4400 gallons, or 4,398.24 gallon rounded off.
Multiply all three dimensions to get the volume in cubic feet. Then multiply that product by 7.48 to convert to gallons.
17,953.2 gallons
(21 x 18 x 9) = 3,402 cubic feet = 126 cubic yards = about 25,448.73 gallons
Assuming that your 8' pool has a shallow end then you have an average depth of 4'. Apporx. 7200 gal.
If this is a round pool 18 feet across and you fill it with 4 feet of water, it contains 7,646 gallons of water.
Multiply all three dimensions to get the volume in cubic feet. Then multiply that product by 7.48 to convert to gallons.
615,142 gallons of water are needed to fill this cylinder.
17,953.2 gallons
(21 x 18 x 9) = 3,402 cubic feet = 126 cubic yards = about 25,448.73 gallons
Close to 24,000 gal if it is rectangular.
Assuming that your 8' pool has a shallow end then you have an average depth of 4'. Apporx. 7200 gal.
It will take 5,104.1 gallons of water to fill this cylinder.
If this is a round pool 18 feet across and you fill it with 4 feet of water, it contains 7,646 gallons of water.
An 18-foot round pool with 3 feet of water contains 5,734.8 gallons of water. If you fill it to 4 feet deep it increases to 7,646 gallons of water.
It would require 2,937.6 US gallons of water to fill the pipe.
If you fill it to four feet deep, the total is 10,408 gallons of water.
A pool this size with an average depth of 16 feet requires 462,560 gallons of water to fill it to the top.