PPM out consistently higher than PPM in

About 4 weeks into flower on my first grow. Indoor auto in FFO soil. I’ve been giving FF trio and cal mag for about 3 weeks or less now. Plant looks superb and has throughout the grow. I flushed once just over 4 weeks ago when I thought I added too much lime. PPM has been about 200 more in runoff than what I put in. Ranged from 1100 in to 1300 put. Tonight was 1500 in and over 1800 out. I’ve watered 5 times till run off since sept 2. No fert in watering last time ( about 4 days ago). Plant looks great. Should I be concerned? Dial back fert for next few waterings?

FFOF ppm runoff with just water going through should be between 2000-3000. Sounds like you’ve flushed all the nutrients out of your soil. Going to take more work keeping them healthy.


Use distilled water and check ppm output. Knowing what the soil is still holding onto is crucial for being able to know what to put in.

That being said push that plant until you burn the tip of the leaves back and hold that ppm until your ready to flush out and harvest


They seem healthy now. I’ll keep an eye on them. Never had PPM that high come out since I started checking a month or so ago.


I don’t grow in soil. But you should shoot for about a 200 + difference in or out in coco. I would think it would be about the same for soil. After that. I start looking for why I am starting to drift. I learned in my first grow. Don’t chase numbers. If your plant is doing good. Watch the numbers. But don’t try making big changes. Over time. Things seem to balance out. Just my O2 :grin: @Covertgrower, @Missiles, @Myfriendis410, @MattyBear would know better than my self.


So I see folks saying they feed with each watering, and others say you have to straight water(no nutes) between feedings to understand what the plant is consuming. With the auto flower life cycle being short, I consider the missed feeding the plant will have by going straight water. Also, if ppm read out is low in the runoff of just straight water, it’s several days before I’m able to feed due to not wanting to overwater

If it’s low on your runoff, low enough to not sustain until another feed, just go back in with a feed.


Love the Wu

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At the same time, if everything is looking good, is there something to be said about just keep doing what I’m doing? As to @Not2SureYet point, don’t chase numbers. Or, best to do a distilled water watering just to see where I’m at? Seems no significant risk to do a no fert water if I can immediately follow with a fert water if ppms are low. I guess I’m just talking out loud at this point.