Monster, that is an awesome looking paludarium! If my terrarium was made to hold water, I'd definitely do something like that. At least I've found a massive tupperware container for water (13" by 9" by 4-1/2", there abouts). And! If my toadies seem to be enjoying the water, I can always get more, stick 'em around the terrarium.
Quick question about a bioactive substrate! Is there a way to, like, make my own? Out of Eco Earth? I've already got that stuff, and it looks like it'd be kinda pricey buy a bunch of the ABG stuff. Could I mix one bag of Josh's Frog's ABG mix (4qts or 16cups or 3.79L) with the Eco Earth?