"U" vs "C" overflows

[JeffProe]

I'm working on getting a 55g FOWLR going and I'm in the market for an overflow. I've been looking at the C type overflows because they seem to have a higher capacity in a smaller package. But, I just read somewhere that they don't maintain their siphon well. Is this true? Can you guys share your experiences with either type?

Thanks in advance!

 

[fishfreek]

What kind of flow rate do you need? I have a U tube overflow thats rated upward to 1400GPH. So dont get tricked into thinking U tube overflows will only do 600-700GPH.

Yes the c shell overflows suggest you have a powerhead attached to the overflow to maintain the syphon and to help with the startup of the syphon when a power outage occurs. U tube overflows dont have such issues if they are sized properly and are maintained properly.

 

[JeffProe]

I don't think I need a tremendous flow rate with only a 55g, but I was under the impression that with comparable flow rates, the C type would be smaller. True or not true?

 

[fishfreek]

Yes the C style overflows take less space in the tank.

 

[JeffProe]

Ok, so is the possibility of it loosing it's siphon a huge deal, or if I have a power head that will accept the air line tubing and will suck the air out of the C am I ok, or are they pretty much equal and I should just get the proper flow rate, and not worry about what type I get?

 

[fishfreek]

In my house losing syphon is a big deal. That means upward to 25 gal on the floor should the tank lose syphon the pump in the sump will not stop. So it will overfill the tank and the water winds up on teh floor.

The c shell style do often suggest a powerhead to help keep air out of the C area. Its important to pick a relyable powerhead. In my book stay away from RIOs for this function as they are not overly relyable to start up when you neeed them to be.

U tube overflows dont need the powerhead to keep the syphon but the down side is they are a bit more bulkyi nthe tank as they have a 3/4" - 1" hose going up and over the side of the tank vs a low profile but long C shell type syphon.

 

[fishfreek]

I would like to add that these are my views on the different types of overflows and there are many folks who have used the c shell overflows and have no issues with them.

 

[JeffProe]

Hey, thanks for the input! I didn't mean to sound like lost siphon isn't a big deal 8O . What I meant was, is there conciderably more risk of it happening witht he C type vs. the U.

Again thanks for your input!

 

[loganj]

The only C type overflow I have ever used was the Marineland model. I can say that losing the siphon would have been a problem without the MJ1200 powerhead that I had attached to it. The C tube collected a lot of air. I have never had this problem with a U tube overflow. If you do decide to go with the C type, I would use either an MJ900 or 1200 powerhead on it and I wouldn't even consider any other type. JMHO.

 

[Brad]

Why not put a powerhead on a "U" type? If "U"s are that reliable, they should be super reliably with a power head to ensure they restart.

Bear in mind that the siphon can stop for other reasons besides air. The most common would be some sort of object (ie. snail) blocking the tube. Do what you can to guard the entrance to the siphon.

 

[loganj]

Why not put a powerhead on a "U" type? If "U"s are that reliable, they should be super reliably with a power head to ensure they restart.

If it's set up properly, the powerhead isn't really necessary. The problem that folks have run into in the past is that when the power comes back on, the powerhead doesn't restart. That's why I wouldn't use anything other than a maxi jet on them.

 

[Hara]

I have also found that the size of the overflow box would not allow for the powerhead, nor lines from the powerhead to the tube to fit. It is a pretty tight
squeeze in there.

 

[fishfreek]

Unless you run the U tube at a rate much slower than its rated for, 200gph on a 600gph overflow, for example there wont be air collecting at the top of the U tube. The flow rate is so fast thru the tube that air gets pushed along by the water. The overall flow rate might be the same on the C shell style but the speed that the water flows is slower because there is greater surface area for that water to move thru thus air has time to collect at the top.

For a snail to get into the U tube, and Im not saying it hasnt happend before, its quite an adventure. First the snail has to get over the oveflow fingers. This usually means venteruing out of the water for a period. Then the snail would have to make its way down the inside of the overflow box. And then find a spot on the back of the overflow box to hitch a ride on the U tube thats sitting inside the overflow box. They would then have to travel down the U tube and turn up inside the tube itself. Depending on how close the bottom of the tube is to the bottom of the overflow box the snails shell may physically not even fit between that space.

In the c shell style the back of the overflow box is part of the water channel that routes water up and over the back of the tank.

 

[cj10488]

I have a CPR CS90 on mmy 55g tank.. It works great.... It was a pain and constantly wanted to overflow without using some sort of pump.. I ended up going wiht an Aqualifter pump and have never had an issue since... I am having a custom u-tube overflow that will handle atleast 1600gph made for me by a friend so hopefully i will have the same luck..

I really like the CPR style overflows though.. And thats a personal experience.. Just get the 12.00 aqualifterpump that goes with it.. check out www.amekaaquatics.com and you can get factory seconds on the stuff for pretty cheap as well..

HTH<
JAmes

 

[Brad]

I discovered a 6" brittle star living in my CPR overflow. I had been wondering why I hadn't seen him in some time. I estimate he had been in there for two weeks. The mesh caused him no trouble at all as they are masters of the tight squeeze.

It was quite difficult to get him out actually.