I've used Gravity and Purple Maxx with no problems. I grow in Happy Frog, keep my temps between 76 and 78 and pH my water to 6.3. I use Gravity and Purple Maxx together for just one(1) feeding three weeks before harvest. I add 1 tsp. each of Gravity and Purple Maxx to half strength nutrient water. I also raise my HPS about 12 inches for a few days. One thing tho, don't use these products if your plants are not healthy or if they're stressed. Mark your calendar so you know when it's three weeks before harvest. If your plants are needing to be watered/feed every three days then three days before watering with Gravity and Purple Maxx, water with plain water.

A couple of things to keep your girls healthy. If you grow in potting soil in containers, water from-the-bottom. Plants release their waste material in the top layers of the soil so if you water from the top you're flushing the waste to the roots. Make sure to never overwater. Use the Lift the Pot method and you will never overwater.