Ruck RK fan speed

think all you need is a resistor, tbh. But I honestly can't say what specifications. Like I once had a pc fan thing that was a bit much at 100% and a resistor kinda fixed that. Now I'm sure that's heavy duty, but the principle should be the same. But yeah, as BraveheartGenetics says, there are probably options for controller box things, if you just want a simple fix.

Hi mate, I use a device called a varispeed plugin... I plug my fan in to that and plug the varispeed in. I have to set it above half way as like you it seems to sound like its struggling when set too low. It is the better and simplest of tools out there. Nothing wrong with moving a little more air than you need. My fan is triple output of what I need. I hope this helps, feel free to ask me anything else. Good luck and happy growing