OK, I'll preface this thread with, yes, Im an idiot. For some reason I cant quite grasp the sump idea. Ive read a 100 threads and watched just as many videos on DIY sumps. Pretty **** simple and straight forward. Here's my delimma. Why do you need an overflow box?? Cant you just run one hose that is a straight syphon to the sump, then one hose with a powerhead/pump pumping the clean water back to the tank?? Of course, drill a small hole just below the water line on both lines in case of power outtages. Other than skimming the water, what purpose is the overflow box??
I need some sump advoce & help!
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mfdrookie516
Aquarium Free - 2+ Years
Welcome to AA 
The reasoning behind the overflow box is 1- in case of power outages and tank maintenance. If the power goes out, you lose siphon when the water gets to the hole you drill... when the pump comes back on, the water doesnt siphon again until you physically start it. 2- the overflow only allows what water is pumped back in to the tank to overflow... you cant control how much water is siphoned as easily as you can with an overflow. Im sure there are more reasons than that, but those are the only two i've thought about in planning mine.
The reasoning behind the overflow box is 1- in case of power outages and tank maintenance. If the power goes out, you lose siphon when the water gets to the hole you drill... when the pump comes back on, the water doesnt siphon again until you physically start it. 2- the overflow only allows what water is pumped back in to the tank to overflow... you cant control how much water is siphoned as easily as you can with an overflow. Im sure there are more reasons than that, but those are the only two i've thought about in planning mine.
wherearepeople
Aquarium Advice Apprentice
It would be nearly impossible to match the pumps water flow from the sump into the tank and the siphons water flow back down into the sump.
If the siphon moves more water than the pump does, the siphon will lower the level of the tank until it loses siphon and then your tank will overflow.
If the pump moves more water than the siphon, the sump will empty out int your tank and cause it to over flow and potentially burn out your pump.
An overflow box also keeps your tanks water level constant and all water fluctuations are reflected in the sumps water level.
If the siphon moves more water than the pump does, the siphon will lower the level of the tank until it loses siphon and then your tank will overflow.
If the pump moves more water than the siphon, the sump will empty out int your tank and cause it to over flow and potentially burn out your pump.
An overflow box also keeps your tanks water level constant and all water fluctuations are reflected in the sumps water level.
I do get it now, but you mentioned burning up the pump. Say youre using a powerhead that moves 100gph. I would think that an overflow box trickling would only dump 20-30gph into the sump. So wouldnt the powerhead eventually suck all of the water in the sump out? Granted, the overflow box would fill quickly, but It wouldnt keep up with the powerhead. Does the overflow need to have larger piping or can I use 1/4in pvc for both sides? Im really wanting to use the minimum amount of harware that hangs on the tank. I thought I would try the PVC overflow that Ive run across. Oh, what should I use for a check valve?I guess the real way to get the idea is just experiemnt and hands on.
wherearepeople
Aquarium Advice Apprentice
I'm using inch and a quarter pvc and am currently pumping roughly 1000gph through my overflow
ccCapt
SW 20 & Over Club
1st off, you may be confused. A powerhead is used inside the tank for water circulation. You need to use a pump in the sump. But if the pump pushes 100 gph, that's what the overflow will drain back into the sump....no more, no less.
Your pretty brave...or not worried about it failing and causing a flood. I wouldn't use something like that...EVER. Reefkeeping is not cheap. Spring for the $60 or so and buy a HOB overflow.
Reef Aquarium Filtration: Eshopps Overflow Boxes
Why do you think it might fail? Its essentially the same thing as a HOB box. The hab box with the overflow in the tank have a syphon, as does the one I linked. Im not questioning ya, just trying to learn all I can before I build one. I was under the impression that the whole point of a sump is to minimize tank clutter, including stuff hang off the back ( more than 1"-2" that is).
A pump/powerhead are one in the same. They pull water from one place and force it to another.
Maybe Im missing something, but if your sump holds, say 5 gal of water & your pump is pumping 100gph while your overflow is dropping 50 gph in your sump. Well isnt your pump eventually gonna overpower the overflow and pump all 5 extra gallons out and cause the pump to pump dry which can burn up the pump??
A pump/powerhead are one in the same. They pull water from one place and force it to another.
Maybe Im missing something, but if your sump holds, say 5 gal of water & your pump is pumping 100gph while your overflow is dropping 50 gph in your sump. Well isnt your pump eventually gonna overpower the overflow and pump all 5 extra gallons out and cause the pump to pump dry which can burn up the pump??
wherearepeople
Aquarium Advice Apprentice
The overflow box will only drain water to the sump if the pump pumps the water to the tank causing the water to flowbover the edge of the box
I understand that, but what happens if the overflow gets clogged or loses its syphon? Wont that burn up the pump once its pumped everthing back to the tank and the overflow isnt returning any to the sump? Also, wont that cause a little bit to flood over the tank??
jsoong
Aquarium Advice Addict
Try reading this (plus the link to the 3 part article at the bottom):
Melevsreef.com - What is a Sump?
This may clear up some of your confusion.
Essential, what you want to set up is an active return of water (pump) from the sump to the tank. However, the water return from the tank to the sump is passive. The overflow will only drain the water at the rate the pump is pumping, no more & no less. <This takes care of variation of pump output ..... no pump pumps at exactly the same rate all the time ... the flow rate goes up & down depending many things. That is why you must have a system that can handle the variation ... a simple siphon (or an active pump) won't do.>
The overflow should have a much higher flow capacity than the pump. That way, it can handle the pump flow even when there is some clogging or other problems. In addition, you should have room in the tank to handle all the water the pump can pump up should the overflow fails completely. <Say siphon failure ... although that should be near impossible if your overflow is set correctly.>
In a properly set up fail-safe system (see the articles), you have enough headroom in the tank should the overflow fails. <You also should have enough room in the sump in case your pump or power fails.> Proper setting of the water levels will prevent floods under all circumstances. It is true that the pump will go dry in an over-flow failure. Some people have a water level sensing cut-off switch to protect the pump. There are also thermally switched pumps that will cut off automatically when the water runs dry, preventing damage.
BTW - once you have your overflow/sump set up. You should test your fail-safe settings by:
1. cutting power to the pump with overflow functioning, &
2. deliberately break the siphons in the overflow with the pump on full.
Melevsreef.com - What is a Sump?
This may clear up some of your confusion.
Essential, what you want to set up is an active return of water (pump) from the sump to the tank. However, the water return from the tank to the sump is passive. The overflow will only drain the water at the rate the pump is pumping, no more & no less. <This takes care of variation of pump output ..... no pump pumps at exactly the same rate all the time ... the flow rate goes up & down depending many things. That is why you must have a system that can handle the variation ... a simple siphon (or an active pump) won't do.>
The overflow should have a much higher flow capacity than the pump. That way, it can handle the pump flow even when there is some clogging or other problems. In addition, you should have room in the tank to handle all the water the pump can pump up should the overflow fails completely. <Say siphon failure ... although that should be near impossible if your overflow is set correctly.>
In a properly set up fail-safe system (see the articles), you have enough headroom in the tank should the overflow fails. <You also should have enough room in the sump in case your pump or power fails.> Proper setting of the water levels will prevent floods under all circumstances. It is true that the pump will go dry in an over-flow failure. Some people have a water level sensing cut-off switch to protect the pump. There are also thermally switched pumps that will cut off automatically when the water runs dry, preventing damage.
BTW - once you have your overflow/sump set up. You should test your fail-safe settings by:
1. cutting power to the pump with overflow functioning, &
2. deliberately break the siphons in the overflow with the pump on full.
