Originally Posted by ilovesluts420
I’m running the Gavita 1700e’s. I had some problems early on in the veg stage with purple stems but now it’s coming back during week 3 flower. Are the lights too strong? They’re at 70% right now. I am slowly bumping up the brightness by 5% a week. Maybe I need more cal mag or nitrogen? Or both?
I think you're probably on the right track. A lot of LED users are finding these type of results, and I have a feeling it's something we'll all have to dial to our specific conditions, until someone figures out a formula for how much nutrients plants need in which stage of life, and at what light intensity.
If you're slowly bumping up light intensity, but keeping the same feed level, that might explain the eventual deficiencies you're seeing.
For efficiency sake, you could try turning the light back down slightly, and see if they grow at a better rate, with more even greening. Or you could bump the feed up with the lights, and see if they green up, and grow faster.
I'm going through this fine tuning myself, and wondering how a lower light intensity and feed level will compare to higher levels of both.
I just use Megacrop, pH down, and pool shock, to see how simple I can get away with.
I used to feed the MC at 4 grams per gallon, but I was still getting purple striping and leaf stems here and there, and other signs of deficiency, so I bumped the feed to 5g/gal, and they started looking better.
Well, I bumped the lights up, and eventually they started looking like they were lacking again.
Now the lights are back down, and I'm watching to see how they react.
I've been stubborn, and trying not to add Epsom, but I finally did in a spray bottle, just to try spot spraying a couple particular hungry looking plants. I've only done it recently though, and don't have results for you yet, sorry.
If I don't get satisfactory coloring or smells in the final buds though, I'll probably start adding it to the rez.
Anyway, you could try adding a little of any or all of the suggested nutrients, or you could try turning the light down a little, and see how they react.
Oh, right, you're in the 3rd week of flower... You might not want to bump the food up too high, for too long if you do. They won't want as much of it in a few weeks.