Hey there so first with the rh/temp I'm constantly hearing about vpd(vapor pressure deficit) and that's essentially what that is heat and humidity. I was always thinking that high humidity in veg is great of coarse, the swampier the better, but flowering I'd always heard around 50% and a variety of temps but typically 70 degrees F. But now I'm hearing more about keeping things around 75 heat and 70% humidty is a good range to be...something about keeping things consistent is always a plus so if you choose lower rh for fear of pm etc then try to at least keep it constant. The fluctuation is sometimes what will cause more damage than running a higher rh or temp.
With the ppm i believe it goes 0(RO water/distilled) -400(ive heard 700 also) being very hard water, and then as you add nutrients it will increase beyond that. If you have a tds meter with your ph pen that will check your plain water(tap or otherwise). Your nutrient water should fall somewhere in the 400-800 range, but that'll all depend upon your original water reading. You could increase the ppm either by using tap water versus r.o or i suppose by increasing the nutrients, basically use nutrient rich water. Science! Isn't it amazing and exhausting all at the same time? 😊