What is the ideal range in ppm for chloride?
I won't pretend to have that number and I agree with the following statement from the previously linked article.
If someone were inclined to jump down that rabbit hole with some in depth experimentation, they could potentially use the information gleaned to develop a lucrative "terpene boost" nutrient additive. Of course it would require a lot of plants to have multiple feed groups of plants including controls, and one couldn't do such an experiment without including the strain variable too. I assume one would mainly be working with potassium chloride, magnesium chloride, calcium chloride, maybe ammonium chloride. Can the same results be achieved with one of the aforementioned compounds or do we get improved results with some combination? The development of the perfect terpene booster would also need to quantify how chlorine collects in various medium types. One may find that with say perlite, the chlorine builds up fast where it doesn't accumulate in other mediums. That's just an example, I have no reason to believe perlite would do that but one would need to include multiple types of growing medium and no medium with DWC. So it would entail a great deal of experimentation requiring a very large number of plant groups. The more plant groups we can run at one time the faster information can be gathered. I agree that university experimentation would rapidly accelerate the process. If I had to
guess, I would wager the magic chlorine number is small and that you just need some chlorine available, and that it's probably really easy to go overboard, perhaps somewhere between 5 and 25 mg/l ?
I wonder if there are any studies on the chlorine/terpene relationship involving other types of flowers or other terpene producing plants. Some digging there may prove fruitful.
As to what I have done with KCl, I have only used it during ripening so I don't know what the effects would be if it was used earlier in flower. I would be worried about accumulation in my peat based mix. If I were to mess with KCl earlier in flower it would be very small amounts and likely not every feed.