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Magnesium problem need help

BigPete

Member
I grow in coco and always had yellowing of the lower leaves no matter what I did I couldn't cure it epsoms, calmag, it just made matters worse. My present grow I add a couple of drops of superthrive to every watering and 5 ml of seaweed extract [drain to waste} and I have lush green all over. I use aqualakes A&B
 

hyposomniac

Active member
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.

Just saw this post and it stuck me as odd.. I wasn't asking you to locate anything for me, in fact I just got done reading about RO bicarbonate removal on Google when I posted that. Not sure why the 'tude buddy; I've never asked you to do anything for me, but I guess you and you test strips are chemistry experts now so I will direct all future questions to you.
 
I moved to a new city this year and started getting my water from a dispenser that advertised it as filtered. I thought that should be good enough since i only filtered the water I was giving them when I lived out in the country. Turns out this city water is toxic to life even when filtered.
 

growingcrazy

Well-known 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?


You are correct in thinking that the soil will buffer the pH once you have watered. The missing portion is knowing what the soil pH is at so you know what your solution pH will settle to(buffer).

If you add 7.8 tap water to a 7.6ph soil, not much pH change will occur. Your stuck at that pH and limiting nutrient availability. If you get lucky and have a high peat mix that is at a pH of 5.8 and then you water in that 7.8 tap water, you might get lucky and land at a good pH range in solution.

If you adjust your pH from the start you are giving your roots the chance to be surrounded by the proper pH from the moment of initial watering.

Use the lime to increase your soil base mix pH to mid 6's. Set water pH to 6-6.5.

Test the soil and your water. Adjust accordingly.

I am going to say this... Everyone was wrong when they said not to pH your water in the past.
 

bigbadbiddy

Active member
It's just a misunderstanding of terminology.

The people saying you don't need to PH your water in organic/living soil are talking about outdoors where there is so much soil and water and space that there is more than enough buffer for any water PH level you might use, safe for Flint water or the like.

But even if you use organic soil indoors, you still do so in a pot or small bed and there is simply not enough soil to buffer any PH you may throw at it.

While outdoors the soil can deal with any PH water, in your indoor setup, the organic soil can maybe buffer anything up to PH 7.8 let's say. If your water comes out the tap at 8.0 we have a problem and nutes will get locked out.

I personally did not get reliable readings from my cheapo "soil PH meter" as well as my water PH meter and had to simply test it out. But you water your plants often enough and just have a look at them and see how they react.

My water starts at a PH close to 8 which I previously lowered to about 6.5 which was a huge step forward in terms of plant health. But I noticed that I had no adverse, rather more positive effects, by lowering PH even further. I am now aiming at a PH of 6.0 for my water and will likely test going as low as 5.8 or 5.6 or something.

My soil has a PH somewhere north of 6, maybe even 7. So the water naturally has to be lower PH to land somewhere near 6 where no nutes are locked out (afaik).
 
M

moose eater

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?

I've only read through to post #13 thus far, so forgive me if I'm being redundant or obtuse.

I ph everything I plant, including the raised beds in the outdoor main veggie garden. I use mostly organics, a bit of 'natural' and minor soluble most of the time. I ph everything, and there's a difference in the outcomes.... -no- -doubt- .

Only recently did I go back to ph-ing the (water/liquid feed) regularly; I hadn't done that real regularly in years. Still don't for the veggie garden... but I also know my well water ph, and test the soil in the beds, shocking the garden outside every few years with agricultural sulfur to address the calcium carb in my well water.

Your posted k values in the maxi-crop looked suspect or in error to me, but who knows?? (*That was just an observation and is neither here nor there, really).

The pic on the far right at the bottom of the first page, however, is what I interpret when I see it in my plant color as maxed or excess K that hasn't yet worked its way into a catastrophic state yet, but is capable of getting there with some 'help.' That green hinging on greying a bit...

But I could be wrong, too. I am more often than I'd like to think..
 

hazyfontazy

Active member
Veteran
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?



in coco ive fixed this problem by using a brita filter /and or bottled water ,was a nightmare :(
 

growingcrazy

Well-known member
It's just a misunderstanding of terminology.

The people saying you don't need to PH your water in organic/living soil are talking about outdoors where there is so much soil and water and space that there is more than enough buffer for any water PH level you might use, safe for Flint water or the like.

But even if you use organic soil indoors, you still do so in a pot or small bed and there is simply not enough soil to buffer any PH you may throw at it.

While outdoors the soil can deal with any PH water, in your indoor setup, the organic soil can maybe buffer anything up to PH 7.8 let's say. If your water comes out the tap at 8.0 we have a problem and nutes will get locked out.

I personally did not get reliable readings from my cheapo "soil PH meter" as well as my water PH meter and had to simply test it out. But you water your plants often enough and just have a look at them and see how they react.

My water starts at a PH close to 8 which I previously lowered to about 6.5 which was a huge step forward in terms of plant health. But I noticed that I had no adverse, rather more positive effects, by lowering PH even further. I am now aiming at a PH of 6.0 for my water and will likely test going as low as 5.8 or 5.6 or something.

My soil has a PH somewhere north of 6, maybe even 7. So the water naturally has to be lower PH to land somewhere near 6 where no nutes are locked out (afaik).

The key with outdoors is that rain water is generally acidic. You could water multiple times a week with high pH, high bicarb water and then get one good rainfall a week at 5.7 and things are fine.

I use a pH probe and doser in my res. for indoors. Keep the pH at 6.2 at initial flower, rising to 6.6 or so at the end of flower. Set the dial and walk away, no more pH concerns. My other addition is a weekly soil drench with fish hydrolysate that is usually a low pH, somewhere in the 5.2 range. That weekly pH swing keeps the entire array of nutrients available in solution.
 

bigbadbiddy

Active member
TIL about PH probes and dosers.

Bit pricey for my wallet but maybe I am going to start hitting up the neighbors who used to have pools. Maybe I get lucky ;)
 

bigjdawg

Member
Well I thought I would share an update. I bought an RO filter and I thought this was going to be the solution. I started watering with ro water right at the flip cause that's when I received the filter and the small mag problem I had cleared up. I was really excited and thought I found the solution to my problem. Then the dreaded started happening at week three. Here comes the mag issue again. So now I'm back to being frustrated and don't know what the problem is. It's magnesium every single time and it doesn't matter what mix i run. I even seen it when I ran coots mix one time. I know there is mag in my worm castings the maxi crop and the dolomite lime I used. Maybe the plants still want more idk. I still haven't messed with ph that's my next step but honestly I don't see how if it was ph I would only be having a mag issue and nothing else. I don't really think that's it. I'm going to work on it though. If anyone has any other ideas I would appreciate it
 

bigjdawg

Member
Some photos
 

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bigbadbiddy

Active member
Ok, theory time:
I would say it is theoretically possible that just Mag gets locked out by your PH values.
If that is actually the case... There is a thread on deficiencies here on the board which also mentions at what PH what nutrients get locked out. You could theoretically consult that thread.

Anyhow:
If you think it is still Mag that is missing, why not just add some more then? You can water it in, you can topdress it and see what happens. At worst you burn your plants and have to work in the opposite direction or, absolutely worst case, reset entirely.
Which imho isn't much worse than a bad harvest.


The yellowing on your leafs, to me, could also be a N deficiency. Maybe try give them some more of that and see how they react.

I can tell you that on my end, I was searching deficiencies for almost a year, preceded by trying to figure out how I got fungus gnats that killed everything.

Ultimately I gave up and did a complete reset, including 2 months of downtime (no growing at all).
I didn't even adjust the soil mix drastically but I did create the hypothesis that it was the additional bio canna nutes I used that caused the root rot and fungus gnat explosion and that was my main issue.
I also theorized that likely not the nutes themselves were the culprit but what they did with the water I gave to the plants, meaning the PPM and PH were all out of whack from using the additional nutes.

So I decided to use only water for this run, after resetting everything. And PH the water for the first time.

And looky here, the plants look great, everything worked awesome.

What I noticed was (similar to you?) that there must still be a deficiency in the soil because I had yellowing leafs starting from the bottom and bottom growth being stunted and tiny before yellowing, dying off and then trying to grow again.

I thought about it, went online and asked questions etc. etc. and ended up narrowing it in to a N-deficiency.
So I simply tried it out.
I topdressed with a gentle helping of EWC and sure enough, the plants looked way better in flower and the yellowing from the bottom and tiny/stunted growth from the bottom of the plants stopped entirely for several weeks.
Now, a lot later in flower, they are appearing again, I have yellowing here and there and some of the plants reacted with burned tips and clawed leafs (very few) so they probably got a bit too much N from the top dress. But most plants really liked that step.

My plants in veg however, were still in the same soil mix as before. The one I since knew was N deficient.
Unfortunately I didn't have any EWC anymore to remedy this so I used bloodmeal instead. Since I didn't want to topdress pure bloodmeal (the smell ...), I took a bit of the new soil mix and enriched it with even more bloodmeal and topdressed that.

The plants loved it and the current veglings are among the healthiest I have had so far.


So:

My advice? Simply go with it and try it.
If you agonize too long over it without actually trying something, you will get nowhere and just loose time.

Do something, even if it risks losing your current crop. At least you will know you need to work in another direction then.
But nothing is more frustrating than waiting for an answer and seeing no change when applying the various solutions mentioned by people online.

It's your garden, they can't really help you in the end. They can inspire you to find the solution, they can nudge you in the "right" direction but in the end, you will have to find out.

In case of my fungus gnat infestation:
Only after about half a year of tips and tricks and suggestions of how to handle them, discussions if they were root aphids after all etc. etc. etc.
Only then did someone mention, as a sidenote, in passing, that it might be from the whole synthetic nutes in supersoil conundrum.

That still wasn't exactly the answer but it steered me in the right direction, the direction where I question my water, my PH values, consider that nutes are locked out and roots beginning to rot as a result of nutelock in constantly damp/wet soil.
I believe I was basically watering them and the water would just sit there because it was too salty/acidic/basic/whatever for the roots/plants to do anything with. Since they were surrounded by soil and water but couldn't drink any of it, they just withered and died or some of them barely pulled through with bad results.

But I had to figure that out myself in the end.

And I am still not 100% sure I have actually figured it out or just got lucky so far in the second round.

We will see :)

But just test it man. Topdress/add some Mag, maybe also N...
 

Limeygreen

Well-known member
Veteran
I have around 9% saturation of mag with 85% ca with no issues, watering in Epsom week 3 and week 5 at 1 tsp per gallon. My pH is around 6.4 and no dolomite lime added. A couple things I could think of, soil is too wet and your roots are having problems with uptake, roots could be too cold as well. Could also have to do with your P levels locking it out or potassium levels being too high blocking it out. If you had been watering with the old water in veg and only switched to ro at start of flowering you could have a build up of whatever it is in your soil from old water causing the problem. The best way is to test your soil and see what's there, in the mean time I would drench in some Epsom salt next watering and try to go a bit drier on your watering.
 

bigjdawg

Member
I watered two with go calmag. I'm watching for signs of improvement. Then I got three others I'm going to give a good top dress of worm castings and compost when they need to be watered again. I let them dry out a good amount. I lift the pot to see if there ready for water. Ya I've heard the high phosphorus can lock out mag but I also heard it would lock out other micro nutrients first. I did switch water at begining of flower. I had a small mag issue then and I didn't add any nutrients but when I switched the water the mag cleared up all on it's own. That's why I was thinking the ro water would fix everything but then it returned
 

Dave Coulier

Active member
Veteran
Some photos

Thats not a Mag issue, thats a N issue. Your plant is suffering from low levels of Nitrogen. Its very common to experience this problem after 3-4 weeks into flowering if you dont continue to supply enough N, and you say this happens consistently at 3-4 weeks in??? Thats not surprising because the very same thing happens in my garden too if I fail to feed my plants enough N.

I dont know how close you keep your plants to the lights, but if you can keep your lights further away, you'll experience N deficiency setting in later in flower, rather than earlier. It may seem odd to move the light further away, but keeping fan leaves healthy and green is the priority #1. It takes some experimenting to find a good balance, but it does help alleviate N deficiency symptoms.
 
Not Mg in my opinion

Not Mg in my opinion

I agree with BurnOne and Dave Coulier this looks like an N deficiency to me.

I'm pretty sure this is what Magnesium deficiency looks like...

https://www.icmag.com/ic/attachment.php?attachmentid=439263&stc=1&d=1513498084

I fixed this with top dress of worm castings mixed with a little dolomite, kelp etc...
The chlorosis was pretty much gone in a week or so. This is also with a fairly large soil volume in a bed albeit inside.
 

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bigjdawg

Member
I'll get some better pics tomorrow. It looks like the classic mag look at first. After adding go calmag to the two plants in the back the problem has seemed to stop so either way I'm not giving them enough nutrients. I added cal mag to all the pots now. It could be nitrogen but I feed them every watering.

2/3 cup Peruvian seabird guano 12-11-2
2/3 cup Indonesian guano 0-7-0
1 cup worm castings
1 cup compost
5 tablespoons molasses
5 tspn maxicrop 0-0-17

Added to 5 gallons ro water bubbled for 24-48 hours. Then given to plants as is with no dilution through entire flower cycle. I did run out of the Peruvian guano and missed two watering with it so maybe that was enough for the plants to suffer.
 

moses wellfleet

Well-known member
Moderator
Veteran
Pests have been ruled out as the cause of the symptoms? Root aphid damage is often only visible during bloom phase, and it is often mistaken for nute deficiencies!
 
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