Calcium deficiency won't go away?

Hi all, I'm in the middle of my first grow, and like many others, I thought I had it all figured out, but can't seem to get to the bottom of one problem ...

I have what appears to be a calcium deficiency, but it won't seem to go away, regardless of what I try to do.

Here's what my setup looks like:

Strain: Autoflower Blue Mystic
Grow Medium: Hydroponic (Top-fed DWC)
Number of Plants: 1
Size of grow space: 3' W x 1.5' D x 5' H
Age of plant: About 7 weeks; preflowers first appeared about 2 weeks ago
Lights: 1x Galaxyhydro 300W LED Panel on top, 4x 32W T8 lights for side lighting
Light cycle: 20/4
Light-to-canopy distance: 20"
Canopy temp: 79-83 degrees with lights on, 68-70 degrees with lights off
Reservoir temp: 68-72 degrees, cooled with a homemade TEC chiller
Reservoir size: 5 gal bucket
Reservoir PH: Currently 6.2, it has varied from 5.8 to 6.4
Water Source: RO Water
Ventilation: 190CFM Duct fan with carbon filter
Humidity: Currently 35% (lights on) to 45% (lights off). During veg, was kept at 70% with a humidifier.
DWC Bubbler: 125GPH air pump w/ 2 large airstones
Reservoir change interval: Weekly
Nutrients:
- GH Flora Series (Gro, Bloom, Micro)
- GH Floralicious
- GH Liquid KoolBloom (Started adding last week)
- GH FloraNectar (Started adding last week)
- GH CALiMAGic
- GH RapidStart
- Hydroguard
All nutrients have been ramping up from 1/4 the recommended dose on the bottle, currently at 2/3 strength. Exceptions are hydroguard (using at full strength) and CALiMAGic (see below).

The problem:

I began to see signs of a calcium deficiency (brown necrotic spots speckled randomly on leaves) immediately after I switched from tap water to RO water (about 4 weeks ago). I quickly realized my mistake and, 4 days after switching to RO water, I started adding GH CALiMAGic according to the directions on the bottle (1tsp/gal, before adding other nutes). Since then, the problem has persisted, with some leaves much worse than others. I've been steadily increasing the concentration of CALiMAGic to try to compensate. I'm currently up to 2tsp/gal (double the recommended dose). I'm not currently seeing any signs of other nutrient lockout, but I'm afraid to go higher. I've also been feeding it a weak CALiMAGic solution via foliar spray.

Affected leaves start out with small brown spots randomly appearing on the leaves. These multiply over time, and eventually consume most of the leaf. Leaves otherwise stay green until the brown spots take over about 50% of the leaf, at which point they start turning yellow. Some of the early leaves affected by this appear completely dead, but are not falling off the plant. Almost every leaf on the plant is affected to some degree, but some are much worse than others.

Additional history:

This plant had a bit of a hard time in its early life. It was sprouted in a failed hydroponic space bucket experiment, and was rapidly (about 1 week after sprouting) moved to its current growing space (it was still a seedling at the time). Over the next 2 weeks, I dealt with several miscellaneous rookie problems including lack of dissolved oxygen (too small of an air pump initially), too high reservoir temperature, and very mild nitrogen toxicity. During that period its growth seemed stunted. However, for the last 4 weeks, all of the environmental problems have been solved, and it has been growing rapidly - the only remaining issue is the (apparent) calcium deficiency, which is persistently appearing on new growth.

Since it started growing rapidly, it has been growing very significantly side-to-side, and is very bushy, but not terribly tall (plenty of growth nodes, but not much space between them). This is probably a consequence of the significant side lighting and relatively short night cycle.

Questions/theories:

My first question is, is this indeed a calcium deficiency? It initially started when I started using RO water, and it has all the signs, but after its resistance to CALiMAGic, I can't be sure. I don't believe it's a PH problem (the PH has been regulated between about 5.8 to 6.4 for the plant's life, recently I've been keeping it above 6.0 because I read that calcium is absorbed better). I also don't think it's a root problem, because the roots look healthy, and the reservoir still smells fresh and clean. I haven't noted any signs of pests (I've checked for spider mites, which can apparently cause similar issues) or fungus.

If it is a calcium deficiency, is it possible that it's the result of a nutrient lockout? I'm not feeding excessive amounts of nutrients, except possibly for CALiMAGic, which I started after the problem appeared. Is it possible that too much CALiMAGic can lock itself out? I don't see any other signs of nutrient deficiencies, even though this problem has been around a while.

Is it at all possible that it still, even after feeding 2x the recommended dose of CALiMAGic (for RO water), doesn't have enough calcium? Is it even safe to feed it more? My RO water is made from a 5-stage filter that produces very pure water (PPM 0, with a PH of exactly 7.0) - could it have even less calcium than the RO water CALiMAGic was designed for?

Pictures are attached. Leaves pictured are different leaves in different stages of the problem.

Any help is greatly appreciated!

it dosent look like cal but pics under a reg light might help

Oops, forgot that LED lights also have a weird color spectrum ...

Here are 3 pictures (under just fluoros) of leaves in 3 stages. The first one's a bit blurry, but shows only a few spots on a relatively new leaf. The next two are older leaves that have progressed.

definitely looks like calcium IMO. when you say it "won't go away"... are you referring to the leaves that it has already affected, or it keeps showing up on new leaves that were showing no symptoms before? once that damage occurs, it will never go away, but it should stop spreading when it gets put under control.

another way to look at this issue is.... could calcium ions be getting substituted for other competing ions like K+, Na+, and Mg 2+??? Sometimes an excess of these competing ions can cause a lower intake of Ca 2+.

water stress and root stress can greatly affect uptake of Ca as well....

It's consistently showing up on new growth. I've been treating the problem with CALiMAGic for about 4 weeks now (started at the recommended dose on the bottle and been going upward from there), with new sets of leave appearing every few days, and still each new set of leaves has this brown spotting to some degree. Also, already affected leaves tend to get worse.

If the calcium is indeed being out-competed by other ions, how would I go about determining or fixing that? I'm only using 2/3 the full dose of the other nutrients, but am now up to double the dose of CALiMAGic. Would I possibly need to flush the reservoir with something like flora kleen?

I don't think the roots are having any issues ... they look healthy to me (a nice beige/white color), and the water is clean (clear except for the slight tint of dyes from nutrients) and smells fine. The PH of the water is around 6.0 and varies slowly from 5.8 to 6.4, and the water temp never goes above 72 degrees. Is there another form of water stress or root stress that I'm missing?

At this point, I'm not sure if I should just keep feeding it more CALiMAGic and risk some other nutrient lockout, or if I should attempt to do a full flush of the reservoir with something like flora kleen for a few hours and go back to the bottle-recommended dose of CALiMAGic; or do something else entirely.

Try Epsom salts
I believe the recipe is 2 tbs to a gallon of water. Three watering if needed. Mine cleared up once at 1 watering once at 2

Aren't epsom salts for magnesium deficiency, not calcium deficiency?

I think you are running your pH too high. Being hydro, your pH should never (EVER) be above 5.8 and it should be closer to 5.6 normally. You probably have multiple deficiencies going on. The rust spots indicate a Mg deficiency, not Ca. When you use r.o. water, you should always include an additional 5ml per gallon of cal/mag (above what you were normally giving the plants) to make up what the r.o. takes out. As a first step, I'd consider a foliar spray with a deluted cal/mag mix. Keep your pH low and things should return to normal in your new growth.

Adjust your PH. this is what causes that leaf issue. Fluctuations causes the spotting.

I would go for 6.5 - 6.8. I had to raise PH to get the symptom to stop. Leaves that are affected will not come back.

I grow in soil and PH petered out in medium ( runoff hit 5.5 ) so I upped it with dolomite lime and calimag foliar spray. It stopped it from progressing.

I've tried raising the PH a bit. From what I've read, the PH in hydro should be kept between 5.5 and 6.5, but calcium and magnesium are best absorbed above 6.2. The GH nutes are buffered much closer to 5.5, so I've been adding PH up to get the PH around 6.0-6.5 . Is it possible that these PH fluctuations alone (even though the PH is always in that 5.5 to 6.5 range) could be causing the issue?

I can try changing out the reservoir and leaving the nutrient solution much closer to its naturally buffered 5.5-5.8, but I'm a bit worried that this could cause additional problems relating to PH fluctuations.

When you use r.o. water, you should always include an additional 5ml per gallon of cal/mag (above what you were normally giving the plants) to make up what the r.o. takes out

Click to expand...

I'm currently adding 10ml/gal total. I'm not sure what is "normal" for the plants because this is my first grow. How much above the 5ml/gal mark is it safe to give the plants? I'm using CALiMAGic instead of CalMag because of the lower nitrogen content.

jiffyluke said:

I've tried raising the PH a bit. From what I've read, the PH in hydro should be kept between 5.5 and 6.5, but calcium and magnesium are best absorbed above 6.2. The GH nutes are buffered much closer to 5.5, so I've been adding PH up to get the PH around 6.0-6.5 . Is it possible that these PH fluctuations alone (even though the PH is always in that 5.5 to 6.5 range) could be causing the issue?

I can try changing out the reservoir and leaving the nutrient solution much closer to its naturally buffered 5.5-5.8, but I'm a bit worried that this could cause additional problems relating to PH fluctuations.



I'm currently adding 10ml/gal total. I'm not sure what is "normal" for the plants because this is my first grow. How much above the 5ml/gal mark is it safe to give the plants? I'm using CALiMAGic instead of CalMag because of the lower nitrogen content.

Click to expand...

I think 10ml/gal is waaaaay too much. You might actually be locking out the Ca now, from using soo much of the calmag. If using Ro water in most hydroponic setups, I'm usually using around 2.5-3ml/gal of calmag before adding base nutes. Sometimes a little more if in coco. I always ph to 5.8-6.0. Works great everytime. ALWAYS has.

I would tune down your nute soup a bit, until at least you get this problem figured out. For now: ditch the liquid koolbloom and the floranectar. Hell, I wouldn't even use the floarlicious in a dwc setup either! That stuff smells like stale, dirty diapers and in my opinion, totally unnecessary, just like those other two I recommend you drop. Keep It Simple Stupid

hard to tell but in the pic of your roots, they look slimy. are they nice and white or brown and slimy?

since you already have the GH stuff, i'd use Lucas formula with your RO. 8ml micro/16 ml bloom per gallon. no need for cal/mg either. and your pH will settle right around 5.8 too.

jiffyluke said:

Aren't epsom salts for magnesium deficiency, not calcium deficiency?

Click to expand...

Yes. Epsom salt is magnesium sulfate.

In soil, 6.3-6.5 is appropriate then. Never go above 6.5 as things begin to lock out then. 10ml per gallon of cal/mag with r.o. water is perfectly acceptable

SSHZ said:

In soil, 6.3-6.5 is appropriate then. Never go above 6.5 as things begin to lock out then. 10ml per gallon of cal/mag with r.o. water is perfectly acceptable

Click to expand...

the OP is in DWC not soil. pH should be 5.5 to 6.1 in hydro.

5ml/gal is correct dosage for calimagic with RO.

I use Botanicare Cal/Mag and 10ml/gallon is the correct dosage with R.O.

OP uses calimagic by general hydroponics. says 5ml/gal right on the bottle.

I don't get it. I've been doing this for quite sometime. I've never needed 10ml/gal of calmag. That amount of cal-mag+ has an EC of roughly 1.1+. Calimagic would be similar.
To me that's crazy. I hardly ever even use 5ml/gal, and When I do, it's just occasionally in my coco grows with RO.

Aeroknow said:

I don't get it. I've been doing this for quite sometime. I've never needed 10ml/gal of calmag. That amount of cal-mag+ has an EC of roughly 1.1+. Calimagic would be similar.
To me that's crazy. I hardly ever even use 5ml/gal, and When I do, it's just occasionally in my coco grows with RO.

Click to expand...

i use Lucas formula with RO. never need cal/mg either. i suggested that in an earlier post