There we go, Nice idea with the cooler.... Think outside the box.... A coolder may work, you could pump the water up from the bottom to if ihas a place for water to drain.... I always thought about finding something that farmers use to water cattle in or something.... Something big enough to hold a good amount of water but not too big to fit under the tank....
No matter how hard i tried, my water volume was never big enough for me.... Kinda like tank size... I always want more....