======================================sea_dragon:what were the demsions of the 250 gal tank?......yeah i am going to get a boat at the end of the year.. so get ready...lol... i want to build a 300 gallon.... but i want to learn more about aquariums before i get into that though....
Don't have the exact numbers anymore. Built it from scratch in 1973. Lenthwise it was well over 5', height was about 24" and depth was about the same. Reason I know about the capacity is that it took 5 of the 50 gallon plastic garbage cans full of seawater to fill it. It was an experiment that went "right", after many successful smaller aquariums. It was too big to mix the seawater and I had access to a boat (and we both had aquariums) so we went way out into the gulf stream and collected our water for initial filling and water changes.
One suggestion is that you keep your depth and height around the 24" level for access. Length is where you can pick up your extra volume. Another thing ...with the longer aquariums you need to have braces running from front to back to control the bowing of the glass. I used (if I remember correctly) 1/2" tempered glass.
I learned more about aquariums, salt water chemistry, fish collection and fish diseases than I would have in a lifetime with store bought versions. It was a good time in my life. Survived 3 years in the military (US Army 1968 - 1971), moved to south Florida and had returned to college. Had lots of time on my hands and had discovered SCUBA diving. My former state of residence (Ohio) was giving a $500 bonus to Viet Nam era vets and I told myself that if I actually got that check I'd use it to build my aquarium. It took me EVERY penny of that check, and then some, and that was back in the early 70's.
Enjoy your plans ...
'Slogger