overflow, so many decisions....

[nanopodreefer]

Hi, brand new to the hobby, well saltwater that is. Anyways, I have been trying to research all different types of overflow systems before ordering my new tank. Just wanted to hear some thoughts on which is the best type of overflow system to use. I plan on having a 100-150 gal built in wall mixed reef tank.

Basically, what are the pro/cons to each?
1. full tank height center/corner overflow, 1 or 2 ?
2. small box in corner overflow
3. hang-in-the-back overflow, notched out
4. full back tank overflow
5. typical over the top CPR type overflow

With reagrds to the corner overflows, similar to that of the AGA megaflow overflow, how does a person calculate the width for overflow glass pieces. Also would it be better to have two or more overflow lines drilled rather than just one big one?

Is there any advantage to the AGA megaflow overflow sucking water from different depths in the tank rather than the top, do you think this feature actually works and is it as effective as AGA says it is.

When I get my tank drilled I want to do it right. Any thoughts or other overflow setup ideas would be appreciated. thanks.

If there is a thread I missed that you know of please direct me there.

[bigger stretch]

opinions are like you know what's , everyone has one. That being said here is my opinion. I have had dual corner overflows with durso's , I have had the HOB box type , and I have had the drilled top back with a box , one variant uses two 90 degree pipe fittings instead of a box. My favorite is the drilled back and for these reasons. The drilled area , the holes , are in a low stress area and not under allot of water preasure , takes up far less room in the tank than the usual corner overflow with a hole drilled in the bottom of a tank. The tank can be bought as a regular tank and then taken to one of many aquarium stores to be drilled as the back is rarely tempered , thus allowing you to drain out of the center or the back or drill both sides or both and use one side for a recirculating feed or a feed from your sump. I am sure there are a few other pro's and cons however after having dual corner overflows with durso's in my last 120 I realized that allot of space was wasted , it was hard to aquascape around the over flows , and no matter how much I fiddled with the durso's I could never get them just right , one was , the other never was. ... well there you have it , one mans opinion.

[Delphinus]

I think some of the considerations will depend on what you want.

In some situations, you have a tank and stand, in a standalone situation. In this scenario you may prefer to have the bottom drilled so to minimize the plumbing outside of the stand.

However this at the cost of real estate in the tank.

A hang on the back overflow eliminates any space being used up in the tank, however with only one edge for the waterflow, can perhaps be prone to clogging more easily than say an internal overflow with three edges. However I don't think that's the hugest of concerns.

If you want to be really technical, then you should consider something along the lines of a "coast to coast" overflow. Feed your skimmer with raw overflowed water, the maximized overflow edge means maximized protein extraction (since proteins will float as a "surface skum").

To be honest though I wouldn't really sweat it too much. Make sure your overflow is sized for the flow you want it to handle, and have some fun. I've tried many different overflow styles and to be honest they're all the same in the end.. if they get the job done that's the most important.

However if I was to build a new tank from scratch at this point, I would be going coast-to-coast on the overflow. I let myself get talked into an "old school" corner overflow for my 280g by the builder... I do regret this a little bit, but I'm not changing it now, I'm not hauling that tank out my basement for that!! In the end it was little cheaper so I guess it wasn't a huge loss.

[mark]

Though unable because the way I display my tank, seems the coast to coast the best or even partial such as untamed http://216.187.96.54/vbulletin/showt...&highlight=400

Another interesting concept was what Dale has in this thread: http://216.187.96.54/vbulletin/showt...light=overflow

RC has a calculator for a smooth weir, and if you're interested send me a PM as I've got similiar for a slotted weir (I got fr RDO)

[Dave C]

One thing to consider with an external overflow is the space available behind the tank. My tank is about 2" from the wall, and that was where I wanted it. That ruled out an external overflow. A corner overflow is easier to hide IMO because it's typical to have a tall rock structure on one side whereas a tall structure in the middle isn't as attractive. I consider a coast to coast overflow but then I've got the entire back side of the tank using up the available width. I'm sure it skims better but I wouldn't want a shelf running the length of my tank. If I could go external that would be a good thing, but not internal. Again, these are all just opinions.