Thanks for the pictures and I can see why you can only place 9 gallons in the tank to avoid the siphoning issues.
By the way, where is the water level in your overflow, most people are recommending that you have it about 1/2 - 1 inch below the emergency drain pipe.
By the way, where is the water level in your overflow, most people are recommending that you have it about 1/2 - 1 inch below the emergency drain pipe.