Why does this keep happening? New to rockwool...

Hey everyone, I could really use some help please!

About 9 months ago I switched from coco to rockwool and Ive been having problems ever since.

I am running ebb and flow. 4 inch rockwool cubes. Using only Cyco A&B. PH 5.5-5.8 Growing Jilly Bean. All plants are from the same mother.

I flood once a day in veg with no problems. Temps are 75. Humidity 50%. Tons of air circulation. 4x8 Table under two 1000w MH air cooled hoods. 18 to 24 inches between canopy and hoods. Flooding once a day with Cyco Grow A&B with pH at 5.5-5.8 using the recipe provided by Cyco PLANTS LOOK AMAZING. (see pics - First 2)

When I move them to flower I keep everything just about the same. Temps are 75. Humidity 30-40%. Tons of air circulation. 4x8 Table under two 1000w HPS air cooled hoods. 18 to 24 inches between canopy and hoods. Flooding once a day with Cyco Flower A&B with pH at 5.5-5.8 using the recipe provided by Cyco.

A few days into flower I always notice leaf discoloration. Usually yellowing with spots or sometimes straight to brown and crispy. (see pics - Last 4)

So I have tried everything I can possibly think of to correct this problem. Bear with me. Below will list the ways I tried to correct the problem, in order. I changed one variable for each grow to try to eliminate the problem.

1. My cubes were very wet the previous grow so I payed extra attention to the weight of the cubes during this grow. Making sure they were never too wet/too dry. This did not fix the problem. Same leaf discoloration.

2. I thought it could be nutrient burn so one cycle I began with only water. After 3 days I noticed the same leaf discoloration occurring.

3. I thought that maybe using only water caused a deficiency so I began with a less concentrated recipe. Same leaf discoloration.

So what is happening here? Why is this happening when everything is consistent from veg to flower?


- Some leaves look like nutrient burn and others nutriet deficieny. So I thought it may be pH, but I check/adjust it an hour before flood to be between 5.5 and 5.8?

- I am only using 4 inch rockwool cubes. Do I need to place these on a rockwool slab or something similar for flower?

The problem continues through harvest but its never detrimental. However, I know what these plants can yield in coco, and they are not doing so in rockwool.

Please Help!

Pictures here:
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www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.07.45.jpg
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no pics? Sounds like cal mag issues, I've seen plants not show it during veg and almost instantly show after flip, easy to fix!! I'm not saying it is that w/o pics no one can tell but I stole this from internet, look at all similar?

Not sure why the pictures didnt upload. There's just some icons with an x over it. Heres the link to the pics.
www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.06.01.jpg
www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.05.52.jpg
www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.07.29.jpg
www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.07.45.jpg
www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.06.44.jpg
www.prettylightslive.com//wp-content/uploads/2016/10/2016-10-21%2008.07.09.jpg

I dont know ebb and flow, but will take a few stabs at this.
1. I usually dont switch to flower nutes until after the stretch around day 21 after flip
2. you dont use some sort of rock or clay media to cover the roots when they come out of the cubes?
3. PH off? do you have buffer solution to recalibrate your meter?

looks like a combination of things. the first couple of pics all i saw was white spots that look like early mite damage, the little red spots are cal def., the bigger patches look like mag, i'm not a hydro guy, but the bottle of cal-mag says it has to be over 6.1 to be absorbed. not sure if thats the case in hydro but it could be. the big white diagonal patches look like the damage from ph swings.

Grojak said:

no pics? Sounds like cal mag issues, I've seen plants not show it during veg and almost instantly show after flip, easy to fix!! I'm not saying it is that w/o pics no one can tell but I stole this from internet, look at all similar?

Click to expand...

I had this exact same thing. Cal/mg issue due to ph lockout. Feeds were ph balanced but waterings were at ph of 8. Tap water, no meter,my bad.

Thanks for all the fast replies!

Is that common practice to not switch over to flower nutes that late in?

The roots haven't expanded beyond the cube. I was under the impression that they could still support a large healthy plant in that cube so long as the feeding schedules kept up with demand. However, I don't know if I entirely believe this which is why I was contemplating adding a rockwool slab underneath.

I calibrated my ph meter a couple months ago but I'll do it again to be sure. Need more calibration solution.

Those white spots are reflections from neem. Unless you're referring to the white spots in the first reply. That's not my pic.

I could definitely see Cal mag being the issue. My nutes have that, but I've read they don't have enough. Do plants in flower require more cal-mag? I don't have these problems in veg.

I ph regularly so there hasn't been any swing. Maybe my meter is off.

let your ph swing up to 6.2 and add 2 or 3 ml of cal mag, do that for two feedings, and in the future, swing between 5.5 and 6.2 and i bet it at least improves if it doesn't totally go away

yeah most people wait till after the stretch to switch, the plant is still adding tons of new growth and needs the N to get that done.

i calibrate my meter at least once a month. i think ebb and flow doesnt have a fast ph rise like DWC correct? so i dont think you should start at 5.5, maybe more like 5.7-6.2 range.

Also what are you using for ph up and down . I had a problem like yours, and changed my down to a sulfuric acid solution, and bubbled it for 24 hours with my calmag then add the micros , bubbling 24 more, then add what ever else keep bubbling then Ph bubble some more check Ph if it's all good use it.

Youre most likely root bound in a 4" cube into flower. Throw them in a pot of hydroton and take off the liner for the cube! Let them roots stretch!!

blueberrysmoke said:

Thanks for all the fast replies!

Is that common practice to not switch over to flower nutes that late in?

The roots haven't expanded beyond the cube. I was under the impression that they could still support a large healthy plant in that cube so long as the feeding schedules kept up with demand. However, I don't know if I entirely believe this which is why I was contemplating adding a rockwool slab underneath.

I calibrated my ph meter a couple months ago but I'll do it again to be sure. Need more calibration solution.

Those white spots are reflections from neem. Unless you're referring to the white spots in the first reply. That's not my pic.

I could definitely see Cal mag being the issue. My nutes have that, but I've read they don't have enough. Do plants in flower require more cal-mag? I don't have these problems in veg.

I ph regularly so there hasn't been any swing. Maybe my meter is off.

Click to expand...

I switch when they start to flower usually about 14 days in however I have a quick finisher that gets it after 10 days and I've seen sativa's take 3-4 week of veg fert. If I did 21 days on a 55 day plant that just doesn't make sense.

Airwalker16 said:

Youre most likely root bound in a 4" cube into flower. Throw them in a pot of hydroton and take off the liner for the cube! Let them roots stretch!!

Click to expand...

wow i just noticed that, the liners are still on the cubes. 4 inch cube are ridiculously small, listen to Air^

Root bound. put all your blocks onto a slab or bigger blocks or fill the tray with grodan cubes or even hydro clay right before you flip and you will be golden.

Salt build up/cal mag issues? Do u ever rinse with straight water or a low ppm nute solution to remove salt build up?

no offense to anyone saying rootbound, but i had friends in CO doings 2+ lbs out of two stacked 6x6 hugo blocks. these plants were massive. i am running the same setup as you but i have a coco mat under my plants. i would agree with the pH lockout statement above more than anything as i have had the same thing happen. I am also flooding four times during lights on for three minutes each time. small amounts of media must be fed often. thats the benefit of doing small cubes. you feed kind of like a weight lifters food regimen. meals every two hours.

next time spend 35$ and get yourself a coco mat. this is my first run with them but the plants LOVE it and they root all underneath it and soak of the little puddles in the bottom of the tray.
keep track of your pH and you should be fine. my little seedlings got the same thing going. i got lazy for a week and they paid the price. rock wool and coco are both nice. i am running both right now. for SOG you cant beat RW. for big monsters i like coco and want to try out SIPs.

remember that those leaves wont ever look normal again. once i think i have fixed the problem i like to remove the affected leaves so that i can see if its progressing or not. its easier to keep track of new damage that way.

oh and drip clean is your best friend. its cheap enough, the dilution rates are really high. it'll last forever.