Week 4ish, new growth yellowing

[Kweku Ananse]

Co2 issue? 1000 ppm co2. Isnt 800 the optimum?

depending on ppm of feed...

but this just jogged my memory, i believe this COULD be a reaction to co2 levels being out of balance, causes yellowing. but i didnt think it was in the new growth. i cant remember but im fairly certain that there is a lot of talk on this forum on optimum co2 levels / debate.

i do know iv read that too much co2 causes some chemical/hormone that doenst normally get produced much to express some yellowing... or maybe it just chokes photosynthesis? i cant remember what i read lol

advice, for us both, search and read EVERYTHING you can find on co2 levels... it was like a days worth of reading until i decided on my numbers for co2 ppm

400veg
600wk1
750wk2
900wk3
1000wk4
1100wk5
1000wk6
800wk7
600wk8
400wk9+

but thats just my strain in my system with my nute schedule

so you gotta find what works... but its possible your co2 could be too high.

as if that helps at all lol

 

[Zarezhu]

I've done a fair bit of research into co2 levels. I set my chhc4 to 900ppm co2 with fuzzy logic, and a 100 ppm buffer. This keeps my co2 levels at 900-1000. seems to be the magic number. 1500 has been debunked, and 1200 is shown to have no benefit opposed to 1000, so I've been hovering there.

So last night, they seemed to get worse. Got the co2 tank hooked back up, and I watered the plants with .5ml (opposed to my typical 4-5mil) calmag, and equal parts A + B + Cannazyme, +drip clean, at a ph of 5.8 and EC of .8 in 63 degree water. Only about 3L per plant. I had to throw a splash of silica in last because the ph without the calmag was dipping to like 5.4 or 5.5, which really sucks because silica needs to always be added first. I also found out cannazyme can staay in a res up to 10 days, so I'll be using i every watering now, along with pk13/14 for at least 5-7 days.

Runoff was 6.0 ph, but the EC did seem to be 1.6 to 1.8, higher than usual. I want my runoff EC back down to 1.3ish, so tonight, I will water at least 5 or 6 L per pot with something around .4 EC.

If tonights flush puts the runoff at proper levels, tomorrow I will start to feed again with little to no calmag, A + B, cannazyme and pk 13/14 (plus drip clean of course), at an EC of 1.3. Should I perhaps up the EC to 1.5-1.7ish?This would be after 2 days of light/moderate flushing. Could I just flush them tonight and then immediately after water again with my 1.5EC new solution? I'm gonna flush em with as much water as my RO machinee was able to purify since last night, could possibly be 2 gallons a plant.

@zarth- the yellowing isn't from hotspots or light being too close, its pretty even throughout the tray, from corner to corner.


A new theory! I'm only watering 1x a day. PERHAPS, the pot dries out slightly more than it should? Perhaps I really need a 2x daily watering at minimum , to keep ph/nute levels from swinging in the media? It's still fairlyy moist when I go to water every day, but not nearly as wet as when it first gets the feed. The little root hairs corresponding with the new growth could be seeing too much of a shift in media ph/EC/moisture, much like if the pot goes completely dry. I NEED TO HOOK UP MY IRRIGATION ASAP. Can probably start a 3-5x multifeed TOMORROWS watering, as tonights res will be depleted during the flush

 

[Kweku Ananse]

Yes your new theory would produce the same symptoms. I've seen it happen in coco before.

Imo, waste nutes, runoff more / water more frequently --- instead of not enough.

Aerate your nutes with an airstone or two for about 4hrs, then pH and feed oxygenated ferts, no worry about overwater in this scenario.

Forgot you've got a couple day res, not topfeeding like I do, one res per water, rinse, mix, repeat

 

[Zarezhu]

I completely agree with the waste nutes and runoff more, waaaay better to be on the safe side. I almost always runoff at least 15-20%, and use DripClean every watering. This is just until I've got coco dialed in 100%. I'll eventually switch to no runoff, as it seems all the pros do it that way. This is only my second try at coco, should be dialed in another cycle or so.

My res is 100 gallons, I used it last cycle with my irrigation setup, but this cycle I just filled my res with RO water, and pumped into a smaller 20g tote, were I did all my nute additions and phing daily. Except for this last week, were I mixed the whole 100g with .3EC calmag and enough A+B to hit 1.3 EC. Been using that, I dumped the last of it yesterday because I needed to start fresh with no cal-mag. Got the res filling up right now (takes almost 26-27 hours to fill it to 100 gallons, motherfucking RO lol). Ima use all the water I have tonight, prolly 60g worth, on the 24 plants with a heavy flush.

Thinkin I'll foliar ONE TABLE tonight with META-K, a potassium supplement. If the cal/mag is causing potassium to lockout, OR if I have been underfeeding potassium, which could be my symptoms, the K foliar should prove to be effective by the followng day. The rest of the tables I'll foliar with a humic supplement.