Most indoor gardeners are interested in two things - the quality and quantity of their fruit, flowers and blooms. Most nutrients have a bloom formulation which contains all the elements your plant requires for the bloom phase, but for truly superior results, a dedicated flowering additive or booster will have a massive impact upon your overall crop performance. The most common type of flowering additive is a PK booster such as PK13/14 or Vita Link Buddy amongst others. These additives are very high in potassium and phosphorous, two elements that are essential for fruit and flower development. There are many products that add these elements into your feeding regime and they vary in strength, formulation and application. We recommend you experiment as much as you can with the various types to see what works best for your plants. The other major "type" of additive used during the fruiting/flowering phase is a bloom stimulator such as BOOST Accelerator or House & Garden Bud-XL. These types of products stimulate your plants flowering response and have many benefits that lead to increased yields. They need to be used in conjunction with PK type products as they create demand within your plant for these flowering elements. In summary, flowering additives are one area of nutrient formulation that sees the most innovation and development as it has the most directly effect of plant performance. We highly recommend that you experiment regularly with the many products in this field as getting this element of your feeding regime will have a massive positive impact upon your grow room performance.