DWC - LED, 2 different plats, 2 different problems

[PickleRick]

-Problem: Brown spots on one plant, something else on the other.

-Medium/grow method: DWC

-Feed and supplements used:

Advanced nutrients
5ml Sensi Bloom A
5ml Sensi Bloom B
5ml Cal/mag
10ml Voodoo Juice
8ml Rhino Skin
8ml SM-90
250ppm

Same on both plants.

-Water source: RO/DI

-Strain and age
Auto-Bomb 26 days
Super critical auto 16 days


-Climate:
Day temps 25-28C, night 23-24C,
Res temps 21-24C
RH 40-60%

- Light used: LED 400w on 20/4. 60cm from the canopy.

-Additional info:
They both started showing problems early, end of first week-ish.

The auto-bomb I'd say has calcium deficiency. Second opinions?
Starting on the older fan leafs and moving up. Here are some pics during her development.

As you can see the lowest leafs are most affected, I belive those are the 3rd node leafs with the most spots. Removed the other ones earlier due to the same issue.

Here is from tonight at 26 days old.

------------------------------------------------------------------------------------------------------------------

The other plant, my best guess is phosphorus deficiency.
Starts out by turning the leaf to a darker green at the lower fan leafs, and the affected area is a bit..not mushy but softer then the rest of the leaf.
Then some weird markings show up, and later the crisp up.

And here is from tonight.

Any help is greatly appriciated!

 

[Waira]

-- hmmmm,...first thing, check the res' pH! nevermind what AN says, it never pays to be complacent about pH, trust me!...... yes it looks like Ca defc. to me too, but P defc. can show atypical symptoms sometimes that look similar to Ca defc.,.. usually they hit different levels on the plant though; Ca is poorly/non-mobile within the plant, P is mobile, meaning Ca dec, hits mid to uppers first and worst, P defc. usually lowers, but in bloom, can hit almost anywhere,... your plants are tougher call because of their young age/size,... I'm not an AN nute user, but the dosage looks OK, all the more weird,... lights may be too close, a powerful unit like that, young plants want less intensity,... LED put high demands for Ca too it seems,...rasie then another 10-15cm,.... check the Ca-mg product and make sure it hasn't gone foul,... otherwise, raise the dosage up, and maybe do a foliar spray,.. mind the N content in the Ca-Mg, if it's AN, it's high, and can contribute to N toxicity if overused,... Also. never cut the affected leaves off, this does nothing to help, in fact can hurt,.. mobile nutes are drawn from them, and if removed, the plant will just take it from other leaves,...nothing solved, more damage done,...

 

[PickleRick]

-- hmmmm,...first thing, check the res' pH! nevermind what AN says, it never pays to be complacent about pH, trust me!...... yes it looks like Ca defc. to me too, but P defc. can show atypical symptoms sometimes that look similar to Ca defc.,.. usually they hit different levels on the plant though; Ca is poorly/non-mobile within the plant, P is mobile, meaning Ca dec, hits mid to uppers first and worst, P defc. usually lowers, but in bloom, can hit almost anywhere,... your plants are tougher call because of their young age/size,... I'm not an AN nute user, but the dosage looks OK, all the more weird,... lights may be too close, a powerful unit like that, young plants want less intensity,... LED put high demands for Ca too it seems,...rasie then another 10-15cm,.... check the Ca-mg product and make sure it hasn't gone foul,... otherwise, raise the dosage up, and maybe do a foliar spray,.. mind the N content in the Ca-Mg, if it's AN, it's high, and can contribute to N toxicity if overused,... Also. never cut the affected leaves off, this does nothing to help, in fact can hurt,.. mobile nutes are drawn from them, and if removed, the plant will just take it from other leaves,...nothing solved, more damage done,...

@Waira Thanks for the response!
I'm on top of the pH, checking twice a day. Although I feel like I don't need too, AN pH technology really works, for me atleast.
I was thinking the same with the lights. They started out 90cm away. The company that made the light recommends 60cm in veg and 45cm in bloom.
So, gonna raise the lights. Change water in both buckets and up the ca-mg a bit.
I didn't know that about the leafs, will leave them on hench forth!

Thanks alot for all the advice!
Will update in a few days of how they react.

 

[MedGrower]

Hello @PickleRick !

Fellow DWC grower here. I've previously grown many grows with AN products and Canna -products and in my beginnings I had this exact issue. This seems to be more typical / pronounced issue with DWC for some reason, but I've managed to avoid it by making sure the EC of the feed is not too high (250ppm at that stage should be alright!) and that the pH is not too low. AN Nutrients also are so well chelated that it seems plants can use them up perfectly around pH 6.2 to 6.3 even, and that happens to be optimum for Ca and Mg also. Then again, I would suspect that a low feed such as you are using might set the pH around that ballpark anyway.

Rapid leaf material growth typical for DWC combined with low humidity conditions and proximity to LED light can put the plant under quite a challenge to maintain its leafs cells with a root system that is just developing. This may play a part on the seen symptoms perhaps? Big one that helped for me was to keep the pH at 6.2 / 6.3. I actually aim to keep the at 6.2 / 6.3 throught the grow and it works fantastic. Last harvest I did with Ultimate was yielding 1.6 gpw with LED.

 

[Rev. Green Genes]

Hello @PickleRick !

Fellow DWC grower here. I've previously grown many grows with AN products and Canna -products and in my beginnings I had this exact issue. This seems to be more typical / pronounced issue with DWC for some reason, but I've managed to avoid it by making sure the EC of the feed is not too high (250ppm at that stage should be alright!) and that the pH is not too low. AN Nutrients also are so well chelated that it seems plants can use them up perfectly around pH 6.2 to 6.3 even, and that happens to be optimum for Ca and Mg also. Then again, I would suspect that a low feed such as you are using might set the pH around that ballpark anyway.

Rapid leaf material growth typical for DWC combined with low humidity conditions and proximity to LED light can put the plant under quite a challenge to maintain its leafs cells with a root system that is just developing. This may play a part on the seen symptoms perhaps? Big one that helped for me was to keep the pH at 6.2 / 6.3. I actually aim to keep the at 6.2 / 6.3 throught the grow and it works fantastic. Last harvest I did with Ultimate was yielding 1.6 gpw with LED.

Great advice. I have not tried AN, I am using Green Planet Hydro Fuel (love it.) I agree completely about nute strength. I water plain water for a week, I don't go over 300 till they show sex, and bump up to 500 or 600 for the duration of the grow. I consider it a waste of nutes to do otherwise. With an exception or two, the plant will only take what it needs anyway. The rest gets thrown away? You will never have a problem toxicity this way. Any issues are either CA/Mg or pH.

@PickleRick Yours look like a combination of pH and light intensity. The curling leaves make me think the light is too close.

 

[PickleRick]

Hello @PickleRick !

Fellow DWC grower here. I've previously grown many grows with AN products and Canna -products and in my beginnings I had this exact issue. This seems to be more typical / pronounced issue with DWC for some reason, but I've managed to avoid it by making sure the EC of the feed is not too high (250ppm at that stage should be alright!) and that the pH is not too low. AN Nutrients also are so well chelated that it seems plants can use them up perfectly around pH 6.2 to 6.3 even, and that happens to be optimum for Ca and Mg also. Then again, I would suspect that a low feed such as you are using might set the pH around that ballpark anyway.

Rapid leaf material growth typical for DWC combined with low humidity conditions and proximity to LED light can put the plant under quite a challenge to maintain its leafs cells with a root system that is just developing. This may play a part on the seen symptoms perhaps? Big one that helped for me was to keep the pH at 6.2 / 6.3. I actually aim to keep the at 6.2 / 6.3 throught the grow and it works fantastic. Last harvest I did with Ultimate was yielding 1.6 gpw with LED.

Thanks for the response mate!

I read this about a week ago, just havn't been around. But I tried running my pH at 6.3 for 4-5 days now, and the plants show no sign of getting better, but not worse either.

My humidity since start has been between 40-60%, and now it's more like 60-70% due to lots of rain.

Thought about the LED aswell. When seeds broke the light was about 90cm from the canopy (manufacturer recommends 60cm veg - 45cm flower).
In the last week since they started stretching, the bigger of the two is closer to 40-50cm from the light, while the smaller is around 75cm from the light.
Leafs are not showing signs of light burn. ( @green genes )The ones that crisped up early on was just due to nutrients being depleted from the leaf, I'm quite sure of.

Here they are as of last night. The plant to the left is 10 days older, but was topped. So her sister out grew her. Day 29 and day 39.
Both are on the same feed.

15L water

10ml Sensi Veg A
10ml Sensi Veg B
12ml Cal/mag
10ml Voodoo Juice
8ml Rhino Skin
10ml SM-90
480ppm
pH 6.3

Happy Thuesday!! :smoking:

 

[MedGrower]

Thanks for the response mate!

I read this about a week ago, just havn't been around. But I tried running my pH at 6.3 for 4-5 days now, and the plants show no sign of getting better, but not worse either.

My humidity since start has been between 40-60%, and now it's more like 60-70% due to lots of rain.

Thought about the LED aswell. When seeds broke the light was about 90cm from the canopy (manufacturer recommends 60cm veg - 45cm flower).
In the last week since they started stretching, the bigger of the two is closer to 40-50cm from the light, while the smaller is around 75cm from the light.
Leafs are not showing signs of light burn. ( @green genes )The ones that crisped up early on was just due to nutrients being depleted from the leaf, I'm quite sure of.

Here they are as of last night. The plant to the left is 10 days older, but was topped. So her sister out grew her. Day 29 and day 39.
Both are on the same feed.

15L water

10ml Sensi Veg A
10ml Sensi Veg B
12ml Cal/mag
10ml Voodoo Juice
8ml Rhino Skin
10ml SM-90
480ppm
pH 6.3

View attachment 800176

View attachment 800177

Happy Thuesday!! :smoking:

Yeah the thing with Ca -defiencies is that the damage is permatent and often even when you correct the issue and feed more the symptoms can persist and are hard to rid off. Therefore it would be better to be pro-active about the issue after you are aware that this may affect your garden in the circumstances you are growing with. I know I have to avoid this issue like a plague myself always and at times it still manages to raise its ugly mug