You can use a small screwdriver to dim I had it all the way down. I just think I was to close. Thanks I'll download it.Does it have a dimmer ? Also what you can try is download an app to test the lux and ppfd you are getting. Just know that it isnt as accurate as an real lux meter . Dont try to test the blurple but try it on the maxisun. Blurpies and lux meters are not a good combo.