how do you remove real hard calcium built up on a water fall?
Answers:
Go to a pool store and get a bottle of "scale-be-gone". They might have to order it. It's a gel so it stays on vertical walls. Paint it on and let it stop bubbling. Then rinse while scrubbing with a nylon scrubber. Might take a couple applications. CAUTION: this stuff will bite you if you get it on your hands. Wear protective clothing.
Other answers:
vinegar is a safe product if you don't have fish or plants.
vinegar is a safe product if you don't have fish or plants.
You may want to try vinegar. That helps break down the mineral deposits.
Try scrubbing it with CLR
CLR as long as there are no animals in the water and no one is drinking out of it. CLR can be bought at Home Depot, Lowes, or WalMart.
CLR
Calcium Lime Remover