In calcite lime stone or calcium carbonate you naturally have an abundance of sodium carbonate and sodium bicarbonate. All three have a buffer capacity. They will raise alkalinity and stabilize your PH.
I do expect you will not have any problem with adding the calcium carbonate to the water after the fish are in the pond. Rain will have a very big effect on the water.
Big thing they will say to look for is the CCE % but that is just a chemical rating and not the true content of the product. It will give you the rating equivalent of pure calcium carbonate NOT the % of calcium carbonate.
Dolomite lime is very easy to get a high CCE % but that is because of the magnesium in the product. Yes for fish production magnesium is needed but not in the volume ag lime can provide. Mag is still a micro nutrient.
As I understand it, the magnesium is used by plants and animals, but it's largest benefit in our ponds is that it also binds to the solidified calcium ions, preventing calcium from precipitating out and to keep water super-saturated with the calcium.....increasing the total buffer capacity. Correct? (over-simplified, I'm sure)
