Alright I am going to be starting 2 very low light 2.5 gallon standard rectangular tanks. Im pretty sure ill be keeping java fern and maybe some moneywort and some Marimo moss in them. What kind of substrate should i use, how much (as in how many lbs should I buy combined for both 2.5 gallons, and where can I buy it! I keep reading about all this crazy substarte that ive never heard of or seen in store, eco complete... and other stuff i guess. Does it really make a difference? Thank you! Sorry im very new to planted tanks.