Pro Mix HP is a great product to use under low heat light sources like LEDs, T5s and CFLs. It is a soil less mix, meaning that it contains no nutrients, so it will be up to you to supply everything that the plant needs. It has a neutral pH of 7, which is a bit high. Adding 4 grams of 17% aluminum sulfate per gallon of soil mix will lower the pH to an acceptable level. If you're using HPS lights I would recommend Pro Mix BX over the HP. It holds a bit more moisture and works better under the higher heat of HPS lights.