It yields results comparable to far more expensive brews. Some are nasty. Unmixed PMDD constituents are stable enough. The chelated trace mix should be kept dark, dry and not unduly hot. Some have noticed mixed PMDD will degrade over time and even develop mold.
Light can destablize chelates.
Since dry ingredients are more stable, only mix up a few month's worth of PMDD at a time. Never tried it myself. Too much is not the best thing for your fishes' well being. Too much of specific nutrients can be injurious to specific plant species. Way too much and the excess can actually inhibit a plant's ability to properly utilize nutrients present.