HELP! What are the brown blotches on the 1st & 2nd leaves?

[DeanONH]

I have 2 plants in a 10 gal. tub setup as a top fed DWC. I am using the 600 watt grow article as a model. I am using RO water, CalMagic, HydroGuard, & GH Flora nutes in the recommended dosages. I am using a1200 watt Phlizon LED lamp; 24hrs at 18". PH is 5.8. Both plants are 18 days old from seed. They are just sprouting their 4th nodes. Temperature & humidity are within range. One plant is fine and the other is showing significant brown blotches on its 1st & 2nd node leaves. .

[Tersky]

How do the roots look? are they brown or slimey? It almost looks like ph or root issues, even phosphorous deficiency but with everything you are describing, it sounds good. The light seems a little close to me, but if it was light burn you would have noticed it on the top leaves first, Are they both in the same tote? If so, and it is some kind of root rot or disease then the other plant could be in jeopardy too. Hydroguard usually does good to combat root rot though. I use RO water and have to add calmag, but it looks like you are doing that. I feel as if there may be some kind of contamination somewhere that affected that plant. How often do you change your res?

[DeanONH]

Yes, both plants are in the same tote.

I checked the roots of both plants and they are long, fine, white, and not at all slimy or brown.

I let the res go for the 1st 2 weeks and then changed it. I am due to change the res again in 3 days.

[Tersky]

Huh. Nothing sounds too horrible. I do a res change every week, but two shouldnt be too bad. You test your ph daily? Had any swings? Thats about all the ideas i have. Its bizarre. Looks more like phosphorous deficiency than anything, but having both plants in the same tote and only one having symptoms made me think of a root issue with one of the plants. You checked and the roots are healthy. only other thing i can think of is that it had bad genetics or some minor trauma. Maybe someone else has other ideas.

[YYCannabis]

Are the plants the same strain?

[DeanONH]

Yes, the 2 plants are the same strain, Nirvana Wonder Woman, as in the 600W Grow.

Yes, I check the PH daily. It has ranged from 5.6 to 6.2.

I will be changing the res weekly. I didn't see much point in changing the res after the 1st week since they had just germinated.

Any suggestions as to where I should go from here?

[Tersky]

I would just keep an eye on it. If it gets worse then something is wrong. My hunch is that it will grow out of it. Just check for pests, algae and other unwanted things. It looks to me like the disfigurement is worse on the oldest growth and is less evident on the newer growth. I take this as a sign that it is getting over an issue. If the newer growth was being effected worse than the older growth it would make me think that something was currently wrong with it. I hope that makes sense...this god damn Gorilla Glue #4 im smokin makes it hard to grammar lol

[DeanONH]

It started out on the left leaf of the 1st node about 14 days into the grow. The 2nd node was fully formed. It spread to the right 1st node leaf, and now it is starting on one of the leaves of the 2nd node.

I'll watch it closely and followup here if there are significant changes; good or bad..

Let me know if you have further thoughts.

Thx for the help.

[YYCannabis]

Despite the fact that they are the same strain sharing the same nutes and lights etc... there’s nothing saying that it can’t be a nute deficiency. Looks like phosphorus issue.

Are the leaf stems red in color?

[DeanONH]

I corrected the problem. I was improperly compensating for the mineral deficiency of my RO H20. My tap water has a PH of 7.3 & a TDS of 372. This water leaves leaves heavy mineral deposits. I did not want it in my hydro tank. The RO H2O that I use has a PH of 6.2 & a TDS of 20. As soon as I increased CaliMagic from 2ml / gal to 7.5ml / gal the damage stopped spreading. It took a month for the unseen damage to go full cycle to the appearance of the damage. It was interesting the one of my plants suffered from the mineral deficiency while the other one did not.

[DingusKhan]

Nice job figuring that out, and getting the Cal up. I should go ahead and bump mine to 7.5 as well, I was getting similar blotches.

Unfortunately, once nutrients and a living plant are added to the bucket solution, the water will leave a residue in your bin whether you started with RO or not.