I've been told that when logical mental reasoning and physics clash, go with physics, so here is my dilemma. When I built my home I wanted a large aquarium, 1,000 gallon or more. I talked to a public aquarium operator in Dallas TX and was told 3/4" glass was the thickest glass publicly available. I asked if the glass would hold for a 48 x 96 front glass and was told it wouldn't. I knew about an aquarium that was 38 x 96 x 18 with 3/4 glass that was fine. I decided to go with 38 x 96 x 72 (1,138 gallon, 9,445 pounds of water). After a bit of research I found front to back depth didn't effect the pressure on the front glass, only height. I calculated the water pressure on the front glass to be 2,626 pounds of force. I built the tank and as I started filling it a straight edge showed it was bulging in the middle after it was only 1/4 full. I kept going for the entire 1,138 gallons and it held up with a significant bulging.
Lets say that the front glass was simply held against a rubber seal by the 2,626 pounds of pressure alone, it would take 26 men pushing with over 100 lbs each the break the glass loose. We're probably all in agreement so far but here is where the laws of physics and logical thinking go separate ways. Now lets move the back glass forward until the 72" is .002" between front and back glasses, it will only take a 1/4 pint now to fill it. Will the 4 ounces of water actually create a force of 2,626 pounds on the front glass? Will it take 26 men, each pushing with a push of 100 pounds, to break the seal? Will the tiny weight of water bend the 3/4" glass the same amount as 1,138 gallons? A sight level tube placed anywhere on the front glass will show the pressure in the area it is installed in to have exactly the pressure to force the column of water in the tube to water level, I can accept that, but 4 oz of water creating 2,626 pounds of force somehow gives me trouble.
Lets say that the front glass was simply held against a rubber seal by the 2,626 pounds of pressure alone, it would take 26 men pushing with over 100 lbs each the break the glass loose. We're probably all in agreement so far but here is where the laws of physics and logical thinking go separate ways. Now lets move the back glass forward until the 72" is .002" between front and back glasses, it will only take a 1/4 pint now to fill it. Will the 4 ounces of water actually create a force of 2,626 pounds on the front glass? Will it take 26 men, each pushing with a push of 100 pounds, to break the seal? Will the tiny weight of water bend the 3/4" glass the same amount as 1,138 gallons? A sight level tube placed anywhere on the front glass will show the pressure in the area it is installed in to have exactly the pressure to force the column of water in the tube to water level, I can accept that, but 4 oz of water creating 2,626 pounds of force somehow gives me trouble.