I have done experiments with soil mixtures, and let me tell you, it makes a huge difference in the growth of a plant. i currently have one plant that is in a similar mixture of soil that you have and i swear it looks like a lowrider. it is not though. from my experirence you should have almost 40% peat moss to get alot of growth. finially different people swear by different growing methods, and you can use whatever you want. As for my experiment i have came to the conclusion that if the soil is to compact and doesnt retain water well then growing will be stunted and it will take alot longer to get the desired growth.