Thought I'd post a little update on the sand system before I add in 15 tilapia to the mix. So, the growth that you see is the product of 2 good-sized goldfish - that's it. I've seen good growth in the tomatoes, and all of my seeds have germinated. I will say, though, that it seems like the seeds may have taken longer to germinate than they did in my hydroton system. Could be that the weather is the major factor in that, though, as it's been exceptionally cool and rainy this spring.
Veggies include tomatoes, green beans, edamame, cucumber, yellow squash, sweet pepper, and some basil starting to come up.
Top shot shows the grow bed when the water starts collecting. Bottom shows what it looks like after I poke a few holes in the sand with 1/2" PVC pipe. Many claim that I won't be able to keep this up for long - that the sand will compact and clog and eventually stop draining well. Maybe... but for now, things are fine with the occasional hole poking.
All in all, I'm happy so far with the sand system. Having to poke some holes into the sand to help with drainage isn't that big of a deal work-wise, but the fact that it requires any extra effort puts it at a disadvantage to my hydroton system. It will be interesting to see how the drainage fairs over time. I think most people think it will get clogged and basically crap out. I sure hope that doesn't happen!