I've used this and don't like it. If you have any moisture behind the silicone it will grow mold. There's a good reason why they put mold inhibitors in it. I'd rather use an aquarium silicone. More expensive but that's what it was made for.
Silicone I will definitely work, but there are better products out there. I really like Momentive RTV 103. It is manufactured by GE and sold through industrial supply houses (I bought mine through Grainger). It cost a couple bucks more per tube, I believe it was around $8.00, but it is worth it.
well i finished resealing the 150. it held water to the half way point for 3-4 days felt confident to fill the rest of the way. Guess what soon as the tanked topped off it sprung a leak right in the middle at the bottom. glad i had 3 50 gal trash cans in my fish room. once tank dries start the process over.