Overflow box necessary?

slider101

Member
When putting in a sump/fuge on a tank that is not drilled do you need an overflow box or can you use a syphon tube with a screen on it to keep critters from going up it? What does the overflow box do that a syphon tube would not?
 

slider101

Member
But is it necessary? If my syphon tubes are say an inch below where I want my water level and my return pump was keeping the water level full would that not do the same thing? If the syphon tubes were an inch under my water level that would stop it from syphoning out all my water in the event of a power failure once it reached below the tubes.
 

sk8shorty01

Active Member
slider, the biggest asset to the overflow box is the fact that it holds a syphon without drawing water because of its construction. What happens if your power trips for a couple minutes, the syphon tube draws that inch of water and breaks syphon, now the power starts up again and your pump starts returning water to the Display Tank, now you have no draw out of the tank and you are adding water. You will overflow your Display and also burn up the pump when the fuge/sump dries out. Its much more safe to go about it in the "best option available" rather than taking a short cut and getting burned in the long run.
 

slider101

Member
Originally Posted by sk8shorty01
http:///forum/post/3029115
slider, the biggest asset to the overflow box is the fact that it holds a syphon without drawing water because of its construction. What happens if your power trips for a couple minutes, the syphon tube draws that inch of water and breaks syphon, now the power starts up again and your pump starts returning water to the Display Tank, now you have no draw out of the tank and you are adding water. You will overflow your Display and also burn up the pump when the fuge/sump dries out. Its much more safe to go about it in the "best option available" rather than taking a short cut and getting burned in the long run.
I guess I dont get it. If the power goes out and the overflow box drains from the syphon then the power comes back on and the pump starts running how will the syphon start back up the tubes? Does the overflow box start its own syphon up or do you have to prime it?
 

pezenfuego

Active Member
Originally Posted by slider101
http:///forum/post/3029146
I guess I dont get it. If the power goes out and the overflow box drains from the syphon then the power comes back on and the pump starts running how will the syphon start back up the tubes? Does the overflow box start its own syphon up or do you have to prime it?
It's kinda hard to explain without a picture. The top of the tube that takes the water from the box (on the back of the tank) to the sump is higher than the bottom of the u-tube...so when water stops draining down tube to the sump, there is standing water that the u-tube is sitting in. Which prevents the water from draining down and allowing air into the u-tube. If you get air in the u-tube...you will have a flood when the power starts up.
Don't know if that helps, but overflow boxes (as ugly as they may be) are a lot safer to have. The last thing I want is a flood from my tank. My floors and tank will both suffer.
 

slider101

Member
Originally Posted by PEZenfuego
http:///forum/post/3029222
It's kinda hard to explain without a picture. The top of the tube that takes the water from the box (on the back of the tank) to the sump is higher than the bottom of the u-tube...so when water stops draining down tube to the sump, there is standing water that the u-tube is sitting in. Which prevents the water from draining down and allowing air into the u-tube. If you get air in the u-tube...you will have a flood when the power starts up.
Don't know if that helps, but overflow boxes (as ugly as they may be) are a lot safer to have. The last thing I want is a flood from my tank. My floors and tank will both suffer.
But when the box has pulled as much as it can in the tank until the lowest level that the box is set, the front of the tubes that are in the tank would pull in air right? Once it drains the box in the tank. When the pump came back on it seems to me that it would just start pumping back into the tank and the syphon would not start. I am sure they work or people wouldnt have them I guess I just dont understand what primes it back up after the front of the tube is exposed to air.
 
what primes it back again in water level. the box that is inside the aquarium is higher that the one outside the tank, just remember that in order to make a syphon you need to be lower that the water you want to syphon.now when power goes out both water levels from the two boxes become level and syphon stops and you will still have water in the u tubes.
 

pezenfuego

Active Member
Too bad I can't use models and hand gestures to help...
Some people even put in a small water pump to make sure that no air EVER makes it into that tube.
 

sk8shorty01

Active Member
The water level in the overflow box drops and levels out between the front and rear box, the tube that runs between the two boxes never brings in any air when the power goes out. Because the tube that connects the two never draws in any air the syphon is still active even when the power is out, there is just nothing to drive the water from the front to the back. When the water level in the front box starts to raise it resumes the syphon pull and draws water into the back box. Its a pretty nice set of engineering if you ask me.
 

slider101

Member
Originally Posted by sk8shorty01
http:///forum/post/3029686
The water level in the overflow box drops and levels out between the front and rear box, the tube that runs between the two boxes never brings in any air when the power goes out. Because the tube that connects the two never draws in any air the syphon is still active even when the power is out, there is just nothing to drive the water from the front to the back. When the water level in the front box starts to raise it resumes the syphon pull and draws water into the back box. Its a pretty nice set of engineering if you ask me.
GOt it! Now I understand how it works. Man, that made me feel dumb considering I am a technician! I didn't realize or think that when the level in the 2 boxes are level that it will stop flowing. Now does anyone have an old overflow box they dont need? THanks again!
 

slider101

Member
Another quick question. Does it matter where I mount the overflow box? Does it have to be in the middle back, side? I wanted to put it in the most inconspicuous place I can.
 

sk8shorty01

Active Member
You can put the box anywhere you want as long as it is hanging on the aquarium and its in the water. Most people put them where the rock work/viewing angle takes them out of sight.
 
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