Silicone and glass baffles


New member
I measured the tank I'm going to use for a sump and had some 1/4" glass baffles cut at a glass shop. I measured to leave about 1/16" gap.

When I put the baffles in, I see now that my tank is not square. There is still the 1/16 gap at the bottom, but the gap gets bigger higher up.

How much of a gap is too big to fill with silicone?

I'm guessing this will be too much, anybody have a trick to jimmy rig something to make it work? Glass isn't cheap around here, these cost me about $120 and I really don't want to toss them lol.

Vinny Kreyling

Premium Member
You should be fine with a heavy bead where needed, just takes longer to dry.
Just remember to get it done all @ once. New silicone will NOT stick over old silicone.


New member
Fill in the gap and seal on both sides of the inner baffles. On the tall outer ones fill in the gap and seal on the outside entirely and seal as much as you can on the inside. The inner ones are more important to keep critters from leaking out.

I have used a foam paint brush inserted into the finger of a surgical glove to spread the silicone on the inside of the outer baffles so I can get all the way down before.

Next time buy plexiglass and cut it yourself using a fine tooth circular saw blade with the blade running backwards. Then sand with a palm sander to get it perfect. I do that then I use a heat gun to carefully melt the edge to a glass finish. Save $. Absolutely not necessary but I had nothing better to do.