Nonetheless, raft systems can be improved dramatically in order to avoid the recirculation of solution and aeration of the roots by mechanical means. This is done in an exceedingly simple way, by placing the raft not directly above the hydroponic solution but a few centimeters above from the solution itself.
The results are incredible. Without any mechanical aeration or movement, this hydroponic system achieves dry weights superior to any floating raft system published in peer reviewed literature. This research was done by horticulturist B. A. Kratky and was published in the year 2005.
So if you are searching for a cheap hydroponic system which can offer you lettuce in high yields with no power usage, this is precisely the way to go. I will publish a post soon showing how this can be done and how you too can enjoy this great system for lettuce cultivation.