well I do know that the aquasoil, has NO benefits, no nutrents, it looks ok, YES it is very light, barley holds down a stem plant, you would have to use another sub on top of it, ir mixed with it , You can go to bigals.com and usually they sell some of the eco-complete pretty cheap, I got mine on clearance and it was actually 10.00 less than driving 3 miles to my lfs. ! but I am not sure if its still on sale, you can also try that fish store that pet place .com, lol,., they have wonderful speacials and deals all the time !!
the aquasoil does NOT affect your ph as far as I know, it may lower it and I have NO proof of that , .. but the sand sounds neat, I wish I had some of that ! I am actually about to set up a 90 , and I want a riverbed in the middle, I am thinking pool filter sand, but I may go crazy and get some purple sand if I find its ok to use...!! LOL,
OK, as far as in deep, I will say about 2 in , nomatter what size tank,. now if you decide on the aquasoil, you may wanna go ahead and do almost 3, because it doesent take much !! I would say one bag should be enough for your 50- , I know sounds crazy but you will see !! but add somthing like the pea gravel to make it heavier, the corys will love the sand, try and make a all sand corner, you can research how people do that , just do a search in the forums!! good luck !! and rember post everything you do and pics!! we like to watch !! ~~~~~~~~~~~~~~~~starla