Newbie Medical Grower

Hello all, just wondering if someone could tell me if 4 1000w HPS's is enough lighting for flowering in a 9.5 X 9 room with 8 foot ceilings? I have 20 Dutch Treat plants in 3 gallon buckets using soil. I have 2 10" vortex fans w/carbon filter, using digital ballasts. I was wondering if it would be better to use 5 lights???? I am a medical marijuana patient so the cost of electricity doesn't matter. I also have no problems at all with heat right now as it is winter where i am lol.

its never a bad idea to have more lights as long as heat isnt an issue. But the 4 lights you have should do the trick

4 is plenty for 81 sq feet. The height of the ceiling doesn't really matter. You might not have a heat problem now but you might later. 4 will make a lot of heat!