Siphon VS. Pump

I'm purchasing either a 20 or 30 gallon aquarium today to build a sump/refugium. The biggest concern of mine is matching the flow of siphon coming into the aquarium versus what's being pumped out. How is this deciphered? By a shutoff valve on the siphon? I've read and viewed quite a few of the other threads and see no mention specifically how this is regulated. Thanks for the assistance.

 

the overflow should be rated for a certain gph. if the return pump is more than this u should put a ball valve on the return line to slow the flow down.

 

You'll want your return pump GPH to match the overflows GPH.

 

You should put a ball valve on the return line anyway. It makes it easier to cut off the flow for any kind of maintenance without flooding your room.

Not true. An overflow should be able to handle any number from 1 gph to its capacity just fine. You just don't want a pump that is greater; lower is ok, as long as the pump can handle the head loss.


To answer the original question: you use a siphon to get water from a chamber inside the tank to a chamber outside the tank. The chamber outside the tank drains into your refugium. A pump returns the water. The chamber inside the tank has an overflow. When the pump stops, the water above the overflow will stop flowing over the edge, and the siphon will stop binging water to the refugium.

Do you have a diagram of what, exactly, you were planning on doing for your fuge?

 

Very helpful. So I can get a pump that supports the overflows max and below. I.E. Overflow rated at 500gph, a 250gph pump is just fine? Now, that's assuming that the overflow pipe is directly into the water of the sump? Otherwise, if the overflow dumps directly into the water, it makes it easy to overflow and likely to exert water at it's max potential rating. Does that sound correct?

I'm currently at work, once off, I'll try to put a drawing or something together. I was actually considering what a few of these other guys with 20 longs are doing. The question is: return in the center or on the side? Appears mixed reviews.

 

What others have said. You can have an overflow rated for 500gph and a pump rated for 250gph. But not the other way around. Also, as a pump pumps water vertically, it loses gph the higher it goes. Some pumps or pump websites have a chart to help you match the distance from your return to your pump to what gph it is. For example, at 3 feet, our pump puts out about 600 gph. At 4 feet, around 500. Our distance is just shy of 4 feet (it's about 3.75 or so feet), so we got an overflow rated at 600. Works like a charm.

Also, you want to avoid using a ball valve or whatever to restrict your pumps flow rate. This causes the pump to work harder, and will burn it out much quicker. It's easier to just go up in an overflow size than to restrict the flow from the pump, and it's probably cheaper too in the long run.

 

I would do the return and overflow on opposite sides of the tank. It's really a personal preference thing, but this way allows for water that's coming back to circulate through the whole tank before it gets back to the sump.

 

Also, I forgot to mention that the diameter of your return also effects the gph it puts out. For my pump, only one diameter fits so I didn't have that problem of sorting that out.

 

Good info so far. From the overflow, you want pipe to bring the water into your sump, but as with the others, I'm not really sure what you mean by directly in the water? Also, some pumps are designed to handle back pressure or restricting the flow so the statement that a pump will burn out quicker from restricting its flow is not entirely correct. I restrict the flow on my return and have had no issues.

 

The motor in the pump will experience no wear; it will run at the same speed, always, regardless as to how much water it's actually pushing. The impeller may get beaten up a little bit more, but that's a very, very minor issue.