external overflows

[BCreefmaker]

i had a question about this type of external overflow. overflow . i was wondering if anyone has used one and had it fail or heard of them failing with the auto start? i was planning on hooking it up to a freshwater tank, but i would imagine people in the SW world might have more experience with this product.

[saltwatercityma]

An accident waiting to happen-Drill the tank you will fare much better

[der_wille_zur_macht]

CPRs and other "continuous siphon" models have a poor reputation, so make sure you keep an eye on the aqualifter pump. If it fails and your overflow breaks siphon, it's all over.

I will also echo what the other member said - if you can, drill your tank.

And, for reference, this style of overflow is generally called a "hang on" overflow. The phrase "external overflow" usually refers to a permenant fixture on the outside of a tank, with either a hole drilled or a weir cut in the lip of the tank for flow.

[THE ROOK]

LifeReef builds some of the most reliable hang-on overflows. They have a very good rep on here.

[Sugar Magnolia]

Originally posted by THE ROOK
LifeReef builds some of the most reliable hang-on overflows. They have a very good rep on here.

That's what I used. Excellent HOB overflow.

[der_wille_zur_macht]

Originally posted by Sugar Magnolia
That's what I used. Excellent HOB overflow.

I've had several of theirs as well, and liked them. Even ran a big tank (a 125) off their overflows. Still used an aqualifter to keep the siphon going, though - even though that (riskily) claim you don't need to.

Depending on the flow rate you put through one, you'll probably want to toss the standard sponge "silencer" that comes with many hang-on overflows and use a durso or stockman standpipe, instead. It's really hard to get the sponges quiet if you're putting a lot of water through them.

[shaginwagon13]

Originally posted by saltwatercityma
An accident waiting to happen-Drill the tank you will fare much better

+1!!!!!!!!!!!!!!!!!!

I made the mistake of getting external overflows and it was the worst thing ever! Sometimes they loose suction....they require a small pump to keep them going and after a water change sometimes its hard to get back going.

My next tank will DEFIANTLY have internal overflows!

[singold]

Mine works great, have never had and issue.

[seapug]

The simple U-tube style ones (like lifereef, Amiracle) are better than the CPR ones or any type that requires a pump to maintain suction through the siphon. The U-Tube ones are designed so that both ends of the tube are kept submerged in water when the pump is shut off. This keeps the siphon in a state of "suspended animation". As soon as the pump restarts the siphon will resume.

I've been using one on my 90 for almost 3 years now and have never lost siphon despite numerous power outages and weekly pump shutdown for maintenance.

Starting the siphon the first time is a little scary, but very simple once you get the hang of it.

[FirstContact]

+2 on DRILL the TANK

1) Ask the manufacturer which sides of the tank are tempered
2) Purchase some glass hole saws from Richon Tools (Google)
3) Take the tank and the hole saws to a glass shop they have a drill press

[FirstContact]

BTW, nice avatar singold...

[ryno726]

I have only had a problem one time with the U tube type overflow, somehow the tube got an air bubble in it and the sump pump was pumping my sump dry into the display, almost overflowed! If I had an empty tank, I would drill.

[der_wille_zur_macht]

Originally posted by seapug
The U-Tube ones are designed so that both ends of the tube are kept submerged in water when the pump is shut off. This keeps the siphon in a state of "suspended animation". As soon as the pump restarts the siphon will resume.

Just for clarification, it's possible to design either style of overflow (u-tube or continuous siphon) with this feature, though it is more commonly found on u-tube models. And, since a u-tube model will typically have a smaller cross-section for a given flow rating than a continuous siphon model, features like this are more likely to work on a u-tube model.

At any rate, if you use a hang-on, no matter *what* features it has or what brand it is, follow this rule: ALWAYS employ some method to "restart" or maintain the siphon, regardless of siphon preservation features. The easiest way to do this is to use airline run to the highest point in the siphon (continuous siphon models often have a nipple for this, for u-tube models just run the airline up inside the tube). Then, connect the other end of that tube to an aqualifter pump. The output of the aqualifter should be directed into the outside compartment on the overflow. If you don't want to use an aqualifter, you can attach it to the venturi intake on a powerhead in your display tank, if you have one.

Even if there is a built-in siphon preservation feature, such as keeping both ends submerged when the return pump goes off, it is still very easy for a few air bubbles to collect in the tube, which make such features useless. That's why it's important to have an aqualifter pump or powerhead venturi sucking away on that airline - it'll suck bubbles out of the siphon and keep it working correctly.

Also, contrary to what common sense might tell you, it is much safer to run a hang-on overflow as close to it's flow limit as you dare, than to run it slower. An overflow rated for 1200 gph but being run at 300 gph will very likely lose siphon and/or have all sorts of other siphon-related problems. However, run that same 1200 gph overflow at 1000 gph, and the problems will be far fewer.

[kilroy217]

I am using the exact overflow that the OP linked to. Tried running it without the aqualifter, and had many bubble constantly getting into the chamber. Bought an aqualifter, and leave it connected and running 24-7, and haven't had any problems since. Even with a power outage, once the power kicks back on, the aqualifter will get the siphon going right away. This is a great model if you have an existing tank that you want to add a sump to (which is what I was doing when I set it up).

One question, though - for Freshwater, I didn't think you needed a sump... why are you setting up any overflow?

[singold]

Thanks "FirstContact". I think drilling a hole is better obviously. But as another post stated, if your tank is already set-up, stocked, etc. then overflows are an alternative. In my case my tank was set up for almost a year, and wanted to add refugium to system, so used the overflow box option.

[Stevenx2]

I had 2 different externals, CPR (I am quite surprised that nobody has sued the cr*p out of them yet) and Lifereef (I think that was the company). Well Lifereef was the better one by far BUT, a HUGE B-U-T do yourself, your floor, your nerves, your wallet and your girlfriend a favor, drill your tank!

[FirstContact]

Adapt & Overcome! Oohrah overflow!