1) I recently got an orange clarkii and I was wondering if adding calcium to the water would help him grow and stay healthier. I've head about others doing this and I'm wondering if there really is a benefit doing so.
For any freshwater inverts, making sure they have enough calcium is important. If your water is very hard (GH hardness, not KH hardness) then extra supplementation is probably unnecessary. If your water is very soft, then adding a little bit of calcium certainly wouldn't hurt and may even be a good idea.
Another thing to keep in mind, though, is diet is a big source of calcium for inverts as well. Regularly feeding your crays something like
Hikari Crab Cuisine, which is enriched with extra calcium specifically for crabs, crayfish etc., is a good idea. You don't have to feed it every day, but giving your cray a couple of pellets every few days will go a long way towards being sure your cray is getting the calcium it needs. Another good calcium-laced food option would be Ken's Veggie Sticks with Calcium, which you can get from
Ken's Fish. (Note there is also a regular veggie sticks without extra calcium, so if you are buying for an invert, be sure to choose the veggie sticks that explicitly say "With Calcium," which are the last ones listed on that page.)
2) Does plant food supplements (ie Nutrafin Plant Gro) harm shrimp? I noticed it has trace copper in it and I know that is bad for inverts.
In general, you want to be very cautious about fertilizing shrimp tanks. Any fert that has copper in it should be used extraordinarily sparingly, and only at doses far far smaller than the "recommended" dose on the label. For example, I use Flouish Comprehensive to dose trace elements, but when I dose it I put in about half of the amount the label says, and rather than dose 1-2 times per week as the label says, I probably dose only once every 6 weeks or so. Ideally, if you can get away with not dosing at all in a shrimp tank, that is the ideal situation.
