That’s a great point too. Big differences in light and ventilation between indoor and outdoor.
Day 16 of Flower
Starting to get some frost! Very excited and everything is moving forward nicely. Ever so slight tip burn is telling me they’re getting as much nutes as they can take and they seem very happy about it!
Tnelz Sour Diesel:
Star Pupil:
Sunset Sherbert:
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Just past the 30 Day mark in flower. Almost halfway there! Seeing a little burn on the edges of all the plants. I might have hit the ppm a little high, so I’m dialing it back down to about 1300.
The TNelz Sour Diesel in the back are rocking full strength. It seems the Star Pupil (Front-left and Front-center) are lagging, but I’m told it’s a 77-Day flower on those, so to be expected.Sunset Sherbert (Front-right) seem to be keeping up with the Sour D
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Day 47F
Buds are starting to weigh down and lean over. Thinking I have to get a support net ASAP. Also have a loupe on order because it seems like we might be getting into the last few weeks? Not sure. Just came back from a week on the road to find some yellowing of some leaves. I’m concerned there may have been an issue with their feedings for a day or two. Hopefully they’ll bounce back and show me signs of happiness again.
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have you flushed at all this run? when i first moved to coco in flood and drain i kept getting issues like what your plants are experiencing about 2/3 of the way through flower. coco seems to hold onto salts like crazy. i now flush at least 3-4 times/run to just reset the coco and avoid buildup/lockout. guy over on ic who grows the exact same way as me said he flushes them with pH’d RO every week and never experiences any buildup issues at all.
i could be wrong about your problem, but that was the cause of a similar issue for me. plants look good still and i wish you a good harvest!
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I haven’t flushed at all! Did you top feed with RO water or just put straight RO in your rez? I have been using SLF-100, which was supposed to take care of this, but maybe it’s not.
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Looking great @bisceg. How far are you keeping your Rack from your canopy? Getting that distance right is a big part of the dial-in process that will maximize DLI without leaf bronzing or bleaching.
You will likely find your plants don’t need as strong a nute mix under LEDs. I generally recommend dropping nute levels by 25-33% until other metrics are established when moving to LED from HID.
Otherwise great looking garden, eager to see how it finishes. Peace -b420
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if you’re top feeding to a decent amount of runoff and ensuring the coco is always wet then you are likely fine, especially using slf-100
was my first thought but seems i might have been incorrect in light of info i failed to find earlier in the thread!
I’m doing flood and drain, but wondering how I should flush. It it better to pour RO over the top until the runoff is normal? I just put a few gallons of RO over the top of them and it ran back into the Rez. I measured the Rez runoff ppm at about 4000! Could they be holding on to that much? I always kept the Rez at about 1300 and it never rose after flooding. The floods never get above 5” from the bottom. Now that I’m pouring RO over the top, is there a bunch of built-up nutes that are getting flushed out above the flood line? Holy crap, I thought I was on cruise control but now I’m nervous! Thanks for all your help OG!
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The rack is a good 8 inches above the tallest plants. They never had a problem with it, so I don’t think that’s it. I’m really worried about the build-up as @GooseGrows suggested
i generally flush on res change day. pump the old water out and then flush the plants one at a time and let it drain into the reservoir. once all of them are flushed i pump and dump again and then clean everything and mix new nutrients into fresh water. you could of course do it all in a sink or bathtub, i just don’t have the option where i grow.
i wouldn’t suggest flushing into the reservoir you’re flooding your plants from unless you’re going to change it out right after. you’ve seen the ec/ppm of the runoff you’re getting, so you probably don’t want that going into your reservoir.
you’re not fucked. my suggestion is to do a really good flush and get them into some freshly mixed nutrients. also, idk what nutrients you’re using, but in flood and drain i have found that less is more. i don’t get over ~650-700ppm at any point. 4000 is crazy high runoff, haha!
so far in a couple of years growing in coco flood and drain, coco’s tendency to hold onto salts when bottom-fed seems to be the only real challenge. since i started flushing a handful of times each run, that problem has gone away and i’m not seeing lockout. i have also had plants herm from it as well.
i am no grand master, as i said i’ve only grown in flood and drain for a few years now, but i hope the info helps 
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Definitely helps-immensely! I didn’t really have this on my first-grow radar, especially thinking the SLF-100 had me covered. I’ll do all this tomorrow and cross my fingers.
One last question (for now) how much do you flush one plant with? Ballpark? As you know the RO can be a slow supply and I have six 3gallon fabric pots. Thanks again!
i generally run 5 gallons through my 3 gallon pots, but it sounds like you have some serious buildup going on, so i would prolly just test the runoff periodically and flush until it’s almost back to 0ppm.
Awesome. I’m gonna be flushing all day (RO is slow) and letting them dry during lights off and go to a 700-ish ppm until harvest. Thanks for your help on this @GooseGrows. You may have saved my run!
OK, so I flushed by pouring RO water over the top of each of the pots. It took a lot of time to generate enough RO to do this, but my runoff eventually got down to under 200. I couldn’t do it any more and it was quite an improvement from over 4000 ppm measured from the runoff of the first flush!
So now I’m looking at how/why this happened. It seems evident to me that using flood-and-drain doesn’t allow for accurate runoff measurements as I never saw the ppm in the rez go up from where it was originally after a rez change. It always went down which I interpreted to be the plants consuming the nutrients. The only way to get an accurate ppm from the runoff was to flush fresh water over the top of the coco and then measure. It’s almost like all the accumulated ppm were above the flood line and never came back into the rez. Am I way off here in what I saw?
Looks like the plants liked it. They are actually standing up more after less than a day. I thought the buds were getting too heavy, but I think the stalks were getting weaker being locked-out. I did see a purpling of the stalks prior to this episode that I already see clearing up. My imagination?
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In addition to what ever nutes the plants remove from the nute water, there will be losses in the coco, or what ever medium you are using.
What happens is that nute water wicks up above the hi water line through the medium. If the plants dont drink every drop, that water evaporates. Same thing happens when ever the water drains out. The medium is wet, but evaporation begins immediately.
When water evaporates, it leaves all the dissolved material, including all the nutes the plant didnt eat, behind as deposits that build up in/on the medium. This is much the same as what happens in your coffee maker or when you boil a pot dry. Its just slower, and not visible. Doesnt matter if you grow in hydroton, coco, perlite, etc. It all does it.
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Totally makes sense now. I’ll be flushing regularly on all future runs for sure. So glad I asked the OG crew!
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And how often? Not sure if its mentioned…
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How often to flush? Im not sure how to judge that. Im sure it will depend on the relative humidity and temp in the space, how often you flood, and how long the drain cycle is, how strong the nutes, the type of medium, etc etc.
Id let the plants give you hints and test the run off regularly.
Right, I should have said “I’ll be testing runoff regularly”. Then I can tell if it needs a flush. The flushing was a major pain because of the time it takes to get enough RO water to flush all the pots, so I definitely don’t want to do it more than absolutely needed.
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