View Full Version : Help with DIY C2C Internal Overflow

08/03/2017, 06:05 PM
I am ready to install a glass C2C overflow in my 100 gallon rimless tank. I already have the 2 pieces of glass cut and will be using Momentive 103 silicone for the assembly.
What is the best way to put it together, assemble the L first then install in the tank using blocks of wood for positioning? My concern is that I have read that all the silicone should be applied at one time.
Are there special clamps that I can use to hold the glass in position while the silicone cures?
I have searched the forum before posting.

08/03/2017, 07:14 PM
I usually assemble the overflow & let it cure then silicone it to the tank in one piece. The silicone will stick just fine because it is new, fresh clean silicone. It adheres to silicone as good as it does anything else. It doesn't adhere to old dirty silicone.

If u only have two pieces of glass then I take it as u have a true c2c box. Being that is the case u will probably have to build it in place. Being your tank is rimless I assume it is eurobraced so u probably won't be able to get the box in the tank if it's already assembled. If it's not eurobraced & u can get it in the tank I would assemble it first, then silicone it to the tank.

If u use clamps u may think about using a block of wood between the clamp & the glass. Depending on the type of clap u use it may pressure point the glass when u tighten it, so the block of wood keeps it from doing that.

If u can assemble it first U may find it to be easier to lay the tank on its back to silicone it to the tank. Something else that may help if u decide to make a brace to hold it. Instead of trying to brace it from the bottom of the tank u can make something to actually hang on the top of the tank that hangs down for the overflow to sit on.

It will be easier to assemble it first then silicone it to the tank after it dries. So if u can't get it into the tank with it assembled u can go ahead & put the glass in the tank & assemble it in the tank. Once it dries then u can silicone it to the tank. If that how u do it u can do like I mentioned & make something to hang on the tank that the overflow sits on, then use a couple clamps to just hold it in place to keep it from moving. Or lay the tank on its back & silicone it to the tank like that.

Btw, if u have never used the rtv before u may want to play with it a little bit on some scrap glass before u go messing with the tank. It is a very good silicone but it's not like using other silicones. It is harder to use then normal siliconed & u can make a mess or end up having to redo it if u don't know what to expect

08/03/2017, 07:28 PM
Lsufan, thanks. The tank is not eurobraced so there is no problem in getting the L piece into the tank. I am also making a sump from a 40B so I can practice using the silicone on installing the baffles in that.
BTW I am doing a Bean Animal overflow as the tank is already drilled for that.