I did a little reading on kitty litter and koi clay. Most of what's out there is forum chat, but I found a couple of articles worth reading.
This article explains the different types of clay and what they do for the water and the fish.
This one is a sales pitch but presents some interesting information.
Both pure clay kitty litter and Koi clay are Montmorillonite = bentonite clay. Such clay is found and mined in many places. Koi clay provides two different benefits. It provides a rich supply of mineral nutrients for your koi or goldies. This contributes to general health and particularly improves scales and color. (Some people eat clay for minerals as well.) It seems quite likely to me that the pricey koi clay has a better selection of mineral nutrients than Special Kitty, since clay from different locations will have different minor minerals, and some are just going to be better.
The other value is water purification. Clay particles can bind all sorts of impurities in the water. When you put in clay, the water gets cloudy from the suspended clay particles. When these settle out the water clarifies -- often dramatically. I would guess that Special Kitty performs this function as well as does Koi clay.
Lots of people say that clay has cleared up algae. I haven't seen any controlled studies, but it's probably true. Nobody seems to know why. The best suggestion I've seen is that the clay binds to the algae and that damages it in some way.
This article explains the different types of clay and what they do for the water and the fish.
This one is a sales pitch but presents some interesting information.
Both pure clay kitty litter and Koi clay are Montmorillonite = bentonite clay. Such clay is found and mined in many places. Koi clay provides two different benefits. It provides a rich supply of mineral nutrients for your koi or goldies. This contributes to general health and particularly improves scales and color. (Some people eat clay for minerals as well.) It seems quite likely to me that the pricey koi clay has a better selection of mineral nutrients than Special Kitty, since clay from different locations will have different minor minerals, and some are just going to be better.
The other value is water purification. Clay particles can bind all sorts of impurities in the water. When you put in clay, the water gets cloudy from the suspended clay particles. When these settle out the water clarifies -- often dramatically. I would guess that Special Kitty performs this function as well as does Koi clay.
Lots of people say that clay has cleared up algae. I haven't seen any controlled studies, but it's probably true. Nobody seems to know why. The best suggestion I've seen is that the clay binds to the algae and that damages it in some way.