There are many companys in the waterfall and pond industry that manufacture the “eco systems” needed to filter the water in your feature.  However be aware that some of these pond products are not always as good as they may seem.  One of the largest players in the waterfall industry actually has one of the worst records on product quality.  I legally cannot say the name, but if you do enough research on water features, you can find out which one I am talking about.  I have had over 40 pumps fail within a year of installation.  I have had pond auto fill units stick on over 40% installed.  The screws and face plate receivers for the Bio fall and Skimmer filter units were made with ALUMINUM.  These aluminum parts were pennies cheaper than stainless steel, but to make a better profit they were used.  Within as soon as 2 years in fresh, filtered water, these parts literally dissolved away.  This problem is nation wide and has been hurting many contractors. 

This story is not to scare you away from building a waterfall, but rather to inform you of the best product to use.  I have been installing the “Atlantic” eco systems for over 3 years now and have no problems with any of their water feature products at all.  They use all stainless steel parts, their filter units are made with a much stronger plastic, no pumps have failed for me yet, and the auto fills have had a 100% success rate.  This company also makes all of their products here in the United States, unlike many other companies.  These products are also much cheaper than other manufacturers.  So in conclusion to my rant here, be aware, and do the research before building a water feature.  Stick with quality products made locally and your project will be a success.