PPM

either calculated ppm from labels or EC is the measurement to use, otherwise youmay be talking apples and others may reply in oranges. one ec scale is x1000.. so 0.7EC amd 700EC are same thing. ppm-ec conversion has 3 different conversion factors? you can see how that can lead to miscommunication. 1.3-1.5 Ec of a well balanced feed. if you calculate ppm from % on guaranteed lables, it should be 650-750 range. Ratio of nutes is equally important to overall concentration. 120-130 N 50+ P 180-190+ K 100+ ca 50+ mg less than 110 S that's probably on low side, but easier to add than take away. If you have a reptuable hydro nutrient product, it should be ph-buffered. You should not have to deal with swings or balancing anything with a reputable product made by a company that doesn't have their head up their asses. 6 is a better target. things become unavailable below 5.8, and whehther solid substrate or hydro that doesn't change the chemistry inside the plant after it's been drunk by the plant. 6 gives room for error above and below, but again a professionally made hydro nutrient should be ph-buffered and you should not have to balance it. there is a difference between "buffered" and "balanced". You can add any acid or base to re-balance pH. A buffereing agent makes for a more consistent pH and should avoid swings with normal practices for dwc (ie res changes etc / cleaning ).

Usually around a 300 to 400 will do. Ph of 5.8 so you have room for swings.

Hi! I known my answer is going a bit off-topic, but I always advise new grower to start with soil. It's more stable and you can make more recoverable mistakes. But for your actual question, you should check the website of the fertilizers you use.