Blotchy leaves - diagnosis?

Hi,
First time grower here! I’m growing 3 w.w. plants hydroponically and I’ve started noticing some blotches on the leaves of my best plant. I’m not quite sure where the problem is, so I came to you guys for help!

Here are the deets of my set up:
-1.5 gallon hydroponics grow cabinet (from dealzer) with LED lights and exhaust fan

  • air pump with 2 air stones
  • RX green solutions (which are low ph nutrients - 4.6-5.6 recommended)
  • changing the reservoir once weekly
  • small fan to help with stem strengthening

I’m 2.5 weeks into veg and I started noticing blotchy areas on the leaves about 3-4 days ago. The leaves are perky, green, and otherwise look pretty. The only thing I have done differently in the past week is add a CO2 pad - from The Green Pad.

  • light schedule 18/6
  • water temp 69-71*F
  • box temp 79-81*F
  • humidity 21-45% (spraying the cabinet walls multiple times a day - any other suggestions for this would also be helpful :blush:)
  • TDS 900’s
  • EC 1900’s
  • pH 4.7-5.5 (remember, I’m using low ph products)
  • plant height is around 5.5 inches

I was thinking it may look like nutrient burn, but not confident in that since all my numbers seems to be right on. Any ideas? Thanks for taking the time to help me out! I sure do appreciate it!

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More curious than anything… I read the instructions for the nutes and saw nothing about recommended PH, I certainly could have missed it. I feel like 4.7 is too low and 5.7 would be better but again, I just briefly read up on it.

Hopefully, someone reads this who has used it.

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Im not one of the big guys by any means but your ph needs to be at 5.8

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That’s clearly a pH issue, the low pH nutrients is only low in pH for conservation purpose or for very specialize plant such as swamp carnivor plant…It’s the capacity of the plant to absorb nutrients that you must take in consideration and in a hydroponic grow the pH must be between 5.5 and 6.1.

For your humidity problem, obviously a humidifier or a hang damp bath towel with a fan aim on it should do the trick or a couple of bowl or bucket of water either.

Hoping that’s helping you @Izzy

~Al :v: :innocent:

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4.7 is far too low and is almost definitely the cause of your problems, if you PH starts going to extremes it causes nute lockout and can cause deficiencies and toxicity in other cases as trace minerals like aluminum can dissolve if soil is too acidic.

When growing hydroponically your aiming to have you ph between 5.5 and 6.5.

Thank you guys for your advice on the pH. I know that the pH recommended by my product company is much lower than normal, and it has always been in the back of my mind. However, I have done a bit of research on RX green solutions and they seem like a reputable company with solid results. Since this is the nutrient solution that came in my grow kit, I am using it. And also hesitant to stray from the feeding recommendations.

Here is a link to their manual. Page 16 has a FAQ on why they like a lower pH.RX Green solutions: FAQ?Manual

Thanks for the advice on the humidity! I am going to try those tricks out!

I understand the are a reputable company but lets keep in mind some products are not Cannabis specific at lower ph levels lettuce and many other plants may be quite happy. As a reputable company they may not be targeting same plants as we grow :wink: just a thought. To me they look fairly healthy with slight signs of nute burn I won’t try and sell you on ph level but it doesn’t hurt to try raising it for few days to see if it does make a difference or not? try right before res change see if it helps any

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You’re welcome @Izzy

So , I have read the manual (the part that interest me the most) and you’re right, they seems to know their stuff, and the NPK and micro nutrients molecules are espacelly design to work at these low acidic level and for the cannabis plant to be able to process them, I find this intriging and interesting :grinning:.

Your plant seems to show calcium deficiency

, so, Calcium and lime in their liquid forms work well for fast absorption into the roots. Try using one teaspoon of hydrated lime per gallon of water and feed that to your plants. You will quickly see the results. However, I do not know if it’s gone a work at these low acidic level, this is a standard recommandation for standard hydroponic pH level (5.5 to 6.1) @latewood and @Aquaponic_Dumme are the expert in hydroponical growth, when they see the tag, I am sure they are gone a jump in :grinning:

One question, do you follow the feeding chart for light, medium or high dilution, if you are at light dilution, I am suggesting that you switch to medium, it’s possible that this is the problem :innocent: Or maybe it’s a slight misconversion in your dilution, so the exact amount in ml that you are putting in the reservoir will be helpful :innocent:

~Al :v: :innocent:

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They are @Donaldj, I was doubtful too but I have download the manual and they seems to know their stuff, it’s a specialized cannabis nutrients :wink::relaxed:

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Thanks Niala. I am using the feeding chart provided with the grow kit/nutrient solutions. I think its a standard dilution (I have seen some charts with less and some with more). Currently I am using 20cc of Grow A and 20cc of Grow B into 1 gallon of water. I will do that for one more week and then go to 24cc of each next week (res change is either today or tomorrow). I could technically go to 24cc this week but I was afraid that my problem was nutrient burn - not deficiency.

Also, could this be the reason its only affecting my biggest/most mature plant and not the two smaller ones? Again, thanks for all your help. Its nice to have someone to bounce ideas off of. :slight_smile:

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Absolutely, it’s a possibility, bigger plant need more nutrients and Calcium deficiency is a common problem in hydroponical growth. And you’re right on with the regular dilution. Some strains are hungrier in Calcium like WW and AK-47 for what I have read and it’s propably a good idea to try 24 cc/gallon and really shake well your bottle before using it and each time you using it. Sometimes, little detail like this can make the difference :grinning:

Oh! And by the way, this is what nutrients burn look a like.

Hoping that’s helping you @Izzy

~Al :v: :innocent:

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Yes @Niala , this is a ton of help! Very much appreciated, you seem to really know your stuff and I can always benefit from good knowledge. :slight_smile:

I will increase my concentration to 24cc of both Grow A&B when we change out the reservoir. Should I try that first for a few days before adding the hydrated lime?

Also, am I right to assume that my already damaged leaves will stay damaged even if I have corrected the problem?

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Yeap, always go step by step. And if it’s have not replace in 5 to 7 days, then go with the hydrated lime.

Generaly, damage done to the leaves gone a remain, however, by correcting the problem, the healty tissues will remain intact and the problem will not spread, if the damage is not too extant :relaxed:

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Are u using rx solution nutrients

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I have done 2 grows in the cash crop box with the same nutrients

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yes @Firstgrow! any advice? where have you kept your pH? what was your yield?

@lzzy

Wej
Welcome to ILGM

First i see that your plants look pretty darn good.
The reason they may be blotchy is due to being root bound.
A good way to tell is by the size of the pkant and the size of the cup you have them in.
Just simplly transplane then into their final home and they will spring back and look very healthy.
and they will reward you

Will

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@Izzy

This should help

Hydro and Soil less Mediums

Calcium gets locked out of Hydro and Soil less Mediums at ph levels of 2.0- 5.3
Calcium is absorbed best in Hydro and Soil less Mediums at ph levels of 5.4-5.8 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a Calcium Deficiency.

Solution to fixing a Calcium deficiency
To fix a calcium deficiency you can treat by foliar feeding with one teaspoon of dolomite lime or Garden lime per quart of water, Or Any Chemical/Organic nutrients that have Calcium in them will fix a Calcium deficiency. (Only mixing at ½ strength when using chemical nutrients or it will cause nutrient burn!)
Or you can take crushed up dolomite lime or garden lime in a gallon of water and water it in the soil. 1 to 2 teaspoons per gallon of water, which will be slow acting. Garden Gypsum, which is medium absorption. Limestone, which is medium absorption, Rock Phosphate and Animal wastes which are both medium/slow absorption. Note: Caution when using gypsum to an already acid soil (pH that is less than 5.5) can have a very bad effect on different types of plants by effecting the absorption of soil aluminum, which is poison to plant roots.

Will

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Thanks @garrigan62 , this is going straight to my note book

~Al :v: :innocent: