I ordered substrate from aquariumplants.com--Igot the black--I have a 20 G long and they sent me 3 gallons.  I started putting it in my tank and after about 2 gallons, it seemed too deep.  How deep should the substrate be.  I will have live plants over about 2/3rds of the tank. They will be low light plants--cryps java ferns  and saggitaria. l
				
			 
	 
	 
		  
 
		 
 
		