I was doing a little research online, and found that epsom salt raises gh without affecting kh or ph! Too cheap to buy a legit gh booster so I might give this a try. Has anyone done so? Does it have bad side affects that might annoy shrimp?
You won't find pure calcium (reacts in air). The cheapest would be to just buy the gh booster or separate chemicals. If you have calcium vitamins laying around they might work depending on their make-up but they are more expensive.
calcium vitamins use oyster shell, otherwise known as calcium carbonate (basically will raise GH, KH and pH)
It would be best to buy a product that was designed to be used with shrimp, it will have the optimal ratio of magnesium and calcium and (depending on the product) should not have any effect on the KH or pH.