Yes decreased wattage equals decreased buds. 18 inches should be safe for most plants when you're running the 600 HPS. If the temperature of your tent is too high then you don't have any choice other than to dim. Assuming you've done all the other stuff with proper extraction excetera?
A fan blowing directly across the top of the plants can help. Could you get some picks? could be lots of things going on.
@jingo,sorry misunderstood your asking for pics. I sent new pics of plants when maybe you wanted pics of set up...dunno but here are the pics of tent






First pic shows carbon-ducting-inline fan(240cfm 6")-light-ducting vented out window. The next pic is of 6" clip fan blowing across the tops from the left front corner. The next pic same just blowing from the back right. Next pic is of a 4" fan blowing up the widows skirt. The next pic is of a 10" blowing the lower cooler air up the corner of tent.
I find that I can keep ballast at full and the temp at 77-79 with the front of tent totally open???
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