WWgrower, a 400w HPS without an air-cooled hood should be 15 inches above the plant top to keep from burning the plants.

When you add Kool Bloom, you need to cut down on your basic nutes, so the FloraNova should be less than 10ml/gallon, maybe 5-7ml.

As plants flower, and get taller, the lower leaves get less light, and are used by the plant, so naturally yellow and die. At this point, you can only let your plants mature as best they can. Give them more fresh air, and more circulation, because in late flowering they need it.

HTH

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