Having a single answer to this question is about as useful as the crazy, convoluted “feeding charts” most companies want you to follow. IF we all had identical strains, in identical media, in identical rooms, with identical water, then I would just print the only number you would need right on the bags. Unfortunately(or maybe fortunately) we all have different situations that we grow in.
The good news is that no matter the media you are growing in, HGV nutrients will work exceptionally well providing you understand how to use them properly with your conditions.
The two most common medias I see in commercial grows are Rock Wool and Coco(coir) so I will address those two first.
With Rock Wool, having the ability to precisely control your irrigation timings and duration are very important. The more precise your control, the harder you can drive the plants. I personally run both medias and I feed them at the same EC. The only difference is how long and how frequently each media is irrigated. Root zone EC is controlled by those two things and the feed EC is always constant from the injector system I use. The same thing can be achieved with a reservoir. The beauty of HGV nutrients is that they are designed to be fed at one strength from start to finish so you don’t have to change EC or mix in additives at any time. There are three parts. The Base Formula is used for both veg and flowering at the exact same strength. The growth formula will be used with the base formula during the vegetative phase of plant growth. The flowering formula will be used with the base formula starting on the first day of the flowering phase.
I have achieved the best results in both Rock Wool and Coco dripping at an EC of 3.0 and pH of 5.5-5.7 It is very important to monitor root zone EC and pH and adjust your irrigation frequency and duration to keep the media at the correct feed, pH, and water content.
The best way to find out how much base and growth formula or base and flower formula you will need to reach YOUR desired EC level is to start with 1 gallon of the water you use to irrigate with. Everyone’s water is different and will require slightly different amounts to reach the same EC. The following chart will give you a good starting point where you can easily adjust from if necessary. Add the base formula and fully dissolve then add either the Growth or Flowering formula and mix well. The numbers below were taken using Reverse Osmosis(RO) water with a starting ec of less than 0.1. Your actual numbers might be slightly different based on your water supply. The important thing to note here when making adjustments is that the ratio between the Base formula and either the Growth or Flowering formula will always be 0.6:1 It should be fairly simple to reach any desired EC level following the recommendations below. Once you know how much of each formula it takes to hit your target EC, simply multiply the grams of each times the gallons you need to fill your reservoir. The same principal works for filling concentrate tanks. For example, if you have a 50 gallon concentrate tank with an injector ratio of 200:1 you would add the amount of grams needed for 10,000 gallons of water(50 x 200 = 10,000) DO NOT MIX THE BASE FORMULA IN THE SAME CONCENTRATE TANK AS EITHER THE GROWTH OR FLOWERING FORMULA. IN CONCENTRATED FORM, THEY MUST BE KEPT SEPARATE. Please don’t hesitate to email or call if you need clarification on any of this information.
For other growing media, it is up to the grower to determine the correct EC for the particular crop and environment. Soil will usually require a lower EC while soilless mixes, DWC, NFT, and other hydroponic applications can run at the higher levels on this chart. If you are unsure as to what EC you should be running, please email or call us to discuss your particular situation.