i am going to buy a tank in the next few weeks, right now im set about 20 gallons. this tank will be fresh water and i want to have plants as well as fish. my questions are: is there a tank dimension that is more popular or cheaper to find lights for in this size? what are some good brands/types of filters (as reasonably priced as possible, with good quality components)? is making my own filter a reasonable idea for a tank this small? what brands/types of lighting are best for light/fish combos? i found a tank that has similar dimensions WxD, but is considerably taller than the others. i think it was the same dimension as a 20 gal, but twice as tall. is this wasted space for my fish and plants? my hope is to get a tank from craigslist or used and build from that, but i may go new. i would rather get it sooner than later but am more worried about cost of startup. any ideas or suggestions are greatly appreciated.