External overflow?

[rustyjames]

Just got a 40b and would like to go with an external overflow (nothing in the tank). What would be the best way to go about drilling teeth in the back of the tank? I've done lots of tile but never worked with glass. Any advice would be great.

[das75]

Just got a 40b and would like to go with an external overflow (nothing in the tank). What would be the best way to go about drilling teeth in the back of the tank? I've done lots of tile but never worked with glass. Any advice would be great.

I'd just skip the teeth and do a notch. If worried about jumpers can added eggcrating.

for cutting seen started with a hole saw for rounding the corners then a dremel, or skill saw with a diamond tile blade to connect.

[coralnut99]

I'd just skip the teeth and do a notch. If worried about jumpers can added eggcrating.

for cutting seen started with a hole saw for rounding the corners then a dremel, or skill saw with a diamond tile blade to connect.

+1

From experience, I'd advise to leave the "corners" of the opening rounded. In other words drill two small diameter holes in the lower corners and connect them at the bottom of the radius. You run the risk of chipping a squared off corner. The nature of glass is such that under pressure that chip becomes a weak point that can run straight to the opposite side. I've made several, and I stoopidly saw the chip in that corner and thought nothing of it. Thank God I was in the room when it blew out.

[rustyjames]

Searching for info I saw people just doing a notch and siliconing a piece of acrylic with teeth cut in over the notch. Just thought cutting teeth into the tank itself would result in a cleaner look. I have a Dremel, circular saw and angle grinder but don't you have to use water to cool the blade and glass?

[rustyjames]

Das and Coral thanks, my original thought was to use a diamond drill bit to make a series of pill shaped teeth 1" x 1/4" if that makes sense. I guess a notch is the better way to go?

[boatbuilder]

been there done that on my 240gal...1/2" glass
pm me for my phone# and I will tell you how to do it......I hate typing!
will send pix to anyone who asks
Darrin

[windupdevl]

I assume you plan on not leaving the back of the tank clear....so why not just cut a notch out of the top of the back glass panel as mentioned above. Then cut weirs in the appropriate place on a piece of 1/4" black acrylic (or blue or whatever color you prefer)that is cut to fit perfectly inside the tank. I'd run a bead of silicone along the bottom and sides of the acrylic panel just to hold it in place against the back glass....I hope that makes sense...lol

[rustyjames]

windup, I really don't want to cut the trim and the whole top of the tank, which I think that's what you're saying. It's going to be open top (no canopy) that's why I wanted to notch the trim in the back a little and drill teeth, keep it very clean. Thanks.

[coralnut99]

Honestly, I thought about the whole notches in acrylic thing. After years of watching how the teeth in the HOB overflows worked in my other systems, I decided to leave the weirs in the externals on my 3 frag tanks flat. I think you'll find lots of agreement that theeth in overflows actually impede surface skimming. I just squeeze-fit a small piece of eggcrate over the weir on the outside to keep snails out, and I couldn't be happier with it.

[craighenry]

i was able to cut out 20 x 1.5 in my 20l, without cutting/removing trim. i used a dremel for the whole thing. you just have to slowly cut up in between the trim with the end of the bit. it takes a while but it can be done

[rustyjames]

What bit did you use? And did you use it dry?

[Lyfey]

My next system Im not having "teeth" so much algae grows in my teeth of my RR 75. It took me a while to get all of it out and after that have noticed a huge change in the quality of water.

[craighenry]

the bit i used is labeled for wall tiles..i think and yes i used water