Here is an idea that I originally saw in on one Chris Smiths posts (Chris seems to be full of practical and useful ideas, thanks Chris)...Originally I wasn't going to sprout my seeds in a hydroton only media, but after trying this, this past summer with 50 or 60 different plants (from various leafy green types, to tomatoes and peppers), I saw that it works great. Every seed I planted sprouted as good or even better than in all the different cocco coir, vermiculite, perlite, worm casting, large hydroton, small hydroton combinations that I also tried. (I think I tried like 20 combinations in all).
It's much less time consuming and there's no vermiculite or coir to float out of the net pots and into an AP system. As this could build up and potentially cause problems (with fish gills, or anaerobic sludge at the bottom of troughs, additional solids clogging up my media beds in the hybrid system etc)...
I've filled the 'under the table' spouting area which I've described in my previous blog, to 1/4 capacity. Romaine, Red Summer Crisp, and Spinach. I've covered up the Spinach from the light. Lettuce is one of the few plants where light will act as a trigger for seeds to start sprouting, so I never bother putting them in a dark place.