Don't know if it makes a difference but I have newts. I use fresh water caribsea super natural aquarium sand, I have raised a few larvae and juvenile on it with no problems. I have 4 larvae in my cycled shrimp tank right now, It has sand Caribsea sand they have been in there since I found them in mom and dad's aquarium that has sand to. They've been thriving in my shrimp tank for over a month now. Pretty sure they only have one size it's very small, I've seen juvenile newts under a inch spit it out when eating.