I have a 30 gallon long that I want to have different tiers if you will that will have a waterfall at the very top, going into a pool of water, that will go down a river then fall into another pool of water, that will then travel down another river into the main pool of water. How would be the best way to make this effect happen? GSF and carve the river out of it? Just dont know how I'm going to make the different tiers yet any suggestions would be great. What pump/filter would you recommend to get the waterfall going to would be helpful. Thanks all!