Lower leaves have spots, what am I missing?

[Roger-Dee]

Hi all! First ever indoor grow and I am having some problem with 2 girls out of 3.
I have a top-feed DWC Setup with a 40l reservoir. The strain is Glookies by Barney Farm.



I have just completed week 1 of veg and the last 2-3 days I started to get spot on the lower leaves. I did a water change 2 days ago and the problem is looking to be even worse.

I am using the Canna Aqua lines of nutes, and right now I have;
1.8ml / L of Aqua Vega (A & B)
2ml / L Rhyzotonic
2.5ml / L Cannazym
1ml / L Cal-Mag
This is the "low feeding chart" from Canna, and half the recommended dose for Cal-Mag.

The tank is average 6.0 of PH and I have 1.3 of EC (it was 1.00 before I added the Cal-Mag). Day temp is 75-78, night temp 68-72 and humidity is constant at 50%. Exhaust fan always on, air pump and top-feed also.

Judging from the chart online I determined I either have a P lack, Calcium or magnesium defiencies, or wind burn. I moved the fan away and added half concentration of Cal-Mag. 24hr Later it's looking to be even worse.

I guess I should add that until yesterday I had to adjust PH down from 3 to 5 times a day, it was going up about .1 per hour for the first week. Yesterday I added Cal-Mag to the mix and have only saw a small increase of .06 in PH over the whole night. Root also reached the tank about a day ago.

Any help or pointer would really help me!
Thanks a lot guys, and happy growing!

[Bud Lightyear]

Firstly I would drop the cal-mag from the rez, as you have discovered it raises the Ec which can lead to inaccurate feed strength reading. You can foliar feed your cal-mag, once a week will suffice...Right then, what's your rez temp, what's your background Ec and are the roots in the water, oh and what size is the gap between the net pot and water level ?


Regards BL

[Roger-Dee]

Hi BL,

Jealous of your username. So more information;
The BG EC is .13 and after adding my nutes I had 1.00 (2nd week of veg)

The roots touched the water about 24hr ago, rez temp is 79, pots about 1" from water with 5-6" of air on top.
Might need to set up a chiller on the rez?!

[Ivana_Groweed]

Is calmag not ment to be used later on in the flowering stage from what i am reading off my chart no expert mate that's just what am reading

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[Ivana_Groweed]

Is calmag not ment to be used later on in the flowering stage from what i am reading off my chart no expert mate that's just what am reading

Sent from my SM-J510FN using Tapatalk

patch that comment dude was reading the wrong thing lol

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[Bud Lightyear]

Hi BL,

Jealous of your username. So more information;
The BG EC is .13 and after adding my nutes I had 1.00 (2nd week of veg)

The roots touched the water about 24hr ago, rez temp is 79, pots about 1" from water with 5-6" of air on top.
Might need to set up a chiller on the rez?!

Your rez temps are way too high mukka, 79f equates to around 26c, at that temp you asking for trouble with pathogens and it won't have the ability to absorb or retain DO (Dissolved oxygen) The best temps for DWC or any other water culture system for that matter is around 18~19c...Your Ec should be around 0.4 above base for the stage of growth your at...

Regards BL

[Bud Lightyear]

Is calmag not ment to be used later on in the flowering stage from what i am reading off my chart no expert mate that's just what am reading

Sent from my SM-J510FN using Tapatalk

Soft water can need cal-mag supplementation at any stage of growth mukka unless there is sufficient already in the nutes that are being used....This is especially so with coco because it tends to hang on the the Mg but that's not relevant in this case as the Op is running DWC..


Regards BL