Stonerdanswered grow question 4 years ago Well it depends on the parameters you currently have!
knowing just the PPM and pH values won't help you determine what the issue is because it does not tell you exactly how much of each nutrient there is just the general conductivity!
Lets start with directing me and everyone else to the correct plant diary you're having issues with so there'll be more info about your setup.
Once we know that check the tap water PPM/TDS (normally around 200-400) so we'll know the salinity of it (which will also indicate if that's the problem) and if it's useable as irrigation water.
Then once we have all that info we can determine the issue and how to fix it!
To address your fertility regulation question, yes!! with proper diet and irrigation you'll have complete control over your growing medium's fertility!
First you'll need to fertilize consistently and according to the plant needs (I'll address that in a bit), balance the solution's pH to the desired 6.0-6.5 range (5.0-5.5 for hydroponics) and to irrigate with at least 20-30% of the irrigation amount as runoff. This will leach out accumulated salts from the growing medium and replace them with those you put in! Ideally you want the same parameters coming out as in.
As for the proper diet for your plant there's no right answer because every plant is a little different! each strain and each plant of that strain (not a clone) will require different conditions and diets.
To find the right one for your plant you would need to start with lower than recommended dosage of fertilizer (from the fertilizer label), usually about 20-70% weaker depending on the plant's maturity and growth (bigger plants require more fertilization), and slowly increasing it as the plant matures unless a toxicity/deficiency appears and then you adjust the diet according to that issue!.