oh also, i couldn't find this on the substarte cal;culater, about how many bags should i buy to get a 2 inch thickness of substrate, my tank is 36 inches by 12 inches by 17 inches...if u could give me an estimate that would be appreciated... =)
I strongly advise against all rock or large stone substrates.
a lot of food and debris gets stuck between the stones and makes
a mess as it biodegrades, then fouls the water when disturbed.
pretty much any substrate with stones larger than 12mm
does a poor job of supporting live plants.
If you must get large stones, go with an undergravel filter plate and lift tube. they will help remove the worst of the debris buildup, however this is still not a desirable medium for plants. you could go with tough root plants like Swords, or rhizome based Anubias, as long as you are planning a Low Light tank. Another idea is to do a Hillstream tank where large stones with fast running water can make a unique aqua-scape, but with limited plant potential, and specialized fish selection. This is just my experienced based opinion, I'd wait for others to chime in before rethinking your scape.