First of all, there is no such thing as a dumb question. Your concern has been shared by many before you, and will continue to worry many hobbyists to come.

If your sump (and it's related plumbings) was designed properly, a power outage should not cause a flood. When you experience a power outage, the return pump will cease (obviously), as will your skimmer pump. The water in the tank will then drain to the level of the overflow. Usually, thats about 1/2 inch below the normal operating level. So long as you have a siphon break (a hole in the return line just below the water level of normal operation) the tank should not drain beyond this point. A properly designed sump will have accounted for this occasion and should be able to house any water that it may accumulate from the tank, the skimmer, and any plumbing.

Problems generally occur when people either fail to install a siphon break, or their syphon break hole becomes plugged over time. when this happens, the return line will act as a siphon and the tank will continue to drain until the waterline reaches the return outlet. Once the water reaches that point, air will enter the return line, thus breaking the siphon. Unfortunately, in most cases the return outlets are several inches below the minimum level of the overflow, and our sumps cannot handle that much excess water, so we end up with a flood.

So the key to remember here is, Make sure you have a siphon break hole drilled in your return line, and make sure you periodically check, and clean it out.

 

ThankYou for the great explanation.... Do you have pics of a sump with the siphon breaks visable???

 

I have a Diagram, hope it helps

 

I'm not sure I really understand the purpose of the siphon break, myself. I mean...I understand the purpose of it, but I don't understand why people set up their systems like that.

Typically, don't you have some sort of pump returning the water from the sump to the display? If so, why does the outlet for the return line even need to be that deep in the water? Couldn't the outlet be just below the surface, up near where the siphon break is shown in that picture? Or, couldn't you even have the return line come in above the water line?

I've never had an aquarium that used a sump before, so I'm just trying to figure out all of the ins and outs of them before I mess around with one myself.

 

The inlets serve the additional purpose of adding flow to different areas of the tank. Since corals need flow to aid in their capture of foods, and powerheads within the tank can be bulky and aesthetically displeasing, the inlets need to be directed appropriately to serve this purpose.

To have the oulet to high in the water will cause small whirlpools to form. These whirlpools create additional noise (a considerable amount of noise I might add) which is something of a concern for all reef/sump systems.

To have the outlets above water would cause two serious problems in the system.

A. Micro-bubbles which can lead to problems with corals, and makes your water appear cloudy.
B. excessive salt creep resulting from splashing water, and from the microbubbles.

 

Gotcha. That all makes sense.

 

re: sump question

LOL


You sound like me when before I hooked up my sump!!

The way it works is, an overflow box is installed (HOB) inside your tank. What is moved from the main tank into the overfill box travels down a tube and into the sump. A pump returns the water back into the main tank.

The overfill box will keep the water level at a certain height. As the pump returns water into the main tank, the over fill box is taking it out. If the power were to go out, the overfill box will continue to remove water up to a certain water level. The trick is to have enough room for the water to escape into the sump without overflowing the sump tank. This usually is a small amount of water, 5 gallons would be a lot.

There is a second part to this sump system. The output of the return hose has a little hole at the end of it. This hole will be kept in water to keep it air tight. The moment the water level falls (power failure) the hole will be filled with air. The air will break the suction of the return line which without this hole would become a syphon. If you keep a short return spout in the tank this would not a problem, but for fish keepers with a pipeline for the pump's output, deep into the tank, the tank could potentially be drained.