Hydrotron floats if it is not holding any water. Not only do you need to rinse Hydrot but also soak. I run E&F in 2 seperate cabs and only have maybe a half dozen pebbles that float. No pot is needed in your E&F tray. put a layer of pebbles then you RW cube and bury the cube about 2/3 up. only need to flood to top of tron, NOT to top of cube. If you constantly flood to top of RW you flirt with stem rot issuses. working on my 2nd year of doing the same exact thing and it works.