How is my set up??

We just bought a 400w MH conversion bulb today and the 400w HPS ballast, and shade to go with it, we have a 4' hydro harvest garden, and 15-30-15, as well as 20-20-20 ferts, also the nutrient solutions that came with the hydro harvest, some ph tests kits, and the air pump for the water.

How often do i need to change the water in the resevoir, and how close should i keep the bulb to the plants? Do i leave the air pump on 24/0?

Also, should i put a fan blowing over the plants? and lastly, does lining the walls with aluminum foil help much? We have 8 plants just sprouting in the garden now.

There are posts just like yours all over these boards.
Read them as ppl get very tired of ppl who can,t be bothered to get a book or read other threads.
:)