1 until they're in bloom probably, I use a similar tower fan in one of my tents. 2 tends to give me wind burn, I found that 2 fans in opposite corners has always given me great circulation and kept my ladies happy.I have a tower fan inside at what speed would you say i should put it on. 1,2,3? I dont want to go crazy blowing these ladies around
Also if you're not properly ph'ing your water youre going to run into some issues there too. I would also suggest the ph pen first and ppm pen second. You won't need the ppm pen until you start feeding it heavy in flower anyways really.