What is a good way to clean calcium/lime from an aquarium?  

I agree, CLR or Limeaway are both good products to try. We used to have a large aquarium and I had to clean it now and then. After emptying the aquarium I used the Limeaway on the glass. I never tried it on any of the plastic parts. You have to make sure that you get it all rinsed off, so that when you fill the aqaurium back up, there is no residue in the water that could kill the fish! Good luck!

Thanks. I was thinking of those two products. I wondered if they would do the trick. I sure dont want to spend hours trying to clean it like I did yesterday. We are going to take our time with it cause I need to clean the whole thing including all the tubes and filters and pumps. We won't be putting any fish in it until we can get it all cleaned up and safe to put the fish in.

Thanks for your suggestions. Ultimately what you suggested is what I did. What I didn't like was the "elbowwork" I had to do on this second hand tank. Oh well, that is what I get for trying to help out the husband. Thanks for your response.