HI,

I have suffered this problem myself along with blight which occurs when there is bacteria in the water supply or the humidity is too high. I solved it by buying an led grow light with ultra violet leds fitted as this kills all bacteria and bug and solved my problems. You can buy them form various place but i found the best one was High Quality LED Grow Lights High Growth High Yield as they are professional and know what they are talking about. I bought a 300 watt supanova but best to call them as they will advise you what is best for you. I hope this helps as it has certainly cured my problems.