external overflow slot

[eameres]

Just wondering why most external overflow advocates are using the "teeth" approach rather than going with a horizontal slot.

I'm contemplating the purchase of a 120XH perfecto, and was considering cutting four 3" long x 1/4" high slots just under the top frame on oen of the short sides of the tank and then building an external overflow. I'd leave about 1/2" between each slot and it's neighboring slot.

picture this: | _____ ______ ______ ______ |

My rational is two fold: Anthony Calfo says it's better to skim from the very surface of the tank, and IF there were to be a failure, it would probably result in a horizontal crack along the top of the tank, rather than one running diagaonally, or top to bottom.

Any thoughts or advice for or against?

Oh, btw, I figured I'd use my dremel and a straight edge guide of some sort to grind out the slots.

[Osler@thesea]

Your planning on cutting these slots in the glass, correct? Based on Perfectos specs for that tank, it is made of tempered glass and is not drillable.

http://www.perfectomfg.com/tankspec.htm

If it was drillable, this is a viable option. However, the easiest thing to do is drill for a bulkhead and then install an opaque overflow within the tank, IMHO.

[eameres]

The bottom is definitely tempered, but I'm not certain about the sides. Perfecto will drill the side or bottom of the tank if I wanted to go with overflow box internal to the tank. They say on their site they will sell you one untempered if you order it special.

I'm just mulling over what the optimal approach would be if I wanted to get the best skimming, the least potential for cracking, and no box in the tank.