And here I was thinking my water was bad! I wish I could remember where I saw the posts on getting the KH and the GH to equal. It must have been some of the very last things I've read on the subject - I know that because I've remembered them, lol. I usually only remember the most recent things I read. It's very nice to find out that somehow I've stumbled blindly onto something good in my tank - I'll start testing my others, as well as my tap just for kicks.
As far as feeding the snails, I try. I bought some sinking veggie sticks with added calcium, but the first time I put them in the tank the Buenos Aires and Columbian tetras ate 90% of it. They swam around like little gangsters with cigars until the sticks softened enough to eat. (I admit I was worried about choking). I fed again yesterday and I actually saw snails eating the sticks - the fish only got about 1/2 of it that time. But the fish pick them off the bottom, even pushing a snail off to get the stick. I'm feeding the fish veggies several times a week now, so it's not that they are starved for greens...
The sticks are rather expensive when the fish eat them so fast - if it was just the snails I could justify the cost. I'd like to learn to make my own. I did break up small pieces of the cuttlebone hoping the snails will cruise it once it sinks - and I put a big piece in the filter - I may remove it, I'll see how it effects the water first.
Ok, well I'm not going to tinker with the water in that tank now that I have more info and I'm starting to understand these relationships ~ thank you for all your help!