Calcium and/or magnesium deficiency?

@PharmerBob @Drinkslinger

Can’t get a good picture at the moment but does this look like a calcium or magnesium? I had a regular water feed yest. Should I wait 2-3 day for it to dry and go ahead with scheduled.nute feed or should I water with calmag now? 4 week in

flower. TiA

Is that the only leaves on the plant that have those markings?

@imSICKkid no there are a couple more like that thru out the plant

What medium are you in? Do you use tap water?

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FFOF and no, distilled and pH at 6.5

I’m guessing it’s this. I haven’t used calmag in a couple feedings. Just the other in the GH nutes

But should I wait til next feed (which is scheduled to be nute feed) or do I water with calmag when light come on. I know soil will still be moist but do you let that continue for a couple days while soil drys

If your not adding any nutrients to your distilled water then you dont need to ph it. The plain distilled water will instantly match itself to the ph of your medium. Since the R/O water has little to no solids in it, it can’t hold a stable ph. Now, once you add nutrients to the distilled water…then you ph it.

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I think your ok letting it dry out a few days and then go for it!

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Thanks, I didn’t know that. Definitely will make regular watering easier. Thanks for the help too

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No problem. That could also be the root of your problem. By trying to PH the distilled water down you may have locked out your cal/mag by creating water that is to acidic or to neutral. Just make sure to check your runoff numbers next feed to see where your medium is at

This is how it was explained to me.

Calcium is an immobile nutrient in cannabis plants meaning that your plant can’t take from other parts of itself to supplement for a lack of calcium. This is why new growth is affected.

Magnesium is a mobile nutrient in cannabis plants meaning that the plant has the ability to take magnesium from other parts of the plant (usually the older lower growth) to supplement the new growth.


Should I run non ph’d distilled water to bring the ph up in the soil?

Nope. If your trying to be at 6.5…then you would run 6.5 water through it until you reach your goal. If you wanted 5.8, then you would run 5.8.

Remember, the distilled water will match the medium instantly. So flushing with plain R/O water will essentially get you nowhere.


Since you’re using distilled water, I’d put cal mag in every nute solution until around the 5th week of flower.
At that point I start tapering off the nitrogen. Most cal-mag supplements contain nitrogen. Which you don’t want near the end.
I throw epsom salt in during late flower for increased terpenes, and that takes care of potential late stage magnesium issues.
I have earth juice “oilycan” which is a nitrogen free cal mag supplement. Just in case.


What’s your ratio for e.salt to water

For just maintenance use, 1/2tsp per gal.


Usually Normal tap and well water contain trace elements like Calcium and many trace nutrients where the distilled water is stripped of all that. So if using distilled or RO you have the job of adding all that the soil critters need to help feed the plant. If your running living soil don’t sweat to much with all the overwatering to run off and Ph and PPM checks they become much less important in the process.
If using tap or well or a combination of say tap and RO or distilled (I now use a 50/50 mix myself as my straight tap has too much so I have been mixing before adding any amendments like epsom salt or such but I do check Ph of final solution before watering to keep it in the 6-7.2 range) this could save you some hassles and money buying distilled water.
Living soil will self adjust if you have a healthy micro herd in there.
There is a difference in actual soil Ph to the Ph of water run off! If checking soil Ph use a decent $50 soil probe that will give you pretty accurate soil Ph readings. The pen type Ph meters for testing water run off won’t tell you soil Ph just what drains out and they can and are quite different.
I have a post on here about soil probes and all if your interested.

As far as the spots on leaves go just keep an eye on them and see if things are progressing and correct.
Slow roll with live soil.
As mentioned adding epsom salt 1/2-1tsp per gallon is a good cheap way to provide the soil with magnesium and sulfur.
CalMag are 2 additives Calcium and Magnesium and they do go hand in hand at times but both aren’t always called for or needed all the time or at the same time.


Yeah what they said!

A lot of the calcium in tap water isn’t available to the plants even when it’s there. So even when using tap water best to keep an open mind and treat as you see. Sometimes they will fly, sometimes base nutes will cover demand, and sometimes they need a little help.