I can handle either. I just need the based dimensions of the 75 and 90 gal. I was hoping to find someone local to me that was getting rid of one.get a 90 if you don't care about it being 200 pounds heavier and 3 inches taller, make sure you get a suitable stand as some won't work with such weight, and 90 gallons is a lot of water, make sure you know what to do if something springs a leak, because that could be the difference between a minor mess-up to a "my floor is destroyed"