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Magnesium problem need help

bigjdawg

Member
I have a constant magnesium problem that I can't figure out to save my life. Every time I switch to flower I have a magnesium problem that sets in almost right away and I have to battle it the whole rest of the cycle. I have used multiple mixes and every time it happens. I've used Lc's mix and dank Frank's mix and Coots. Same problem in all three mixes. I just need guidance on what I'm doing wrong and how I can fix it.

Currently im using lc's base mix #1 with 1 cup of dolomite per cubic foot.
Peruvian seabird guano 2/3 cup 12-11-2
Indonesian guano 2/3 cup 0-7-0
Worm castings 1 cup
Maxicrop 1-0-17 1tspn per gallon
Added to 5 gallons of dechlorinated water and brewed for 24 hrs. Used at every watering in flower

Even with the dolomite lime and worm castings I'm not getting enough mag. I even switched from wiggle worm castings to high quality castings I get at build a soil because I read that if you use high quality castings you should never have a problem with magnesium. That didn't help either. There have been cycles where I've added 1/2 a tspn of Epsom salt per gallon every watering and still didn't fix the problem. I've even recently been using genral organics calmag every other watering and it has helped some but hasn't fully fixed the problem. I thought about adding it every watering but I didn't want to make things worse with the extra calcium when I'm only having a magnesium issue. The only time I really see improvement is when I use Epsom salt as a foliar. That makes me believe that the soil is either deficient or for whatever reason the plants can't get the magnesium from the soil because something else is locking it out ? I am at a loss and don't know what to do to fix the issue. I am planning on dollar feeding one time a week with Epsom salt on my next cycle if I have to. Any help would be very much appreciated. I know the problem is in the soil and I just need help fixing it.
 

BurnOne

No damn given.
ICMag Donor
Veteran
Two questions just to cover the basics...
Are you using powdered dolomite?
Are the leaves pointing up like they're praying for magnesium?
Ementary questions I know but we need to cover all the bases.
Burn1
 

MJPassion

Observer
ICMag Donor
Veteran
I thought praying was a good thing?

Anyway,
It sounds like you've got a lot of bicarbonates in your tap water.
Bicarbs will lock out Mg.
It may also be the case that your plant just wants more.

Also,
Only foliar feed Epsom salts.
It'll cause soil compaction if added to you watering can.
Soil compaction will lead to other issues.
 

bigjdawg

Member
BurnOne: Yes it's powdered dolomite lime I believe the maker is greenway biotech. 22% cal 11% mag. It starts as yellow interveinial chlorosis on the lower older leaves and works it's way up. If it gets really out of had the leaves turn fully yellow and brown and fall off. I'll snap some pics tonight when the light comes on. I'm just confused why the plants can't absorb the mag. I know there is mag in the dolomite and the wotmcastings plus some in the maxicrop also.


MjPassion: would a water filter fix that if it were the problem. I know our local water comes from the river and is treated with chlorine.
 

BurnOne

No damn given.
ICMag Donor
Veteran
Usually with a Mg deficiency the leaves point upward. Yellowing is a sign of nitrogen deficiency. Pics will definitely help.
Burn1
 

bigjdawg

Member
Growingcrazy: I don't ph anything since I'm using dolomite in organic soil to buffer ph.

BurnOne: It has the interveinial chlorosis showing first. If I leave it alone or don't fix the deficiency then it progresses to the whole leaf turning yellow and brown and dying off. When I do use the Epsom salt the whole plant will green up and look good. I'll stop using it and the problem will return. Not right away but not long after stopping the Epsom salt. I'll definitely get some pics though since I'm sure my explanation isn't very good
 

Limeygreen

Well-known member
Veteran
I would either do a water test for mineral content and pH or use ro water/spring water. Just because you us dolomite doesn't mean your pH of you water and soil don't matter, what is your soil pH? too low of a pH will also cause mg lock out, it's not available at those low pH's. P will also cause lack uptake lock out of mg if you have too much, too much sulfur as well. The browning you speak of, it starts as spots correct?
 

bigbadbiddy

Active member
I'll be honest: I just skimmed over this.

BUT:
I think I have the (albeit simple) solution for you since I ran into something very similar.
I run organic soil, the plants looked great in veg but in flower, way too early, they started to show various deficiencies.
I narrowed it down to N and Mg deficiency by doing some research online.

And while my plants did indeed need more N in particular and Mg as well (I later changed the ratio of my soilmix to include 1 more part of EWC --> N deficiency fixed since - and a bit more epsom salts --> Mg deficiency fixed since), the deficiencies were caused much more by me not PHing my water.

I also believed that my soil would do the PHing/buffering for me, the dolomite lime etc. etc.

This is not inherently wrong, the soil does that for you, to a certain degree.

What I later found out was that me adding Canna Bio Rhizotonic and/or Bio Boost was what caused my water PH to go all out of whack and the nutes starting to be locked out.

So my soil mix could use some more EWC and Epsom Salts at that point in time but that was not the main culprit.

The main culprit was me not PHing my water and using chemical nutrient additives on top of the organic soil (which further threw the PH off).
The PH was likely way above 7 over long periods of time and at that point all kinds of nutes get locked out.
I am honestly surprised at the quality I pulled without PHing my water.


I have since adjusted my habit and PH before every watering to be in the 6.3 range and the plants are very happy with it.
I do however need to add EWC to my water and make a slurry or after about 3 waterings the plants face an N deficiency again. Like I said, I remedied that by adding 1 more part of EWC to my soil mix since then.



So long story short:
PH your water. Until you do, you can't tell which nutes are simply being locked out and which you actually need to add.
 

bigjdawg

Member
These are all in dank Frank's mix I was thinking there might be a slight potassium problem on a couple also I did add some maxicrop soluble powder tonight
 

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bigjdawg

Member
These ones are still in veg. These are in lc mix #1and guano tea recipe. I prefer the lc#1 and guano tea recipe over all other mixes so far. I've tried multiple mixes with the same main problem. From here on out I'm focusing on one mix and it's going to be lc#1 with the guano teas
 

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bigjdawg

Member
I don't ph because everything I read said you don't need to in organic soil since the soil buffers it's self from the dolomite lime. That's the reason why I haven't done so

If it was my water source would a normal water filter remove biocarbonates? Or would i have to buy a special water filter or start buying ro water?
 

bigjdawg

Member
I have had great success with the lc mix #1 and guano tea recipe. I grew this one in that mix but I still had the same mag problem. I even started to add 1/2tspn per gallon of Epsom salt to the nutrient teat and it didn't help. I only saw improvements with a foliar feed of Epsom salt. This by far was my best cycle though. I just got tired of the on going mag problem so I switched to dank Frank's mix to see if a new mix would suit me better but now I'm seeing the same thing so im returning back to lc's mix but trying to find a solution for when I switch from veg to flower on my next cycle. Plus trying to fix the current problem in dank Frank's mix since I'm only on week 2 1/2
 

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I wood

Well-known member
Similar deficiencies plagued me while transitioning to recycled soil. After reading slownickel(I think) go on about the importance of calcium in several long and detailed posts I started topdressing with gypsum. Things started getting better quick. I now add a spoonful when remixing soil and top dress at transplant as well.
If I recall correctly, calcium plays a role in the absorption and transport of many other key things.
It is cheap and easy to get, worth a try in my opinion.
Good luck.
 

hyposomniac

Active member
I don't ph because everything I read said you don't need to in organic soil since the soil buffers it's self from the dolomite lime. That's the reason why I haven't done so

If it was my water source would a normal water filter remove biocarbonates? Or would i have to buy a special water filter or start buying ro water?

That might be true of a real organic soil but most indoor people, myself included, are just running organically amended soiless mixes in small pots and calling it organic soil in the hopes that it one-day becomes one.
No a regular filter will not remove bicarbonate.
Manufacturers suggest RO filters will remove 95% of bicarbonate but I can't locate real data.
 
G

Guest

Im no expert but I only use RO water now or occasionally mix my RO with tap water 50/50. My tap water has crazy high alkalinity. Plus I personally think way to many people reach for epsom SALT way to often and early.
 
G

Guest

That might be true of a real organic soil but most indoor people, myself included, are just running organically amended soiless mixes in small pots and calling it organic soil in the hopes that it one-day becomes one.
No a regular filter will not remove bicarbonate.
Manufacturers suggest RO filters will remove 95% of bicarbonate but I can't locate real data.
Even the cheapo paper test strips will show how much crap is removed from RO water compared to any tap water. Ever wonder why so many homes have them for ice makers and coffee use etc. ? If you cant locate REAL data try google. Im not going to do it and link hundreds of links for you.
 

Dog Star

Active member
Veteran
Use 2 caps from a bottle of apple cider on 5 gallons of water to lower down PH,

if you are in organic setup that doesnt mean you dont need to lower a PH of
your feed.. with lowering a PH a plants will eat a lot easier and will not lock Mg..
 

PakSamGyiShing

New member
Sulfur

Sulfur

Similar deficiencies plagued me while transitioning to recycled soil. After reading slownickel(I think) go on about the importance of calcium in several long and detailed posts I started topdressing with gypsum. Things started getting better quick. I now add a spoonful when remixing soil and top dress at transplant as well.
If I recall correctly, calcium plays a role in the absorption and transport of many other key things.
It is cheap and easy to get, worth a try in my opinion.
Good luck.

I think I Wood is onto something with the gypsum, it'd be worth you running a trial. Back in the ROLS thread Coot and them all would rag on folks running dolo lime, and all the fellows dealing with Cal-Mag lockout issues. At one point he mentioned that this situation is incredibly common in folks running in coco setups because coir is incredibly deficient in sulfur. The sulfur is used by the soil microbiological community to break the carbonate bonds on both Calcium carbonate and Magnesium carbonate, making both Ca and Mg available. Without the sulfur, as sulphate, playing this role you can get these lockout issues. It may be good to try and top dress with some gypsum and see if that helps.

Switching your overall lime mix to something like 1 part dolo:1 parts ag lime:1 part gypsum, and then using 1 cup of this/cf of your soil may help. This would be 26%Ca, 4%Mg, 5%SO4, with a Ca:Mg ration of 7:1, which is aight. The 2:1 ratio of the straight dolomite lime is quite a bit off from what you want, being about 22%Ca, 11%Mg.

HTH
 

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