Drain questions

[trouble]

yeah sorry an overflow

[mike31154]

Many tank manufactures offer tanks with plastic/acrylic overflows siliconed to the glass walls of the tank itself. I reckon the reasoning is that typically your overflow is not subject to the same stress and pressure of containing, say, 90, 120 or more gallons of water. And as you suggested, if the seal is compromised, it's not necessarily a disaster in the making. If it's a good silicone job, there should be no problem.

The only other issue I'm aware of is the different expansion rates of acrylic vs glass. This can cause a seal to eventually fail when subjected to large temperature changes on a regular basis. When I build the sump for the 90 I plan to set up, I was thinking I may use acrylic for baffles (plan to use an old 65 gal glass tank). Instead of trying to silicone the acrylic in, I thought I might silicone two narrow pieces of glass on each side, thereby creating a sort of slot to slide the acrylic into. Of course a perfect seal is not really required here, whereas for your application, you'd likely want something with a little more integrity. Could still apply silicone to the acrylic before sliding it down the slots though.

[trouble]

yeah, i think im going to go with glass seems to me i skirt a lot of issues by going that route. really the only reason i was thinking about going with acrylic was because i figured it would be easier to cut the grate/teeth into it around the top. as far as seeing into though i am going to go with tinted or smoked glass i dnt want to see the plumbing behind it. so i will make the overflow out of glass and i've bee thinking of making a lid to fit to keep the light out of the overflow, so i think ill make that out of acrylic and put the teeth into a lip on the underside of the lid. the only thing i am undecided on is wether to have the overflow extend the full depth of the tank or just take up say 6" or so at the top.

[mark]

Couple of things
-your overflow doesn't need notches
-check Reefjunkies build for a Herbie using bulkheads on the side (and chamber doesn't need to go to bottom of display)

[KrazyKuch]

you can always go with a glass overflow and just stop the glass below were you want the notches, then you can silicone a piece of acrylic to the face with the notches in it!!!