I needed a sump that had the footprint of a 10 gallon but not as high and I wanted it to be cheap. So I got the idea to cut down a standard 10 gallon tank without taking it apart. This was surprisingly easy to do and only took about an hour. After it was all done I realized not only did this make a decent sump but would also make a great frag tank.

I started with a standard 10 gallon tank.




I turned it upside down and using a large, thin paint scraped I carefully taped it down between the frame and the glass. I did this around the entire perimeter. This helped loosed the silicone holding the frame.




I then slowly rocked/worked the frame back and for along the entire edge to help loosen it some more.




I carefully pried (with my hands) the frame off the tank. If I would have been a little more gentle in the chisel and pry process it would have came off in one piece instead of two.




Using a grease pencil I marked a line all around the tank 9" from the bottom.




I cut away and removed the silicone from the marked line up to the top in all 4 corners.




I gently pushed a razor blade through the joint from the top down to the line in all 4 corners. This basically loosened all the corner joints down to the marked line.




Using a glass cutter and straight edge I scored and popped each pane of glass at the marked line. I did the sides 1st since they were "inside" the front/back panes and I needed to pop the glass inward. In the picture the bottom side has already been popped and removed.




Here is the 4 cut pieces. I then cleaned it all up and siliconed the frame back in place.




And finally the finished 7.5 gallon sitting in front of a standard 10 gallon.

So how does that glass cutter thing work? Does it make like an indent then you crack the glass?

haha cool idea! Ive been looking to do the same thing with a acrylic tank and a tablesaw..lol
im lookin for a 100+g tank and turn it into a shallow frag tank. ive seen 100g acrylics for like $50

A glass cutter basically makes a special shaped scratch along the glass then you break the glass towards the opposite side you "scratched" and the break will follow the scratch line perfectly. You do need to make the scratch line across the entire width which is why I started with sides since I then had to pop/break it towards the inside of the tank.

If you have never done it before you can get a cutter, some oil and a thin piece of window glass from Lowes or Home Depot to practice on. Hardest part was keeping the straight edge in place while I ran the cutter along it.

All in all this was a very easy project that turned out great and I ended up with a prefect sized sump (for my situation) for only $13 (cost of 10 gal new) -- I had the cutter and silicone (for reattaching the frame) already.