- I'm attracted to rafts because you can look at the roots, easily move plants, and keep a production line moving , but with the right media an Ebb & Flow system will over time be the most economical.
Heavy crushed gravel is an initially cheap media, but it makes transplanting difficult, whereas a light soft media allows plants to be inserted even more easily than a Net Pot. Apparently pumice is not readily available to everyone, but my recent experience with it has changed my opinion of media beds. There are other options such as expanded shale or possibly lava rock that provide a similar benefit.
The complexity of a bell siphon can also be avoided by using an Ebb & Flow design rather than a Flood & Drain method. But it is the utility cost savings that makes this a very attractive option. Running a pump 24/7 becomes expensive and adds heavily to the cost of the product produced. $4.00 tomatoes are hard to swallow.
The pumice has not worked out as well asI had imagined.It is prone to packing and clogging. 3/4" gravel or better yet expanded shale are my first choices. Media like Hydroton are also good choices if you can afford it.
The settling filter pictured above shows a blue filter. This worked well until the fish grew and over whelmed the filter pad which then required cleaning everyday. For a better solution please read these posts.
Filtering Poo with Continous Flow Media Bed