Calcium and water hardness

Our water is somewhat hard (TDS of roughly 180 ppm) so I thought that the plants would make use of the calcium and magnesium. However, according to what I've been reading lately, hardness in water is usually from calcium carbonate and magnesium carbonate, which are both molecules that plants can't uptake very well. Some people are saying that these large molecules can actually block the plant's pores and cause lockout.

Any suggestions for dealing with the cal & mag carbonate molecules? I don't want to go RO. Can collect rainwater, but for right now I'm interested in hearing if there are ways of dealing with it. Do AACT brews help combat the carbonate molecules? What about using calcium nitrate?

It should be fine. 180ppm isn't really that high. If calcium carbonate levels in water is too high, nitric acid pH down can be used to make it into more available calcium nitrate form, but that's only if you actually have a problem.

Bacteria in soil break down ammonia into nitrates (NO3-), which will bring Ca slowly into soluble form if you're growing soil.

Sorry, I didn’t explain things very well.

We're newbies. Using FFOF soil. Growing under one LED (A-51 XGS). Some folks believe that LED can exacerbate cal-mag problems.

We have yellowish new growth. As the new leaves grow out they exhibit whitish mottling in the interveinal areas, which often but not always turns into necrotic patches. The problem first appeared right after flushing the plants because it seemed to me that they were suffering from a bit of N toxicity. Shoulda left things alone!

I googled around, looking for solid "plant problem" guides. According to at least one:
Manganese def affects new growth. Leaves yellow at base, necrosis between veins. (That sounds like a match.)
Zinc def is similar to Mn, but leaves twist. (We have a little bit of twisting.)
Calcium def is rarely seen in older leaves, necrosis at the leaf margins. (Doesn't sound like an exact match, but not too far off.)
Sulfur def - pale young leaves, yellowing starts from back of leaf while tip of leaf can look relatively healthy, whole plant as well as new growth. (The "back of leaf" part is a match. The guide said sulfur def is usually pH related. We've been using a dash of AN pH Down to set water at 6 to 6.5 pH. AN uses phosphoric acid, not nitric.)

So here's what we've tried so far:

CALCIUM AND MAGNESIUM I bought some General Organics Cal-Mag+. Because that's what the shop had. A day or two later I realized that the GO Cal-Mag uses calcium carbonate and magnesium carbonate. We already have those molecules in our water, so it seems to me I paid for something I was already getting for free. Probably shoulda shopped for some Cal-Mag that uses different molecules for better absorption. I've used some of the GO Cal-Mag, but concerned that all I'm doing is doubling down with a form of calcium and magnesium that the plants don't like.

I mixed up a mild Epsom salt solution and fed it to the sicker of the two plants.

TRACE MINERALS Bought some ferti-lome Chelated Iron liquid, which contains chelated zinc, manganese, iron, and copper. Adding a tsp per gallon at each watering. Some folks say foliar feed for quick results and to do an end-run around lock-out, but others say they avoid foliar feeding.

PUMP UP THE BIOLOGY We've started brewing AACT. Only two applications so far. It's a very basic EWC/molasses/kelp meal recipe. Small steps Sparky. I'm up for suggestions if someone thinks we should add to that.

The plants look a little better. Not great, but better. I read just this morning that water pH will drop when exposed to air because it absorbs CO2 so I'm setting a pitcher of our well water (meter said 7.5) on the counter today. Maybe I can stop using the AN pH Down solution.

The new RIU format doesn't show links very clearly!

Mellodrama said:

We have yellowish new growth. As the new leaves grow out they exhibit whitish mottling in the interveinal areas, which often but not always turns into necrotic patches.

Click to expand...

This sounds an iron deficiency, which is usually either caused by high pH or too much calcium and magnesium antagonizing iron. (of course I could be wrong)

Mellodrama said:

I've used some of the GO Cal-Mag, but concerned that all I'm doing is doubling down with a form of calcium and magnesium that the plants don't like.

I mixed up a mild Epsom salt solution and fed it to the sicker of the two plants.

Click to expand...

Epsom salts would just make things worse if it's not a magnesium or sulfur deficiency. Like I said above, Mg will just block out other metals, especially Ca and Fe. There should be no problem using calcium carbonate or magnesium carbonate in a soil grow. It's not the forms, it's the elements themselves that you're probably using too much of.

Mellodrama said:

I read just this morning that water pH will drop when exposed to air because it absorbs CO2 so I'm setting a pitcher of our well water (meter said 7.5) on the counter today.

Click to expand...

This matters only for plain water. Once you mix other stuff, the CO2 doesn't really matter anymore. Think of pH buffering like a balance (seesaw). If you put a 500lb weight on each side, adding 1 more lb to a side will not tip the scale, but if you have 0lb on each side and add 1lb to a side, it will tip the scale all the way, even with just 1 pound.

OK, thanks, church -
As you know, and I'm finding out, it's very easy for a newb to careen from one faulty hypothesis to another and keep fixing things until the plant is toast. The interactions that you mention, where too much of one thing inhibits something else, are what scare me. I want it to be A + B =C simple.

I forgot to mention that some of the plant problem guides I read state iron either never, or almost never, causes necrosis. Has that been your experience? I've been thinking that it's a calcium problem based on 1) the comments about LED's and cal-mag problems, and 2) the descriptions of calcium deficiencies that specifically mention necrosis.

I don't yet understand RIU's new format but I'll try to upload a few shots. Under LED color is off a little bit so I held a fluorescent lime green tape measure in one pic to give you some idea of true color. There's a bit of necrosis already showing on a young leaf inside the red circle on the other pic. If they come through that is. I picked off the worst couple of leaves so I couldn't find a good leaf to show the worst of the necrosis. At least you can see the whitish mottling in the interveinal areas and hopefully you can get an idea of the yellowish look to the tops.

Those pictures look a little bit different than I expected. I guess I should have asked first before assuming. It could be that it just needs more nutrients in general, but it doesn't look nearly as bad I read from your description.

I'd still lay off the epsom salts if it hasn't helped already. In that case, it would only make whatever problems you do have worse.

Sorry, I'm used to growing hydroponically. I'm surprised nobody else has posted anything in the nutrients section in days. Maybe try the help section?

Mellodrama said:

OK, thanks, church -
As you know, and I'm finding out, it's very easy for a newb to careen from one faulty hypothesis to another and keep fixing things until the plant is toast. The interactions that you mention, where too much of one thing inhibits something else, are what scare me. I want it to be A + B =C simple.

I forgot to mention that some of the plant problem guides I read state iron either never, or almost never, causes necrosis. Has that been your experience? I've been thinking that it's a calcium problem based on 1) the comments about LED's and cal-mag problems, and 2) the descriptions of calcium deficiencies that specifically mention necrosis.

I don't yet understand RIU's new format but I'll try to upload a few shots. Under LED color is off a little bit so I held a fluorescent lime green tape measure in one pic to give you some idea of true color. There's a bit of necrosis already showing on a young leaf inside the red circle on the other pic. If they come through that is. I picked off the worst couple of leaves so I couldn't find a good leaf to show the worst of the necrosis. At least you can see the whitish mottling in the interveinal areas and hopefully you can get an idea of the yellowish look to the tops.

Click to expand...

Yeah, I noticed it's pretty quiet here but I thought it was the most appropriate place to post. Maybe I should be in the "Plant Problems" sub-forum.

The uglier necrotic leaves were very obvious. I'll try to attach a picture from a week ago.

OK, no more Epsom salts as per your suggestion. I don't think we can hurt anything with the basic AACT brew as described above, do you? From what I've read more organisms in the soil is better than less...

And I think it'd be good to continue with mild applications of the ferti-lome chelated iron/copper/manganese/zinc solution.

I appreciate your input re: our water hardness. I was in the process of convincing myself we had a dire problem.

To me it looks as if it's the start of magnesium deficiency. Judging by those spots, and what I have ran into myself on past grows. Is it on the lower or upper parts of the plants leaves? http://www.growweedeasy.com/manganese-deficiency-cannabis

Mellodrama said:

Yeah, I noticed it's pretty quiet here but I thought it was the most appropriate place to post. Maybe I should be in the "Plant Problems" sub-forum.

The uglier necrotic leaves were very obvious. I'll try to attach a picture from a week ago.

OK, no more Epsom salts as per your suggestion. I don't think we can hurt anything with the basic AACT brew as described above, do you? From what I've read more organisms in the soil is better than less...

And I think it'd be good to continue with mild applications of the ferti-lome chelated iron/copper/manganese/zinc solution.

I appreciate your input re: our water hardness. I was in the process of convincing myself we had a dire problem.

Click to expand...

Well, I was gonna say it starts on the top faces, but after further observation the damage appears to blow right thru the leaf. Back in Post #5 I uploaded a pic with a tiny spot of necrosis. Circled in red. It looks roughly the same on the underside.

I found a leaf that was hiding from me earlier. Pics of top and bottom coming up. Hopefully that's more helpful than the 1st picture..

Another question - could this be light bleaching? Area51 recommends at least 20" distance but there have been several instances where I was closer to 15" or so. I don't think it's light bleaching but my better half thinks it could be.

Dankster, if you happen to see this, what would be the significance of your question about damage to the tops vs. bottoms?

I really appreciate everyone's advice, but too much iron can impede magnesium, right? and vice versa so I don't have a way to proceed.

I didn't know that some of these minerals fight with each other. "It's just a weed" my ass

I'm crossing my fingers that the ferti-lome chelated iron (has iron, copper, manganese, and zinc) might get us back on the tracks. That and all the micro-organisms in the AACT...

My ppm in the tap is 280. Pretty high. Dude at my hydro store told me I dont need to add calcium cause theres enough in the tap. I stopped right when I went into bloom, plants seem fine so far and Im about to harvest. Maybe you could add half the calcium and let the tap do the rest? Im in coco so its different.