Strange spots

[Orion]

Problem: spots on older leafs

Medium/grow method: rdwc

Feed: and supplements used: mega crop

water source:tap dechlorinated with ascorbic acid

Strain/age: auto ultimate around 45 day from seed

light used: one auto cob 55w and seven 10w LEDs in a splitter

Climate: 75 to 80 degrees and around 60 rh

Additional info. The spots are on the older leafs so I wonder if this means the problem has been corrected. Water starting ppms less than 200. With feed, the ppms are now at 274. I guess I ought to mention that my meter uses the truncheon scale. Water temps are around 74 degrees. Total volume of water is 25 gallons. pH has been steady at 5.95 for about a week. @Mañ'O'Green what do you think?

 

[Orion]

Also I just lowered my cob. I can see a bit of taco on the newest leafs light cycle is 20/4

 

[Bob's Auto's]

Are you certain the ppm value is only 274? Looks like you have some serious salt build-up on your clay pebbles. Don't know if that's causing the problem? Young growth is looking fine, but the older leaves are showing the problem. Which suggests that it's a problem with a mobile nutrients (N; P; K; Ca; Mg).
If we compare your picture with this chart. It seems that it's a Cal/Mag problem... Are you using MC 1-part or 2-part?

Regards,

B

 

[Orion]

Thanks for the reply.
That's diatomaceous earth on the pebbles. I saw a gnat. Yeah I'm sure about the ppm. My meter uses the 700 scale I think.
I'm using the one part mega crop.

 

[Orion]

Do you think it could be related to the light? I've had problems with the calcium spots in previous grows and I've seen others who use cobs have problems with spots also. Maybe I'm barking up the wrong tree but I just lowered my cob and then this happen

 

[Bob's Auto's]

That's diatomaceous earth on the pebbles.

Ok, cool.

I'm using the one part mega crop.

I've read before that you need to use CalMag with the 1-part. Maybe @Mañ'O'Green can give some advice?

 

[Orion]

Ok, cool.


I've read before that you need to use CalMag with the 1-part. Maybe @Mañ'O'Green can give some advice?

That makes sense. Thanks for your help

 

[Mañ'O'Green]

You are way out of balance and your PPMs too low overall. All my work is in Hanna 500 scale so here is a conversion chart. So is the total of your starting water 200 PPM plus the nutrients 274 for a total of 474 or nutrients +water= 274 Truncheon?

The less Mega Crop you use the more out of balance it will be.

 

[Orion]

Water plus nutes equals 274. I looked at my notes and water started at 160ppm.

 

[Orion]

I'll up the amount of nutes and see what happens. Gonna do a res change in a few days also