Ok, the light is 400 HPS. I have it at about 250mm away from plants. The 2 plants that are actually mainly affected are 300mm away. Temp in the room is roughly 23 deg. Fan is on the light to keep cool.

The water temp is 23 deg.

EC is exactly 1.2

Just before this happened i was feeding for 15 minutes once an hour and not feeding at night.
I have since moved feeding to 15 minutes every 4 hours now.
I dumped the water yesterday as originally it was reading an EC of 1.4 and i had Silikamajic Silica in the mix.

Should i dump the water again and run no nutrients at all for a week??


I had the water feeder of each plant going directly onto the rockwool but have now moved them all slightly away so only the root area will get feed.

I will take some photos now of set etc