So this is our first grow and we were 3 weeks into flowering 2 plants under a 400 watt HPS bulb. But then we purchased a 1000 watt set and put that in instead. The thing is when we bought the light they said it was HPS and i believed them. But i was wondering if it isn't an HPS and is a metal halide instead if that would negatively effect the plants? Because now it has been 9 weeks and our buds still look like they need another 2 weeks (they look really good though). Also they have just started to turn yellow and some of the smaller leaves are turning a gnarly brown. Could the light be messing them up if its a MH? It is about 16 inches above them and on a 12/12 cycle. If any one can help it would be awesome.
If it's an HPS bulb then the light it puts out will be an orange color. MH bulbs put out more "normal" looking light.
One reason the leaves may be turning yellow is because of nitrogen deficiencies. Are you giving them ferts and what type?
an mh bulb will put out more uv rays. the hps ithink doesn'y put out any. the plant uses uv and will use it to produce thc which is what u get high off of. so my guess is it will be more potent bud
It is said that MH gives your bud a more complex high to it. But HPS will give you higher yields. Ideal lighting would use both.