You did a great job on your build but just a tip for your next build:
Use the exact same plan just add legs under the frame the tank sits on. In your design, by screwing the legs to the sides of the frame, you hang all the load on the screws. You might get away with it for a 75 gallon but larger tanks could snap the screws.
enough screws can actually support just as much weight as the 2x4's themselves as long as the hardware was appropriate for the job meaning long enough and thick enough with enough (quantity) per leg, deckscrew will hold up just as well as the wood.
(carpenter 16 years)
...based on the pictures, there are about 16 screws holding the top frame to the legs (didn't see any in the middle legs), each screw should hold about 300lbs based on the manufacturers claims (the OP is a carpenter, so he knows what to pick.) This estimates to 4800lbs.
You did a great job on your build but just a tip for your next build:
Use the exact same plan just add legs under the frame the tank sits on. In your design, by screwing the legs to the sides of the frame, you hang all the load on the screws. You might get away with it for a 75 gallon but larger tanks could snap the screws.
I agree, but I do like the visual of this stand. I've done stands both ways. Without the upright supports under the frame, I used 1/4" threaded rods through the legs and into the top frame so it could never let go. Overkill.