Wow...and I am seeing completely different results?
Yeah, fuck if I know. Lol. After thinking about this a little more, I went and looked back at my grow log, I actually hit 1600ppm about 5-6 wks in with one of the sisters of the other strain I am also growing, and it liked it.
I also never changed that tub the whole grow, including even before I switched to 12/12! And it turned out pretty good, except for a little burn from the 600w halide being too close.
But the O.P's question was about dehydration, I guess you haven't seen the effect of this, but I sure have. Dropping the tds has had very pronounced effects on the buds drooping down how I like instead of going straight up into my lights.
But I'm not saying that I always see that, because the clones of that plant I hit 1600ppm with are currently at about 1050ppm, about 6 weeks in or so, and they are all still standing straight up, other than the stems I deliberately crimped and bent down. But annoyingly, the leaves are also not all nice and green, some of them are pretty light, and the buds are not as big, the plants are not as developed. (And I Still have tip and edge burn, wtf!) But I did drop the wattage down too, and didn't veg in the tubs at all with this one either. So I'm not making too many comparisons with this one.
I'll need a couple more grows with this strain to dial it in nicely. I alway fuck around with too many variables at once for my stoned ass to be able to decipher everything right away. I'm also trying to figure out my new optimal co2 level with my new lower wattage, I dropped all my flowering lights to 400w from 600, hopefully doesn't kill my yield. Just sick of light burning the tops and sick of my ac running for 12 hours straight, pulling 1400w the whole time. (If the 400w thing doesn't work, all I have to do is screw my old 600 bulbs back in and turn the dial on the lumateks back to 600.)
Another thing I've noticed about tds, in my veg dwc tubs, I'll see a progressive increase in tds requirement, until I have to change the nutes. In other words, say the nutes are a month old and are at 900ppm, when I swap it out to an initial 700, the leaves will usually actually darken. So that's just one more out of a million other variables, how often you change the nutes.
I haven't done enough experimentation on spiking the tds up and starting the flush early vs creeping it up and starting it the normal amount of time, so I don't know much about that yet. But I normally cannot flush for 2 weeks, I know that, or the plants will die before the end of the flush. Last time I had 1 plant die after 10 days, the other 2 in the tub with it were almost dead too. So maybe my tds wasn't high enough. I don't know. But what can you do if you're already getting tip and edge burn, ram's horns etc with evenly green leaves? I never really liked the idea of spiking the tds up just to start the flush early, with aero I hardly even had to flush at all, maybe 3 or 4 days, no joke. But with only 360ppm, if I ever got thirsty in the grow room, I could drink a glass of water right out of the res! I never did, but I'm sure you see my point.