Also stefblac, remember when you are trying to maximize your growing space. If you are using the N.F.T. method, one key thing to remember the more plants you have in your "line" like if you were using a "gutter" drain method. After the water passes over the roots of so many plants in the "line", the oxygen level will deplete due to the first plants in line absorbing the oxygen. Not a real big deal if you only have 10 or 15 plants. If you have like 25 plus for example, you may want to consider aerating your nurtient solution with an airstone. It will help make sure that all of your plants recieve plenty of oxygenated water/nutrient solution.

Thanks for the info guys, much appreciated

Stefan