View Full Version : canister on an overflow? -> sump

12-26-2007, 01:47 PM
Can I hook up a canister to an overflow?
I am trying to learn about sumps and overflows
can i hook up a canister to the overflow until the sump details get figured out?


12-26-2007, 02:29 PM
I don't see why you couldn't as long as the siphon on the canister isn't broken. I would actually leave it just like that and forego teh sump.

12-29-2007, 01:22 PM
but there wouldnt be too much water overdoing the pump?

12-30-2007, 01:53 PM
I'm not following you on this one. A sump is an open system and a canister is a closed one. You use an overflow as a protection to prevent too much water entering the sump and spilling out as they are usually below the tank. The water you pump out of the sump goes back into the tank until there is enough in the tank to "overflow back to the sump. If the pump fails the water will drain back into the sump until the tank level is below the overflow openings preventing too much water returning to the sump. A canister filter draws water into itself directly reguardless of the level in the tank as long as no air enters the system. Most canisters draw water fairly deeply from the tank level to prevent air from entering. These filters are designed and operate completely differently from each other as far as getting the water in and out.

12-31-2007, 09:16 PM
I think metfan581 is asking whether it's OK to connect a cannister pump to an overflow, in other words; Have the input to the cannister filter via the drain from the overflow. If I understood his question correct, he is concerned that the water flow coming out that way is too much for the canister pump.

In theory, it should not be a problem as some sort of reducer would be needed to connect it to the cannister pump. The water going into the pump is still limited by how much water can be pumped out.

I see no benefit in doing this as oppose to using the regular intake. It may even get backed up as you may not be able to see the drain easily. I would not mess with this setup since you are using the cannister filter the way it's designed.

Just use the cannister filter for now and buy 1 rubbermaid tub to play/understand the sump system. You can even use an on 15 gallon tank if you have one laying around.

12-31-2007, 09:55 PM
Hey all,
I think my setup is kind of what you're asking about. here's a picture. It is 5 tanks connected together using 2 overflows, 2 pumps connected to each other and 2 pipes that are filled with water.

Take a look at the picture... The top 55g is overflowing on the left side into the bottom 55g, which is then overflowing down and across into the closest 10g, which then is connected via a water-filled pipe to another 10g, which is then connected to another 10g via a water-filled pipe. Then the last 10g has 2 pumps connected to each other in series... in order to overcome the water-head (about 3 feet that the water has to pumped vertically. The 2nd pump is an Eheim 2215 canister filter as well.

The overflows in each of the 55g's are designed to work even after the water has stopped flowing... so I can do water changes of more than 90% and fill the tank back up, and once the in-tank water level gets above the pvc pipe's lip, the water overflows into the pipe and into the next fish tank.




12-31-2007, 09:56 PM
oh yeah, the design has changed recently, this picture is from about 4 months ago, but i think it's still applicable

01-02-2008, 12:30 AM
Vlam, I understood what the question was, what I didn't understand was the point. The potential problem is that the canister pump can out draw the overflows ability to keep up if not sized properly which considering it is not necessary to work a canister filter makes no sense to use. In Reelay0's pictures his bottom tanks act as the sump so using a canister is just a means of filtering all the tanks on one canister system. The potential problem with this setup is if any siphons between the upper two and bottom tanks are broken it is possible the filter could send enough water to overflow the tank just before the broken siphon as you are dealing with more water than a normal sump where you assure that the sump volume will not overflow the tank it serves and the served tanks are not at the same level.

01-02-2008, 08:09 PM
I don't see where combining an overflow with a canister makes any sense either. Just use the canister as designed.

If your intention was to use the overflow as a surface skimmer, then just buy a skimmer accessory designed for canister filters.

01-04-2008, 09:53 PM
thanks guys for the help
the purpose was to have the canister as a temp until a sump would be decided on for the layout

this was just to see if it would work for a back up plann

02-12-2008, 02:08 AM
This is most likely a little late to add, but it could work. Since the overflow will only siphon the amount of gph that is being put into it. Where you would run into problems is if the overflow took a little to long to get going. I dont know if a canister would have enough water in it to push up into the tank to start the overflow before running dry. In a power shut off situation (as long as you have a good overflow) it would only suck enough water into the overflow box to level out the water in the skimmer box and the overflow. If you wanted to make sure it wouldnt run dry you would need to start the siphon on your canister and lower your skimmer box until the tubes and canister are full. Then raise the skimmer box to the level you want it to sit at, then fill the tank to the point were the overflow is almost full with out over flowing then turn on the system. You would just have to make sure your water level doesnt drop to much from that point. The main benifit would be the surface skimmer action. My experience in reefs states that this is a VERY important aspect. How important is it in fresh water? Not to important, since very few people have skimmers on freshwater tanks. Does it have potential benifits in freshwater applications...yes but in short it would be to much of a hassle and a very touchy system at best.

02-12-2008, 09:33 AM
thanks guys for the help
the purpose was to have the canister as a temp until a sump would be decided on for the layout

this was just to see if it would work for a back up plann

You don't need a sump filtration for discus. A canister or even a good HOB will be more than sufficient.