Planted Tank Enthusiast
Join Date: Oct 2008
Location: Arapahoe County, Colorado
All LECA (Lightweight Expanded Clay Aggregates) will float. There is about a dozen different names for essentially the same product (hydroton, hydroballs, growstones, etc) some are diff shape and the like, but they're all pretty identical beyond cosmetics.
I think it sounds like a great idea to experiment w/, why not? Once they've been soaked for some time, they'll all sink eventually. I do wonder whether or not they will retain their open pores w/ whatev nutes you add to load em, the pressure of the water, plus whatever it is you plan to cap them w/. You may lose that porous quality about them and end up with a clogged, nutrient-filled, and possibly anaerobic tank bottom. I think the anaerobic option is a whole lot less likely given that sometimes even peat moss is placed at the bottom and capped.
Anyways, if you do give it a shot please let us know how it goes.