I would use 3/8" for a tank that size.
Not to hard to glue up space the BTM up about an 1/8" and don't squish out too much silicone you want to keep at least a 1/16" between your joints.
Mask off your joint ends and remove the tape before it dries for nice clean seals. Leave the tape to hold it together on for at least three days.
I had a link for some trim will post it if I can find it, but if you have clean glass cuts not all that necessary.
__________________
150 Gal system 3'x3' 400W M/H, Bekett skimmer, Dart return,1/4 HP Chiller
180 Gal Drop tank, LED lights, Bubble master 250 skimmer,Hammerhead on a closed loop, Speed wave return.
|