dead load is just a load that doesn't move. I asked about height because 6x2x3 is 50% more water than 6x2x2. now to see if Dr. Dad has a quick answer. He usually has more questions...I'll have to measure when I get home, but since it looks almost the same height as the floor joists I would venture to say its a 8".
I was thinking max height for the tank would be 24" no matter what size length I go. Framer also said the weight was calculated from my info to be 40 pounds per square or 10 pounds per dead load but wasn't sure exactly what that meant as it relates to my situation. Does that sound right considering where in the room I want it to go? It's not like I want it in the middle of the 13' span.
edit to add: husband says its 8" inches