone else recently taught me but it worked for me.

Tim

 

[Scooterman]

You can submerse parts under water until the micro bubbles are gone, get some help, use ro/di & use some plastic over the joints & try to soak each one, start around the pump. Usually in this situation the simplest thing is the cause & it is right in front of you, also submerge the loc-line deep enough just to make sure. It may be messy but you might just get lucky & find it.

 

[krisfal]

Pictures

Moortim-It is about 14-15 inches from the output on the pump to the first T that is the start of the first outlet into the tank. I had read about cavitation but was under the impression it would take a lot stronger pump

Here are some pictures. Note the small PVC (1/2") is the rack that holds up the pump/closed loop plumbing. In order: a picture of intake and left side of output from top of tank, 2nd picture is the left side outlets (matching pair are on right side), last picture is of the intake from the side of the tank.

I think from the picture you can get a good idea of the intake, the outlets are all in line with 2 at each end of the tank.

Thanks once again for all the input.

P.S. Scooterman-that sounds like a mess I will have to ponder that one, I am too much girl to intentionally make a big mess in my living room. But maybe I can set this up on a tank I have empty now and give your idea a shot outside.

 

[krisfal]

Update

I replaced the entire 2" output on my closed loop with 1 1/2" yesterday. There is a noticeable reduction in the microbubbles, although not completely gone. Although, I now suspect the pump cover that I cracked is likely the issue. I have patched the crack in the threaded area by gluing in the threaded fitting and wrapping the area with epoxy, but I plan to replace the pump cover soon as I am not confident about the patch job.

The good news is I took this opportunity to redesign the output to spread out the nozzles to 4 corners of the tank. I love the results! I feel my flow pattern is much more effective than before!