Help With First Grow - Discolored Leaves

[Laredo7mm]

Hydro Growers:
1. Are you growing from seed or clones?
From seed
2. How old are your plants?
Almost 2 months old. The sprout broke ground on November 25th.
3. How tall are your plants?
About 29”
4. What type of hydro system are you using?
DWC
5. What brand/type of nutrients are you using?
GH flora trio
6. What is the Ph of your nutrient solution?
Currently at 5.8
7. What is the PPM/EC of your tap water?
Using RO water at zero PPM
8. What is the PPM/EC of your nutrient solution?
About 1050
9. What is the temperature of your nutrient solution?
About 69.1F
10. Does your PPM/EC show a rise or fall when you do your daily PPM check?
Just did a res change yesterday so it rose a bit from 950 to 1050. Before the res change it was dropping.
11. Does your pH show a rise or fall when you do your daily check?
Lately it has been falling. Had a large drop the other day before the res change. Dropped from 5.7 to 4.9 over night and ppm dropped from 1002 to 703.
12. Do you foliar feed or spray your plants with anything?
No
13. What kind of lights do you use and how many watts combined? (HPS, MH, fluorescent, halogen, incandescent "plant lights")
HLG QB304 quantum at 3700K
14. How close are your lights to the plants?
About 14 inches and set to 55K lux
15. What size is your grow space in square feet?
3x3x6 so 9 square feet
16. What is the temperature and humidity in your grow space?
Temp is at 77F. RH at 50%
17. Have you noticed any insect activity in your grow space?
No
18. How much experience do you have growing?
None. This is my first grow.

Hey all, new here and this is my first grow. I have been fighting a battle with discoloring leaves for about 5 weeks. The first spot was a rust looking spot on one of the large fan leaves that showed up around December 12th. I have tried everything I can think of from lowering nutrient strength, lowering the light output, increasing Rh, lowering Rh, etc. but nothing has helped.

There are some newer looking leaves that don’t look bad, but the majority of then start by showing little tine black/brown spots on the new leaves and then it spreads to what is shown in the attached pics.

I did have an initial PH issue very early when the plant only has one set of real leaves. I didn’t know that my ph would change after bubbling the water, so I had some hig ph for a bit that I fixed right away. After that, until about a week and a half ago, I was keeping the ph at about 6. I just had the GH ph indicator drops to test with so I don’t have an exact value. I picked up a ph meter and I am now trying to start it at 5.5 and top off with RO water and let the ph rise naturally, but recently, I am having ph drops every morning when I check the res so I am adding some ph up so it doesn’t drop too low.

My res temps are ok at 69.1F and I have been using Hydroguard from the start. The roots look a bit brown but don’t feel slimy or stink at all. Looks similar to pictures I have seen and people said it was staining from the nutrients. I have recent also been adding 20ml of GH flora blend to the 5 gallons of nutrient water.

I have my 7 gallon bucket (holds almost 5 gallons of water and doesn’t touch the bottom of the 6” net pot) in a cardboard box. The cardboard box is attached to my external humidifier and acts as my air intake. I think that is helping the res temp stay lower since the evaporative cooling of the mist and fresh intake air first flow by the bucket before mixing into the grow tent.

I have also been using cal mag since the start. Right now I am using 20ml in 5 gallons of water. Before reducing it a bit, I was using the full 5ml per gallon.

Tomorrow willl be the start of week 5 of flowering. The strain is Nortern lights special from KC Brains Seeds. It is a photoperiod plant getting a lighting schedule of 12/12.

I probably shouldn’t have put it into flowering until I had this issue figured out, but my tent is vertically challenged so I flipped the switch when it was about 13” tall. I haven’t done any training, just some light pruning to remove some of the ugliest almost dead leaves.

Any help will be greatly appreciated.

 

[Homesteader]

Looks like you have at least a few issues going on. For one, ensure that you don't have any mites because they tend to cause a mottled leaf from the damage like yours look. Aside from that though. Calcium and magnesium are visible deficiencies to me. With calcium def, it will always cause brown/rust spots on fan leaves as it pulls it away to feed the flowers and with magnesium, it will drain the color from the interior of the leaf and the veins of it will remain dark green. Cannabis consumes calcium like nothing else (except carbon) This is fairly normal if you don't have enough available in your mix or nutrients. Sometimes though, if you are giving it too much of one nutrient, it can lock out another, so dumping cal or mag on it isn't always the solution. Check mites first. Im a soil grower by the way but I'm just going by looks.

 

[Nugg]

Yep...if you are running ro water to must run a cal mag of some sort...I'm run undercurrent dwc.

 

[Laredo7mm]

Thanks for the replies. A calcium deficiency was my first thought. I have been run calmag from the very start. I did raise my ph a few weeks ago to 6.2 and that didn’t seem to help.

Here is my current nutrient schedule for 5 gallons:
20ml CalMag
20ml florablend
60ml flora bloom
40ml flora micro
10ml flora grow

Should I bump the ph up to 6.2 and add another 20ml of calmag?

 

[Nugg]

I just hold a 6.0-6.5 through out the grow..Cali-magic I believe it might be called..I run my well water.i don't measure anything anymore so I couldn't tell you how much..

 

[Laredo7mm]

Right on. I went ahead and added another 20ml of calmag. Mine is actually called calimagic from GH. I also bumped the ph to 6.1. We’ll see what happens. I was running the 6 ph range for quite a while with the same symptoms, but maybe she is just hungry for more. I was running 5ml per gallon up until a few res changes ago, so now I’m at 8ml per gallon.

I did look at the underside of some of the leaves that have the damage. I didn’t see any bugs or any evidence of them. Looked with my 30x loop.

 

[Monster762]

I just hold a 6.0-6.5 through out the grow..Cali-magic I believe it might be called..I run my well water.i don't measure anything anymore so I couldn't tell you how much..

Yup calimagic is good calmag. I’ll per l but in flower I bump it up. Ive never run hydro but directions are the same. 1 ml per l. But I use 6 ml per gallon after about a month in soil cause the plant eats it up. I would bump the calmag a bit.

 

[Laredo7mm]

Hi all, I just wanted to stop by give an over due update. I was never really able to figure out or stop the issue, but I didn’t really have much time since I was already in flower. She flowered nice and I ended up with 4.6 ounces of dried product from her. I may have chopped a bit too early, but the quality of my homegrown is better than what I used to buy, but then again I am not any kind of connoisseur.

I’ll have to wait a bit for my next grow as I have some work related travel coming up for the next few months. Not sure if I want to grow in the summer months as it will be difficult to control the temperature and humidity so it looks like fall will be my next opportunity.

Thanks again for all your help.