Are overflow boxes reliable?

Water Dog

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I just now understand what you are saying. Holy bad directions!! If only I had understood this before. I think you are 100% right. I am heading downstairs now to pull that fool sponge off. Me thinks that will end the problem, but the siphon loses siphon everyday now so if that's not the issue I will be able to report back tomorrow AM. Fortunately my sump room is in an unfinished part of the basement so flooding is not really a problem not to mention that I always have 150 gallons of spare sea water on hand for just such emergencies AND the return pump on the refugium is in the top 1/3 of my sump so even if it overflows the 'fuge the main circ and skimmer stay running with the remaining water in the sump.

IMG_0584.JPG

One other thing I forgot to mention in my previous reply... the reason it “seems“ like it’s losing its siphon is that as the exterior box floods, the water level in it rises above the level of the water in your refugium tank, thus the siphon is no longer draining through gravity. Remove that sponge and I’m very confident that it will work as designed, though a bit on the noisier side.
 
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gizzo12

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One of the other things that the sponge is there for is to muffle the gurging noises from water going down the single tube drain. In your situation, noise mitigation shouldn’t be an issue since it’s a basement sump/refugium set up. The Stockman standpipe serves the purpose of noise mitigation well without the potential for flooding. I’ve heeard it mentioned a couple of times in this thread already where some people are restricting the single drain with a valve to cut down on noise... NEVER ever do that. In a single drain situation, that is a bad idea! In any event, please report back. I’m pretty confident that removing that prefilter sponge will fix your flooding issues. Good luck! :)
So in my case, I shouldn’t use a gate valve or anything correct? I got the tunze pump you recommended used. That should be able to control the flow right?
 

Water Dog

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So in my case, I shouldn’t use a gate valve or anything correct? I got the tunze pump you recommended used. That should be able to control the flow right?

A valve is fine for the return line from your pump back up to the tank, even if you’re using a DC pump. What I always caution against is using a valve on the single drain line from the HOB overflow down to the sump. NEVER restrict in any way, a single drain set up.
 
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gizzo12

gizzo12

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A valve is fine for the return line from your pump back up to the tank, even if you’re using a DC pump. What I always caution against is using a valve on the single drain line from the HOB overflow down to the sump. NEVER restrict in any way, a single drain set up.
How can I use a valve with soft plumbing? Just insert it in at any point between the pump and the the j tube?
 

Water Dog

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How can I use a valve with soft plumbing? Just insert it in at any point between the pump and the the j tube?

Yup, that’ll work. For visual reference, here you can see the 3/4” Two Little Fishies ball valve that I use on my return line, from my pump backup to the tank...

D07B8A19-DD16-4B8D-9721-E401E783B9B3.jpeg


And yes, I just wanted to note that I do have valves on my drain plumbing from my overflowdown to my sump... and that is because I am running a dual drain Herbie set up, not a single drain HOB.
 
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gizzo12

gizzo12

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Yup, that’ll work. For visual reference, here you can see the 3/4” Two Little Fishies ball valve that I use on my return line, from my pump backup to the tank...

D07B8A19-DD16-4B8D-9721-E401E783B9B3.jpeg


And yes, I just wanted to note that I do have valves on my drain plumbing from my overflowdown to my sump... and that is because I am running a dual drain Herbie set up, not a single drain HOB.
Looks good thanks!
 

sghera64

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I have had my DIY overflow box in place for over 20 years no problem. Made from acrylic I glued together. Two separate PVC pipes siphon the water out and down to the sump. I recently added a second sump box as a refugium. The refugium siphons to the main sump via an overflow box. They are not pretty. They take up more space, but they seem to work.
 

2Sunny

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One other thing I forgot to mention in my previous reply... the reason it “seems“ like it’s losing its siphon is that as the exterior box floods, the water level in it rises above the level of the water in your refugium tank, thus the siphon is no longer draining through gravity. Remove that sponge and I’m very confident that it will work as designed, though a bit on the noisier side.


Checked this morning and of course the siphon is working perfectly. Why would eShopp put a pipe and sponge at a height just high enough to make the siphon fail?? I DuckDuckGo'd the issue a dozen times finding guesses of "flow" "air" "tilted box" etc. but no where did I find a discussion of the external sponge as the issue. Of course, now that I simply look at it, I'm ashamed I didn't realize what was happening before. It makes perfect sense. I do have to laugh because I finally ran into you, the one person who could solve my issue, a day after I ordered a new tank. Ah, well c'est la vie ;Facepalm Good news is I don't have to switch tanks now and can leave the set up I have alone and sell the nice Glass Cages Refugium.

Anyways, thanks for solving my problem, and folks I'm hear as a convert now. External overflows can be bullet proof - if you know what you're doing.
 

Water Dog

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Checked this morning and of course the siphon is working perfectly. Why would eShopp put a pipe and sponge at a height just high enough to make the siphon fail?? I DuckDuckGo'd the issue a dozen times finding guesses of "flow" "air" "tilted box" etc. but no where did I find a discussion of the external sponge as the issue. Of course, now that I simply look at it, I'm ashamed I didn't realize what was happening before. It makes perfect sense. I do have to laugh because I finally ran into you, the one person who could solve my issue, a day after I ordered a new tank. Ah, well c'est la vie ;Facepalm Good news is I don't have to switch tanks now and can leave the set up I have alone and sell the nice Glass Cages Refugium.

Anyways, thanks for solving my problem, and folks I'm hear as a convert now. External overflows can be bullet proof - if you know what you're doing.

That’s awesome to hear that it’s running properly now. Glad I could help! :)
 
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Borg

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Speaking about overflow boxes..
I’m going to set up a 40B for a qt. 20 gallon long sump.

I’m thinking about drilling 2 holes for 1” bulkheads. 2- 1/2” returns

Or

Just buy a eshopps eclipse (m) overflow box with two 1/2” returns

Can’t make my mind up. Planning on using a ecotech s1 pump (1400 gph)

Both overflows will be installed in the center of the 40b

Like to hear your suggestions
 

Water Dog

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Speaking about overflow boxes..
I’m going to set up a 40B for a qt. 20 gallon long sump.

I’m thinking about drilling 2 holes for 1” bulkheads. 2- 1/2” returns

Or

Just buy a eshopps eclipse (m) overflow box with two 1/2” returns

Can’t make my mind up. Planning on using a ecotech s1 pump (1400 gph)

Both overflows will be installed in the center of the 40b

Like to hear your suggestions


If you’re gonna drill your tank and care about aesthetics, you may want to forego the Eshopps Eclipse as the weir teeth are cut very deep, making it very difficult to hide the waterline beneath the trim of the tank. I’m partial to Modular Marine as they have a notched exterior box to accommodate the tank trim so you can hide the waterline.

8E4EC34B-A4E3-4FA2-A3D3-0943B8C35E94.jpeg


Here is my center positioned Modular Marine ghost style overflow with dual 1/2” returns...

09A22215-955E-47CD-BEE2-BBFC6CA1B347.jpeg
 

Borg

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If you’re gonna drill your tank and care about aesthetics, you may want to forego the Eshopps Eclipse as the weir teeth are cut very deep, making it very difficult to hide the waterline beneath the trim of the tank. I’m partial to Modular Marine as they have a notched exterior box to accommodate the tank trim so you can hide the waterline.

8E4EC34B-A4E3-4FA2-A3D3-0943B8C35E94.jpeg


Here is my center positioned Modular Marine ghost style overflow with dual 1/2” returns...

09A22215-955E-47CD-BEE2-BBFC6CA1B347.jpeg
Thank you. I’ll check that out. My tank has a black trim on it. I’ll think about it
 
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I used a CPR overflow on my first tank and had several pretty bad spill over incidents due to issues with the water lifter pump setup. Glad I don't have to deal with that anymore.
 

2Sunny

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Bad news. The siphon stopped twice now since removing the sponge. I had a shutoff connected so no flooding, but not understanding why this thing can't hold siphon seems like a really simple setup. Any more guesses from the experts?


 

Water Dog

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I’m on an iPad so your video won’t play for me... a few questions, based on your earlier pictures, there are no restrictions, valves or anything from the external drain box down to your sump, right? With the sponge removed, it’s just and open pipe down to the sump, right? When you say it breaks siphon, what is happening? Is there air trapped in the U-tube, thus no more water pushing through it causing your refugium tank to flood or is it the external overflow box that’s flooding?
 

2Sunny

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I’m on an iPad so your video won’t play for me... a few questions, based on your earlier pictures, there are no restrictions, valves or anything from the external drain box down to your sump, right? With the sponge removed, it’s just and open pipe down to the sump, right? When you say it breaks siphon, what is happening? Is there air trapped in the U-tube, thus no more water pushing through it causing your refugium tank to flood or is it the external overflow box that’s flooding?

Hey Leon,

No restrictions. It has an internal box with teeth, and the two section external box and the siphon tube, and pretty much that's it. The external tube is a straight shot to the sump. When I find the siphon stopped the tube has air in it and the refugium flooded and no flow to the external box. The pump in is very very low flow. Probably on the order of 50 gallons per hour.
IMG_0592.JPG
IMG_2699.JPG
IMG_3696.JPG
IMG_9584.JPG
 

Water Dog

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The slow flow 50 gph pump is the most likely culprit. With such low flow pushing through the U-tube, air gets built up over time, accumulating in the U-tube and eventually breaking the siphon. I would suggest at least 200 gph in order to maintain the siphon through the U-tube. You need strong flow through the U-tube to prevent air from collecting in it. If you want to maintain that slow 50 gph flow through your refugium tank, perhaps it would be safer to replace that setup with the Glass Cages drilled tank.
 

fishybizzness

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I have a lifereef hob and have never had it fail. I do however clean the u tube every few weeks because I notice that when build-up starts to accumulate in the tube an air bubble starts forming. I don’t want to take any chances so I try to keep it clean. Maybe u can try and see if having in clean helps with the problem.
 

Brooke24

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My marine depot OF-300 is dead silent. Here is how I did it.

  • Install a ball valve/gate valve on the return line and the overflow line.
  • Adjust them so that you have just under a cm of water above the drain pipe of the overflow box.

I do not use the sponge silencer it comes with, I just use the white pipe that is supposed to be inside the sponge silencer.

Edit: Added a picture for reference. I am doing a tank reset and hence do not have a picture of it working.

IMG_0704_1.jpg
I bought the recommended size for my tank... I’m still not sure it’s big enough, and I’m very worried. I bought an of-800 for a 90 gallon tank, although it’s recommended for up to a 120. Will this be good enough?
 

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