I should mention that I can bring the light really close too the top of the plants if I wanted too! but it's a fresh batch of plants I just put into flowering and I like to gradually bring the light closer to the plants,not because of the heat or anything lol because there isn't any just so the plants can get use to such a strong blast of light a 1000watter can give!......if I wanted to I could have the plants touch the glass tube without any effect to them....