Botanicare Pure Blend Pro Grow, Nutrient, 3-2-4, 5 gal.

I am using this for Kratky hydroponics. I am new to this so this is the first time of using the product. I found it difficult to know whether the instructions were giving quantities for watering plants in soil or otherwise. I used a PPM meter and found that l had to use quite a bit to get to 1000ppm which is what l wanted for 5 week old lettuce and herbs. i was using a 5 litre container. I have only used it for one plant as l am worried it may keel over and die!