To overflow or not to overflow...

[RLG2182]

So I decided to make my own sump for my 60 gal. Was going to either go with a 15 or 20L. I know it's common practice to use an overflow box, but is it really needed?

I have a battery backup to guard against power outages. I can put a sponge over the syphon tube to guard against small fish getting sucked up. And I can make sure not to put the syphon tube too far down the aquarium to make sure excess water isn't syphoned out in case of an accident.

Has anyone bypassed the overflow box, or can advise against it? Could really put the extra $60 into a better pump, and could certainly make my tank look nicer w/o a large box taking up room.

 

[electrikat]

As long as your sump can handle the additional gallons of backflow when the power goes off, and as long as your return line has a hole in it above the water line( to prevent backsyphoning) you probably don't even need the battery backup. When the power goes off the hole in the return line breaks the syphon so the return line cannot drain back then the extra space in the sump is so that the water below the drain line will have somewhere to go. Most people only keep about 1/2 of the sump filled at a time to allow for the drain back in a power outage. We have a 10 gallon trash can for a sump and keep it about 1/3 full. When the power goes off we get about 3 or 4 gallons of drain back which leaves plenty of room for error. We have lost power several times and have never had a problem with flooding.

 

[RLG2182]

Thanks for the advice!! One thing: not sure if I read correctly, but you're saying to have a hole in the return line to prevent backsyphoning? Which return line? I've only heard of having the hole just below the water line in the hose that feeds the sump, not a hole above the water line in the hose that returns water back into the aquarium. Clarification?

 

[RLG2182]

Just to make things easier... where you thinking of putting holes? Position 1,2,3, or 4? (forgive the cheap/fast drawing)





(same image, pasted twice on accident)

 

[bound_for_obx]

Check out this link. It may answer some of your questions. You may also want to search around in the rest of the melevsreef's site there is a good deal of useful info in it.
http://www.melevsreef.com/what_sump.html

 

[bound_for_obx]

You will need an overflow box. It will be impossible to match the flow of the return pump to a simple siphon (the kind that you would use if you were "borrowing" some gas)

 

[RLG2182]

What if a flow-control valve was used on the intake syphon tube? Most people here use 1" tubing, but 1 1/4" could easily increase flow if needed, regulated by a simple valve to match syphon speed and pump return speed. Thoughts?

 

[Brad]

Take it from us...this is not a good idea.

If you can't drill the bottom of your tank, the overflow siphon box is a time proven solution for lots of reasons.

 

[RLG2182]

Thanks for the advice, not trying to be stubborn, just trying to learn. Checked the link (good one for explanation! Nice pictures/directions too ). Just think I can handle more than a "take it from us" answer for lots of reasons.

From what I got out of the link, the main advantage of the box was to be able to start the system back up when power turns back on, correct?

So if the overflow box remains primed, when water pumps back into aquarium and levels rise back to normal, water will drain back down into sump completing the cycle again... correct?

Otherwise, w/o the overflow box, the pump would return water back into the tank, but with an unprimed intake hose, water will gush over the edges of the tank... right?

I can easily afford an overflow box, so it's not so much a cost/diy issue, just wanted to know what actual concerns would be raised if an overflow was skipped. Thanks again!

 

[bound_for_obx]

Yes, with the overflow box, the system will start up again after power has returned. The problem of trying to skip the overflow box and just using a siphon is that you will never be able to match the the water flow between the siphon and the pump. You will eventually either: overflow the sump, overflow the main, or the return pump will cycle between pumping water and running dry. As you can imagine, none of these are good things. A couple of thinks to keep in mind, with a "U-Tube" overflow, you want the water flowing thru the "U-Tube" at as high a velocity as possible. This will "pull" any stray air bubbles thru the U-tube and prevent air from collecting inside the U-Tube. With the "C-Channel" (Weir) overflows it is recommended that you use a powerhead to prevent air from collecting inside the weir. I believe that the melevsreef's site covers the use of a powerhead with the weir systems. It's a lot of information to grasp, and I hope this helps.

 

[electrikat]

www.nano-reef.com/forums/showthread.php?s=&threadid=35200&highlight=cheap+overflow
Here is a thread to the diy overflow we decided to "borrow".
We have been using it for several months and have never had a problem with it. The only thing we did differently was to use two u-tubes in case one lost syphon(and it has). Also to add the hole in he line from the return pump to the tank(just above the water line).

 

[the21kid]

I added a check valve between the return pump and the return outlet. Works everytime and ran about $35 but I think it's well worth it should the power go out. I have a 180 so changes can be tough. To alleviate some of the difficulties I used 12 feet of 1" ID tubing so that all I have to do is unplug the pump....remove from the sump of the Wet/Dry...place in new water (usually in a aquarium only trashcan) and plug pump back in. It returns all of the new water as if it were in the sump. Also it's a wise idea should you have many things plugged in to seperate them depending on usage need; i.e. the pumps for the overflows should be on the same power stip as the protein skimmer pump and wet/dry pump (or the like). That way you can turn off the overflows and the water pumps with one switch. You don't want them running if the water pumps are not. My .02