Using this method we started with regular pea gravel from the garden center. The gravel is perfect because it wont absorb or hold water and has so many little crevices, nooks, and crannies between each pebble that roots can easily spread. Because the gravel. Is dirty, we put it in buckets and rinsed it with a garden hose to remove the dirt.
The lesson learned is that gravel makes a great grow media, but even when you think it is clean...it is not. We put the gravel in the grow bed and waited for the first flood and drain cycle to see if we had the water level correct. The water level was correct but the gravel wasnt as clean as we thought. The dirt fouled the water so bad that the first set of fish pretty much died within 24 hours. The survivors were temporarily released into the pond in the front yard. Good thing that we conducted the test with feeder goldfish!
Lessons learned. Gravel is a great grow media. Gravel must be thoroughly washed until all the water runs clean. Always conduct tests with feeder goldfish.
Oh, by the way...some pepper plants and a green onion are the test plants to see how different root systems interact with gravel as a grow media. They are loving it!
