weight of external overflow box

[treesprite]

My glass external overflow weighs about 4 lbs, and I am wondering if this is too heavy to expect silicone to keep it in place (I have no idea how much these things usually weigh). It is made of 1/4" glass, dimensions are 18x6x6, no front wall or top, 3x 1.5" holes. It is for a 75g tank. The silicone I'm using is from ASI and is specifically labeled "Aquarium Sealant". I won't actually be attaching it to the tank until after I get and install my internal overflow.

 

[mcgyvr]

Gussets under or even just a piece of glass added under the overflow box pressed up against the back of the tank to give the box an edge to sit on is always a good idea with external boxes..

 

[treesprite]

Gussets under or even just a piece of glass added under the overflow box pressed up against the back of the tank to give the box an edge to sit on is always a good idea with external boxes..

Thanks for the advice. That is what I'll do.

 

[mfinn]

When my tank builder made my external overflow box, he asked me to make sure I supported the 3 drain pipes coming out of the bottom.

He said he used Momentive RTV on it.

 

[treesprite]

When my tank builder made my external overflow box, he asked me to make sure I supported the 3 drain pipes coming out of the bottom.

He said he used Momentive RTV on it.

Another good idea. Thanks. I guess that is to keep the weight and vi rations or movement of pipes from pulling on the box.