I was given a tank around 70ish gallons by a coworker and needed a stand so I went the cheap route and got cinder block. the tank measures 36x18x25. My question is about support. I got cinder block that measures 15 5/8x7 5/8x7 5/8. Now i know how i want to stack them but the question lies in the 15 5/8 part. I plan on just supporting the two ends on each side by three stacked cinder blocks. Since the tank measures just over 18" with plastic will this due? There would be about 1.5" gap in front and back . i didn't want to buy more cinder block because the spot I have for the tank doesn't allow for much more. Any info is much appreciated.