Which deficiency is this please?

[wix66]

Hi there

Into the third week of my first grow and need help on this please...

A few days ago one of the girls started showing brown spots on her lower fan leaves. This spread to covering the entire lower leaves brown and drooping. This has started on several of the other girls now as well. The rest of the plant looks good.

My set up is as follows:
* Temp - 26 degrees
* Lights - 2 x 900w LED's approx. 24" above
* Humididty - 35%
* 8 pot RDWC
* Res Temp - 22 degrees
* PPM - 500 (Tap water - 68 ppm)
* Lucas Formula General Hydroponics Flora Micro & Bloom @ 75% for Veg Cycle

I am on day 17 right now. After researching I thought this looked like nitrogen deficiency. I thought that the nutrient solution maybe took weak. So I added another 50ml of Flora Micro yesterday. But no change yet. Other areas it seems it could be are Cal Mag or Molybdenum deficiency.

 

[indica vet]

what is your ph?

 

[wix66]

Sorry, PH is 5.9

 

[TheRoach]

Act quickly on problems, but be moderate with your solutions.
That's something I learned in 420 magazine. Im not sure if adding more nutrients is the right answer here, I would go the other way around, giving less nutrients. That looks like ph problems, but I may be wrong.

 

[Stealthboat]

How much Calcium are they getting? With 2 900W LED's there is probably some serious growing going on, and I had heard that LED's cause plants to require more calmag or something. Your rez temp seems a little high at 22C, I believe it should be around 65F or 18-19C. ph 5.9 sounds alright, but that its the higher range cut off point of calcium absorption. Maybe aim for 5.6 for the next few days or so. The 35% RH is also kinda low, ideally you want it over 40%, even 50% for veg. Fix these few things and I bet you will see improvements.

 

[jojo677]

I had the same problem with the "rusting" and eventual browning of the leaves early on. It turned out to be a calcium deficiency due to a pH lockout. Do you know when your pH meter was last calibrated?

 

[wix66]

OK just got back from work. Firstly, A big thank you to you guys who took the time to help me out!

So I have taken action…

* Reduced water level in pots
* Raised Nutrient to 600ppm (Lucas Formula Veg 0-5-10)
* Lowered PH to 5.6
* Light Foliar spray

I've noticed it's like a jacuzzi in the pots. I didn't expect so much splashing onto the underside of the lids though. My net pots are 140mm deep. I have had the water level about an inch below this as recommended. I should have realised before that the bubbling if saturating the underside of my lids would be saturating the hydroton all the way up to and including the sponge. Hence why they look a bit overwatered I guess.

Does anyone think I should be adding Cal Mag to my feed or anything else? I have just been using GH Flora Micro and Bloom so far. I am hoping the increased micro and bloom nutrient, combined with lowering the PH, will address the phosphorous and calcium issues.

Roots seem absolutely fine to me. Good white pearlescent colour and pretty substantial for just over two weeks old I'd guess.

My DIY system if it helps is an 8 x 30 liters pot RDWC. I run a 10k L/H water pump and an 80 LPM air pump. I fill the pots with 20 litters and get a recirculation rate of about once per minute. The water to air ratio in the pots are 2:1 (20l water & 10l air).

 

[iwltfum]

It's a good thing for your res to be like a jacuzzi! The more oxygen in the water the better and less "over watered" they look.

I don't know if it should be completely soaking the medium. Definitely can be wet on the underside, but if you can pull a wet clay ball off the top... I don't know if it's ok for it to be that wet.

 

[TheRoach]

Do the roots look white and healthy?

 

[indica vet]

my system is constant top feed dwc ,they are consistantly wet and love it as long as plenty of jacuzzi action below

 

[iwltfum]

my system is constant top feed dwc ,they are consistantly wet and love it as long as plenty of jacuzzi action below

hmm. I guess I have less hydroton per plant then you. or I plant the plant deeper. If my hydroton is soaked through, my stalks experience moisture stress and eventually mold/mildew. Not saying this will happen to everyone, but just be careful about keeping the "transition zone" too wet (the place where the root turns into stalk).

 

[indica vet]

hmm. I guess I have less hydroton per plant then you. or I plant the plant deeper. If my hydroton is soaked through, my stalks experience moisture stress and eventually mold/mildew. Not saying this will happen to everyone, but just be careful about keeping the "transition zone" too wet (the place where the root turns into stalk).

mine are in 8" net pots, only the hydroton around root ball are soaked , it is no different than the roots sitting in the tub except the roots in the pot actually have a better gas exchange rate than those inside the tub. i have never had an issue with costant feed as long as it is highly oxygenated (dissolved oxygen).
and my growth rates are the fastest i have had on the last 5 grows
every parameter must be kept in check everyday