Brown Spots and Yellowing Leaves in Flower

-What strain, Seed bank, or bag seed (photo or auto) Photo Granddaddy Purple from ILGM
-Age of plant: 5 weeks into flowering
-Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF: DWC Hydroponics
-Vessels: Type and capacity of container (fabric, plastic, etc): Black plastic 5 gallon bucket
-PH and TDS of Water, Solution, runoff (if Applicable): 5.6-6.2
-PPM/TDS or EC of nutrient solution if applicable: 2.1
-Method used to measure PH and TDS: Digital meter
-Indoor or Outdoor if indoor, size of grow space: Indoor in a 3x3 grow tent
-Light system List brand and wattage/spectrum: Spiderfarmer SF2000
-Actual wattage draw of lights
-Current Light Schedule: 12 on, 12 off
-Temps; Day, Night: 65-74 degrees
-Humidity; Day, Night: 60% consistent
-Ventilation system; Yes, No, Size: Yes. AC Infinity Cloudline T6.
-AC, Humidifier, De-humidifier,: No
-Co2; Yes, No: No

My fan leaves are getting brown spots on them. Then they turn yellow. The brown spots seem to kill the leaves and I’m not sure if it’s a calcium issue or a magnese issue or both. This is my second grow and both had this issue. The buds are unaffected and look healthy.

Should I cut off the affected leaves or leave them?

Thanks so much for the help!!


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I should mention that I’m using the Foxfarm nutrients and am following their hydro schedule.

The water is changed weekly and kept at about 65-68 degrees.

The affected leaves won’t get any better so do with that as you will. You have a couple issues going in it looks like. I like to refer to these charts when I run into issues


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Big calcium deficiency and most likely Magnesium. Do you supplement calmag? Are you growing in soil or hydro? Confused on the support ticket. 5ml of calmag with your regular nutrients. If your EC is 2.1, that comes out to roughly 4000 PPMs and way high. You should be around 1000 PPMs. What nutrients are you using. If those numbers are accurate, I would flush several gallons through her with just calmag and follow up with 1/2 the nutes and 5 ml of calmag :love_you_gesture:

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Thanks for the feedback. So I’m growing in DWC hydroponics. I’m following the Foxfarm feeding schedule. I don’t use calmag but will definitely get some and add it as per your instructions.

According to the schedule for hydroponics, my EC should be 2.1-2.3 which I’m definitely in the range of.

I just changed the water on Sunday and added fresh nutes.

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I believe its a phosphorus def i would make a banana and cucumber skin tea .get four skins from four bananas and take the skin off one cucumber cut it all up in to smaller pieces place in a stocking or something place in a 20ltr bucket of water and bubble for 24 hours and then feed this is great for flower stage it will boost ur potassium and phosphorus levels and it will help for bigger and healthy flowers

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That feed schedule for the 2.1 PPMs includes every nutrient in the schedule. Base nute feeding of the Grow big or Big Bloom should be around 1000. Your ca lol and grow​:love_you_gesture:. Good luck with the rest of your grow :crossed_fingers:

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Just out of curiosity, you’re using the 500 scale on the TDS pen?

Thanks for all the help! Here is the meter that I’m using and the setting it is on:

If I was measuring PPMs I would use the 0.5 setting.

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What do you mean when you say bubble for 24 hours? Does that mean leave everything in the water for 24 hours or boil it for 24 hours?

Usually when they say bubble they are talking about putting air stones in a bucket with water and whatever else and leaving the air stones on for 24 hrs

I’ve seen Mr Canucks use the teas a lot and would definitely reccommend you watch his videos on it if you don’t know much on the topic. Mr Canucks grow on YouTube. When I ran fox farm I was using a 3 to 1 dilution as the fertilizers are hot but take that as you will as I was growing in coco coir

U use a air pump from a fish tank to bubble the water for 24 hours no heat involved

Thanks for clearing that up. This is my second grow so I still have a ton to learn. So far I’m seeing a few different solutions to my issue.

  1. Calcium def
  2. Phosphorus def

Which one should I try first? In other words which one has the biggest effect on the plant?

You need to check the NPK on your bottles should be like 1-0-0.5 or something. These three numbers form what is called the fertilizer’s N-P-K ratio — the proportion of three plant nutrients in order: nitrogen (N), phosphorus (P) and potassium (K). The product’s N-P-K numbers reflect each nutrient’s percentage by weight. So if you aren’t already you need cal mag to add or of you are then up the amount per gallon and or some form of calcium if your organic and you need to look at bottle nutes and add more of P to your mix

Cal/Mag deficiencies have very detrimental effects on the health and growth of the plant. Phosphorus is most important during flowering/fruiting, so both are pretty important. Everything below is based on the assumption that you have a Cal/Mag deficiency, (along with phosphorus) so take careful stock of your nutes before taking action to determine if that is the case.

Day 1: Add Cal/Mag at 150% recommended dosage on the label to plain water (RO or tap that has sat out for at least 24 hours)

Day 2: Keep Cal/Mag at 150%, plain water with a half dose of bloom nute high in phosphorus,

Day 3: Cal/Mag at 150%, plain water, with Bloom nute. The solution should not go beyond an EC of 1.2 or so. If you have fulvic acid, add a little to the mix. And watch your PH… Don’t let it drop below 5.8.

Day 4: Return to full strength solution, making sure you adjust for the added Cal/Mag (now at 100% rather than 150%). I would recommend not going higher than 1.6- 1.8 EC… Your plant can only use so much.

This is only what I would do in your situation, with the limited knowledge I have of your grow. Take it with a grain of Epsom salt… lol

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Also: Adding a mycorrhizal inoculant (tea or supplement) with appropriate food, along with pond enzymes (5 drops per gallon) will always help. (Just be mindful of gunking up your DWC). There are tons of threads in this forum about microbes, so take advantage of that as well. Good luck with your grow.

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Thank you all for all your help! l love the forum and this community and I feel very supported here. I thought that since I’m using the Foxfarm nutrients and feeding schedule that that would be enough for my plants. Is their feeding schedule too aggressive on the nutes? They say that in flower the EC should be 2.1-2.3. Based on what everyone has posted, it looks like it’s too much. Is there a better guide to using these nutes?

FF’s feeding schedule is high. I started with the FF trio at 1/4 strength then bumped it up to 1/2. I got tired of flushing my plants using these nutrients and switched to jacks 321.

Absolutely too high. Your medium will have major salt build-up in no time. I have never grown a plant that needed more than an EC of about 1.6. Depending on your conversion chart, that is around 800 to 1100ppm. A lot of these companies really push this notion that your plant will starve if you give it less. Not true. In my last few grows I rarely went above 1.3- 1.4. Now, if you are using CO2, and bright enough lights, the threshold is higher. There are also some really hungry Sativas out there, but even those outside of CO2 enhancement can’t make use of much more. The unused salts build up and result in the roots struggling to continue osmosis, and in fact, enough build-up will lead to reverse osmosis, meaning water is being pulled from the roots into the medium.

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