Nutrients or am I wasting potential.

Add some mycorrhizae to your substrate, something like "Mykos" or "Great White Shark". They may be expensive, but are worth every cent! These soil fungi live on the plants' roots and basically "pre-digest" nutrients in the substrate, meaning the nutrients are far more readily available for the plant, with a corresponding efficiency of nutrient uptake and a noticeable increase in plant vigor. Through this increased efficiency, feeding is less frequent and the plants are far more resilient to pests and diseases too. Adding the mycorrhizae is not an instant effect, but will take 2-3 weeks for the fungi to colonize on the roots and then they get going. If added to the substrate pre-planting, as soon as the seedlings emerge, the mycorrhizae start growing on the roots, meaning nutrient uptake efficiency basically starts from day one. They are so good for the plants, that I think their addition to the substrate should be compulsory for every cannabis grower, so convinced am I about their absolute benefit to the plants. Hope this helps, Organoman.