I meant that no matter how well your guys cleaned that gravel, you will have silt from the gravel as soon as you start the water flow. It wont last long, but thats a lot of gravel, so expect some dirty water on start-up. I'm sure it will be plenty clean after that with all the filtration you have going. I love the idea! I'm kinda confused, though... Are you going to use aquatic plants or regular plants? I dont think it will make a difference, just curious.