Possible calcium deficiency on Dwc seedling. Need help identifying for sure

Ok so this is my 3rd dwc grow and i have never previosly experienced deficiency or toxicity problems..this is also my first grow in dwc using a plant from seed. (I usually got clones).. things have been going well. Explosive growth and im very happy except since 2 days ago i started noticing brown spots on older leaves and it has progressively gotten worse. I believe it is calcium deficiency but again i never had this issue so far..
I am vegging with a 300w mars hydro led
-Ph is a pretty steady 5.9
-PPM was 100 when i noticed the issue..it is currently at 200 ppm
-Water temp is 69°f during lights on and drops to about 67° during lights off
Air temp is about 75° during light on and drops to about 72° at lights off..
Thanks in advanced for the help

Tap or RO water?

I use only RO water

OK, that makes sense and you are spot on about the calcium deficiency. RO has no trace elements in it so plants grown in RO without supplements often exhibit what your plant is doing. A nice supplement of cal/mag on top of your normal feed will whip it into shape.

Ok thats what i figured and i bumped it from 150 ppm to 200 ppm. If anything i will bump it up as needed. Thanks a lot for the reply brotha!

I added 50 ppm of cal-mag

So Charles, you were already giving 150ppm of calmag? Then it's unlikely to be a calmag deficiency. You need to give as much info as you can when you first post to avoid this kind of confusion.

polishpollack said:

So Charles, you were already giving 150ppm of calmag? Then it's unlikely to be a calmag deficiency. You need to give as much info as you can when you first post to avoid this kind of confusion.

Click to expand...

I think he means 150-200 ppm overall according to his first post. He just added 50 ppm of cal/mag to that overall number.

Your gonna wanna get your water up to about 150 with cal mag to start off with and add 1/8 strength of your recommended nutrients for your plants stage of life since ro water get everything filtered out .
I’m just a noob tho so might work might not

Ok so i put the seedling in young and didnt wanna overkill so i had it at 50 ppm initially since seedlings still get nuitrients through the cotyldons (if i spelled that correctly)...after some observation of these brown spots i figured it was time to bump up the cal-mag so i did that bit it hasmt solved the issue. My ass is stupid cause all i have in it is calmag, sensi gro 3-0-0 and the clonex root maximizer. I forgot to get the P and K from NPK. After talking with other growers i think it makes total sense that it very well may be and P or K deficiency seeing as theres none lol. Im gonna grab some florablend or something in the a.m. to see if that will fix it...i definitely appreciate everyone chiming in to help save this baby. Shes gorgeous and i plan to mainline her. I will keep an updste of what happens with her

I'm sorry guys, but this thread doesn't make much sense. Here's my suggestion based on my experience:
Use Dynagrow veg fert, 7-9-5 if you can find it. For the most part you follow the directions on the back, except for one thing: when the plant is small it might be best to use kind of a low ppm, like 600. The instructions will probably say add one teaspoon of fert per gallon of water, but only do this until you hit 600 ppm and see how the plant does. This fert has a bunch of stuff in it and you probably won't have to add anything until you know for sure you need to. So don't go dumping a bunch of stuff in. I've grown plants to 6 feet in DWC using this fert. The max ppm is probably going to be around 1100 but it really depends on the strain and what the plant is telling you. Don't over do the fert. You could just follow the "teaspoon per gallon" rule as the plant grows and that will probably be fine. Use at least a 5 gallon bucket, go larger if you need to. You can cut a hole in a tote from Walmart and put your net pot in there if you need to.

The issue is still there. Im not sure if my ph was too low for this strain? I know im good on nutrients... Its starting as rusty brown spots that grow together and dry out the leaves and making them curl a lil bit. I thought initially it was too pow of ppm but thats when it started..maybe my ph needs to be higher?..idk if its just a lockout or what. This is boggling my mind. I put ph to 6.2 to see if that helps

Perhaps your mix isnt playing well together? Causing a lock out?

Just go with 1/4 to half strength of you base nutes only nothing else. Except mabey a small amount of cal mag (depending on how hot the nutes are)
And ph @ 6 for a few days. (This is a neutral ph range for nute absorption )
Remeber if it is cal it wont recover once the damage is done youll have to wait and see the new growth if i recall correctly.

The rest looks happy enough dont OVER luv it .

Hope this helps

Just my 2

Just an fyi i always like to give my girls a dilute bloom formula for the first week or 2 i dont wait for my cotlyden to die (mine survive till i chop mostly unless i fuck up)
I feed right when the first single leaves pop there head out (do not give over 1/4 strength or less)

This bloom mix helps with roots imo
Some seedling are more sensitive then others

pH fluctuates, trying to fight it is pointless. if you don't get dwc right, then just put them in ocean forest soil, add nothing but water, and see how they do.

My ph doesnt even fluctuate actually. It was a steady 5.8 and i bumped it up. I recalibrated my ph meter also..im stumped and the problem persists..its not cal or mag or K deficiency and its not bugs..i cant seem to figure it out man. I dnt believe it to be a ph issue either. Ive read a lot and theres many many people who have had this issue amd cant figure it out. Seems to go unsolved...idk what it could be..ive also ruled out heat and humidity issues as well as fungus..ive never foilar fed either until my attempt to solve it

if it's in the plants genetics, there's nothing you can do.