help keeping bubbles out of U-tubes

[redfishsc]

Howdy all,

I have a bit of a unique system (aka, ghetto). The description is below, but the main problem is I am getting air pockets trapped in my U-tubes that connect 4 small tanks together. I can't seem to get the flow right to wash them out (either too much and causes a flood, or too little and the air gets trapped).

My main display tank is a 25g tall, with a 20g-long frag tank, a 5.5g refugium, and a 5g sump (custom built to fit in its place).

All four of the tanks are connected together by U-tubes (the tops of all of them are even). No overflows or holes drilled or anything like that. Water flows from right tank (sump/skimmer) to left (main tank) and back.



I'll try to get a pic if you need one when the lights are back on for it to make sense but it's pretty simple.


Anyhow, my problem is the U-tubes I am using are collecting a lot of air in them. Once a week I have to stick some flex tubing up inside them to slurp out the air bubble. I think it's mostly due to algae growing in them, as they all get a lot of light from the light systems (particularly near the frag tank).

Normally the air doesn't slow down the water flow, but I keep the bubbles managed. I'm afraid if I were out of town for a couple weeks, I'd have a problem.


I really don't want to spend the money on an Aqualifter pump for all 3 U-tubes. I'm hoping someone has a very cheap and easy fix for this.

I tried increasing the water flow so the bubbles would wash out, but found that an extra MJ900 added way too much flow.


I dunno. Any thoughts/suggestions?

 

[iamwrasseman]

if you drill an eighth in hole on the top of them and hook a vacume line off from a powerhead to each one the powerhead will evacuate the air constantly and they will provide circulation in your tanks at the same time .you will have to buy a stainless steel nipple for each one and seal it up well as a leak would be a bad thing .

 

[coral_lagoon]

^ What he said.

When I had my U-tube box. I used a plastic nipple, and glued it with some pvc glue..

 

[coral_lagoon]

Re: help keeping bubbles out of U-tubes

<a href=showthread.php?s=&postid=15507953#post15507953 target=_blank>Originally posted</a> by redfishsc




Anyhow, my problem is the U-tubes I am using are collecting a lot of air in them. Once a week I have to stick some flex tubing up inside them to slurp out the air bubble. I think it's mostly due to algae growing in them, as they all get a lot of light from the light systems (particularly near the frag tank).

Thats ONE of the reasons why I switched to a CPR overflow box..

 

[Skunkbudfour20]

Simple solution, paint them black so light doesnt get in and it will slow algae growth i used 1/2" masking tape on the inner side so i have a window to check them for debris and painted the top black...

Secondly upping the flow through your overflow helps to remove bubbles, if you are running low amounts through the bubbles just stick...

If your tanks are smaller and upping the flow isnt possible, then i would use whats mentioned above and use a piece of airline tubing and an aqua lifter dosing pump, or just put it in the air inlet for a MJ or smaller powerhead (one in each tank)

Best solution, have the tanks drilled and connect them directly

 

[Toddrtrex]

Drilling/putting a hole in a U-tube will defeat the purpose of having a U-tube. IMO, that would be a very poor idea and cause more issues.

A picture would help. But, from what I understand all the tanks are on the same level? This part made me think that "(the tops of all of them are even)." If that is the case you are going to have issue with any HOB overflow, with them being at the same level there is no gravity affecting, which makes an overflow work.

 

[iamwrasseman]

um you put negative pressure on the nipple and it cleares all bubbles not thus regucing issues .the poweerhead pulls air in with its vortex action and it creates a siphon ,that removes all the bubbles 24/7/365

 

[redfishsc]

Agreed, wrasseman, I've seen that before and thought about it.

I do have a MJ in each tank for circulation, so I'll rig them up with something like that. Thanks for the help!

 

[Newreeflady]

Bubbles seemed to build for me when flow was insufficient. I'd think smaller tube or more flow, but that's just me. The more complicated stuff you add to it, the more there is to go wrong.

 

[redfishsc]

<a href=showthread.php?s=&postid=15509213#post15509213 target=_blank>Originally posted</a> by Newreeflady
The more complicated stuff you add to it, the more there is to go wrong.

That's about my life philosophy. Simplicity is the key to most things in reefing, so I've noticed.

 

[iamwrasseman]

yup keep it simple stupid is my saying to that one

 

[redfishsc]

I'm starting to wonder if I could drive all 3 of them with a single Aqualifter or maxijet---- using connecter T's to T them all into the same pump.

It doesn't take much suction to draw the air out..... hmmmm.....

 

[Ebisan]

I cover my u-tube with aluminum foil.

 

[Newreeflady]

<a href=showthread.php?s=&postid=15512476#post15512476 target=_blank>Originally posted</a> by redfishsc
I'm starting to wonder if I could drive all 3 of them with a single Aqualifter or maxijet---- using connecter T's to T them all into the same pump.

It doesn't take much suction to draw the air out..... hmmmm.....

the point is that if the flow is sufficient for the tube diameter you shouldn't have any air bubbles building up. Get a better overflow if you do.

 

[redfishsc]

newreeflady, I am unable to get a fast flow going through these tubes because there isn't sufficient gravity between the tanks to pull a fast flow.


The reason an overflow can handle a fast flow rate is that the hoses or PVC drops way down to the sump, meaning, it falls a lot further, faster, and harder.


These tubes are all connecting tanks that are even with each other, so there isn't much "headway" to allow the tubes to suck a higher flow.

Trust me, I've tried and failed! If I had not been watching VERY closely I would have emptied a lot of water on my carpet, lol.

 

[atxryan]

the levels do not matter. it is the velocity of the water that carries the bubbles out.. Since you cant increase the flow, you need to decrease the diameter of the U tube. I would try running a flexible tube inside your U tube. This will help increase the velocity inside the tube without changing anything else. I would use a tube with thick walls and an outside diameter just slightly smaller than the tube. Every siphon flood I have ever heard used U tubes with holes at the top..As always, Keep it simple. It is a physics issue and should not be over-engineered.

 

[iamwrasseman]

atxryan has a good point ,simplicity is the key . when i did the three tank hookup with u tubes back in the day i had a 46 gal bowfront and two 20 gal highs one on each side but they were 2 1/2"lower than the 46 bow so they flowed well and i never had a problem but your tanks are even at the top ,correct ? if so you will need to use smaller tubes and get the flow correct as atxryan is explaining . yes you can drill and use nipples with the powerhead suction and it will work fine until one of the powerheads stops running then you could have an overflow . i also did it with the powerheads for three years or so and never had a problem , maybe i was lucky but it did work . both ways will work but without the powerheads you may get the bubbles building up unless you can increase flow .and with them you then depend on them working 24/7/365 , confusing huh ?pick one way and do your best i say , and most of all good luck !

 

[redfishsc]

<a href=showthread.php?s=&postid=15520245#post15520245 target=_blank>Originally posted</a> by atxryan
the levels do not matter. it is the velocity of the water that carries the bubbles out.. Since you cant increase the flow, you need to decrease the diameter of the U tube.

<a href=showthread.php?s=&postid=15508526#post15508526 target=_blank>Originally posted</a> by Toddrtrex
But, from what I understand all the tanks are on the same level? This part made me think that "(the tops of all of them are even)." If that is the case you are going to have issue with any HOB overflow, with them being at the same level there is no gravity affecting, which makes an overflow work.

I think Toddrtrex is right here, though.


I remember when I lived in a house years ago that had a very tall crawlspace, I could siphon water out of the tank about 100X (exaggerating) faster by tossing the other end of the hose out the window and letting it siphon out on the ground (freshwater tank) VS. just letting it siphon into a bucket at my feet.

I think this is the same principle as to why I can't get more flow through these tubes. There isn't a height difference between the tanks which is preventing the siphon effect from generating a "pull" using the acceleration force of gravity.


I fear that your suggestion of reducing the diameter of the tubes might cause the same problem--- too much flow for the tube diameter....(not to mention potential turbo/astrea snail blockage... they already travel tank to tank through them).

Right now the tank seems to be flowing at about the max flow rate that the tube diameter can handle.




I am starting to think the answer may be a comb/mod of these two ideas.


Instead of drilling the top, why not just run some rigid, thin airline tubing up through one side of it, so that the end of the tubing touches the top of the tube. The other end of the rigid tubing takes some flex tubing to a pump. No holes in the tops, minimal obstruction of the tubes. I dunno... maybe it'll work...?

 

[iamwrasseman]

yes the more water weight the faster the flow