Cal-Mag Deficiency?

Hi, first time growing in my new area. I am located in the rockies and am on well water. My water is horrible and has a PH of over 7.8, 500+ppm, and is VERY hard . So, I have never grown in this area and everything is different than the water I am use to at the beach where I could use tap water. So, I plant, germinate, use Fox Farms Ocean Soil, ph is 6.4, and I started with distilled water because mine sucks ass. I decided to buy an RO system and started using the RO with some left over distilled I had. This went on for a 10 days, with the last watering all RO (most in the last week was all RO). I was worried about Cal-Mag deficiency, so I did add 1/4 of a teaspoon per gallon on this last water of Earth Juice Cal-n-mag. This was two days ago and the last water. This morning I looked and two plants had spots on the (see pic). Grow room is 4.5x4.5 with 600w MH, good ventilation and kept at 75 degrees. Nutes is every other water and I use Fox Farms Grow Big. I have had great results in the past with my setup, till I moved here.

I read that with RO water you need to add a full teaspoon (it recommends 3/4 of a teaspoon on the directions) to offset the water.

So, first question is, is this Cal/Mag deficiency and, if it is, how to deal with it. I am going to keep using the RO water as my tab water is a disaster and not really an option. If it isn't, what is it and how do I treat it? Pic of spots is attached.

so the last thing you did was add the cal mag? so therefore if it gets worse and your still adding it then thats your problem, I would stop giving it the cal mag and call it good, You shouldnt try to fix problems that you dont already have.

-Jswett

I don't see a ca/mg problem, FFGB/OF is pretty loaded so you prolly won't have to add ca/mg till later in veg

IMO- Calcium Deficiency
Use the Cal/Mag once a month as a preventative. when you run into problems add it with every watering until the problem is fixed.

Good Luck with Your Grow.

Thanks for the replies everyone. I am a little confused now. I got one reply saying to not use cal/mag and one saying use it. I have only watered once with the Cal-n-mag. I mixed 1/4 teaspoon in 1 gallon of water with 2 teaspoons of Fox Farms Grow big. I noticed the Fox Farms Grow Big has some magnesium but no calcium. Also the plants are about 5 weeks old, maybe a little older, but around 5 weeks.


I found this site and the spots look most like calcium deficiency. I just started giving them nutes about 12 days ago and only added 1/4 teaspoon cal-n-mag on the last water. I doubt that too much cal-n-mag is the problem as I used 1/3 of the recommended amount in my water.

Here is the website-

http://www.thenug.com/galleries/diagnose-your-sick-marijuana-plants

At 6.4 you may be locking out Ca.


Here is a Ca def. I live in CO as well and have a very low EC from my tap water (.14) and have to supplement cal mag, I use coco blends which usually are more cal mag heavy anyways.

View attachment 2920419

Your soil has a good amount of Ca in it btw...a little extra Ca/Mg won't hurt obviously, if thats your only problem area just chill, maybe make sure your pH is in check, I know addin FF into RO can leave you will a pretty low pH

edit; damnit ibex beat me to it

Ibex, that pics looks real similar. Mine is only on 2 out of 10 plants. Not sure how long it has been there but I just noticed it today. Mine is just a few spots, maybe 2-3 on one plant and a little more on another. Might add 1 teaspoon of cal-n-mag to this next water. What do you guys think?

Now ibex, don't rep my shit if your not comfortable publicly liking it

Ibex said:

At 6.4 you may be locking out Ca.

Here is a Ca def. I live in CO as well and have a very low EC from my tap water (.14) and have to supplement cal mag, I use coco blends which usually are more cal mag heavy anyways.

View attachment 2920419

Click to expand...

Isnt he in soil though?

Yep, Fox Farms Ocean Forest. Used it on a few grows and it is amazing. I guess the reason I though Cal/Mag deficiency is because I have used only distilled and RO water, which I know has no nutes at all.

Hey If I were you I would look real close with a scope or some sort of magnifying device! I looks a lot like a bug problem to me (Spider Mites!) That's exactly what mine looked like, although I could be wrong because spider mite bites are tiny and I cant tell exactly how big the little dots are on your leaves from the pic. Either way you should check it out very closely!

Bublonichronic said:

Your soil has a good amount of Ca in it btw...a little extra Ca/Mg won't hurt obviously, if thats your only problem area just chill, maybe make sure your pH is in check, I know addin FF into RO can leave you will a pretty low pH

edit; damnit ibex beat me to it

Click to expand...

yeah that's what it looks like to me......PH fluctuations. If you want to confirm it's calcium, top the plant and inspect the stems center. Calcium deficient plants stems are hollow in the middle. Calcium will mainfest itself first as yellow dusting/peppering, then turn necrotic(dead patches usually brown or copper in color)

Magnessium will start as chlorotic (yellowing) of the leaf margins and starts at the tips of the leaves progressing towards the base. Yellow turns to brown and eventually the leaf falls.
Why don't you just used-chlorinated water and add some magnesium sulfate (Epsom salt) 1 tsp/gallon. Also dude you need to learn which elements are mobile and immobile, this will answer alot of your question with plant deficiencies.
FFOF has enough Ca and the only thing that you are most likely to run out of is Mg. Since it's a mobile element, deficiencies are more likely to show quickly and from the older lower growth. Ca is immobile and very slow moving and show in new growth.
Also too much K can displace and compete with Ca/Mg locking them out. And FYI a deficiency in N will antagonize a Mg deficiency.