As long as the height you are pumping to is not too high I don't really see a problem.
Can't you find a way to mount a large container in the same room as your fish tank where it will be above the level of the tank. Have a drain at the bottom and connect your hose onto there. As easy as opening and closing the tap. Just fill it up straight from the tap and leave to age.
Can't you find a way to mount a large container in the same room as your fish tank where it will be above the level of the tank. Have a drain at the bottom and connect your hose onto there. As easy as opening and closing the tap. Just fill it up straight from the tap and leave to age.