about 9000 GALLONS; 12 X 2 0 X 5 X 7.48 gal/cu ft = 8976 gallons
The answer depends on the units used for the measurements. Feet would imply a pool which is only 12 feet long which is very small but metres would imply much too great a great depth.
If rectangular: Lenght X Width X Average Depth X 7.5 = Volume in gallons.
If its an oval pool approx 7800 gallons at full capacity. If its rectangular pool then approx 9000 Gallons.
4400 gallons, or 4,398.24 gallon rounded off.
If rectangular about 21,000 gallons if oval about 16,000 gallons
Cannot be answered with only these measurements. For a rectangular pool, the length, width and depth are needed. For a round pool, the diameter and depth are needed.
Your pond can hold up to 1,885.09 gallons.
Close to 24,000 gal if it is rectangular.
A tank this size can hold a maximum of 3,590.65 US gallons of water.
If rectangular: Lenght X Width X Average Depth X 7.5 = Volume in gallons.
If its an oval pool approx 7800 gallons at full capacity. If its rectangular pool then approx 9000 Gallons.
It depends on the dimensions of the tube, but the question did not provide all of them.
To calculate the gallons you also need the average depth. Then you take lenth X width X average depth = cubic feet of water. cubic feet of water X 7.48 {gallons per cubic foot} = total gallons.
4400 gallons, or 4,398.24 gallon rounded off.
So this is a volume, and if it is a rectangular box or shape, the math is just 40x20x1, which is 800 cubic ft
If rectangular about 21,000 gallons if oval about 16,000 gallons
Gallons do not convert to square feet. However, they do convert to cubic feet: 15,000 gallons converts to about 2000 cubic feet.
The volume enclosed by the tank is equivalent to 3,590.65 gallons (rounded). We have no way of knowing how much water may be in it, or whether it's utterly empty.