Personally I am growing HC in a small 2.5g tank with ADA Aquasoil Amazonia donated from a friend. It is growing beautifully. I am not sure however how important of a role the soil actually plays out. Do you have a smaller tank that you can test out your soil with HC? That would be my recommendation as I'm sure you have plenty of it anyway. Don't worry, within a couple of days you will notice if the HC is growing or not. Check off the most important aspects though. Light, light cycle, keeping the tank covered and that the soil is covered in water (the soil, not the HC) - Look through the forum threads, there are plenty of guys here who have grown HC emersed into gorgeous carpets in tanks ranging from 2g all the way to 50+
Best of luck!