Tank laying down

That's me inside the tank. It's a 300 gallon system measured internally, minus the water displacement of the overflow and the fact that I'll run it about 1/2" lower than the top because of the overflow. I'm 5'9" (5'9.5" on a tall day), and my toes are touching the bottom of the tank. It's a bit nasty in here as there's salt crusted all over it from some rock that I was storing in the tank, so my back is really dirty.