The bentonite you get at the pottery place is sodium bentonite, 50 lbs is about $12. That's what most people work with. Calcium Bentonite is available on eBay. It's more expensive at about $32 for 16 lbs shipped. The Calcium in it adds some obvious benefits but since you add calcium Carbonite anyway, You could really substitute and use just Sodium Bentonite.
Calcium Bentonite links 16.5 #'s Calcium BENTONITE Clay KOI ponds & plants WW - eBay (item 260711386448 end time Feb-20-11 21:22:42 PST)
5.5 lb Calcium BENTONITE Clay KOI ponds & plants - eBay (item 250616134654 end time Feb-09-11 16:10:19 PST)
The 16 lb size will last for quite a few tanks.
Aragonite sand is available at coral reef pet shops. (aquarium stores) You are looking for the smallest size of oolitic sand or sugar five aragonite sand. Again, you could just sub regular fine sand but I like the extra calcium and I had a bunch lying around.
Calcium Carbonite. I use the NOW brand with the orange label available at Vitamin Cottage.
The sugar and corn starch are to help in establishing a Biofilm which helps keep the particles, or cubes, of clay separate. It may mold just a little but springtails and isopods will help keep that in check and it will stop pretty quickly.
This recipe would also make a fine background mix although the cornstarch and sugar are probably unneccessary there. You could probably skip the sand too. The calcium may still prove beneficial to frogs but could be skipped. For a background recipe I would sub some of the coco/peat for some ground sphagnum moss to try to encourage future moss growth. My last batch I blenderized some live sphagnum and some live sheet moss in as part of the coco/peat/sphagnum. Time will tell how that works out.
Lay down an inch of Turface before the clay just to cut down on the amount of clay you need. Turface is available at a John Deere Landscaper. Ask for TURFACE or INFIELD CONDITIONER. The grade you want is ALL SPORT PRO
Drainage so far has been excellent. I think the cubes method helps with this. Also, this is my RedArt clay. I do NOT trust a bentonite based clay (but obviously, I like it as an ammendment.) It is important to NEVER go digging around in your moist clay mix. If you need to plant something, either poke the stem down in or even just lay it on top. It will root and eventually grow standing up.
When I plant mine, I like to use a handful or two of ABG mix around the roots of each plant. I put some clay cubes over the ABG.
Remember to use LOTS of leaf litter!!
Sorry if we got a little scattered there, as I said, this is translated from a series of emails.