Light reflection to the main stem where the first secondaries will come out. If used from your current plant age, it will help your plant grow wide as much as tall.

Ideally white marble as it is very non pourous and thus wont hold water or soak it away from your topsoil. Non pourous will also prevent ground mold.

It is also easy to clean which you will have to do once in a while especially if you grace your plants with some dark bat guano.

Light relection is in reality as much as important as anything. Light should be bounced until absorbed by green foilage as much as possible. I cannot stress this enuff. Your light is either absorbed by green plant matter or some other substance.

Eliminate the light loss due to the non plant materials as much as you can. Every single bit helps.

You grow room with lights should be blindingly bright. It should look like the second coming of Christ with light

Any and everything you can do to measure up to that standard should be done and will help you achieve remarkable growth up to 28 days with floro / cfls.

Read and look at 9ski9's HARDDONA UPDATE thread to see the transition from seedling to current.

I think you might learn a whole lot...just ignore all the bullshit posts....we had a lot of them