Calcium deficiency in high pressure aeroponics

Wastei · Jan 23, 2025

Calmag should optimally only be used as a pH buffer in water cultures if needed. You would be surprised how low the requirements for both Ca/Mg are in water cultures and Aeroponics.

There's more than enough Ca in the base formula for running Aero with 3:1 Ca/Mg ratio. You don't want to lower nitrogen even lower and you don't need extra Ca/Mg in Aero. Sensi 3-part is different in composition compared to gh 3 part. Sensi micro only has 2.4% Ca compared to 5.0% in GH's equivalent. Not comparable when doing "Lucas formula".

You don't need to change the mineral ratio much throughout the grow since the requirements doesn't change much. Many people use the same formula from start to finish with stellar results.

If you want to supplement with Ca/Mg it's better to choose a product like Calimagic with very little nitrogen content.

Wastei · Jan 23, 2025

OneHitDone said:
What is the % of hypochlorous acid on the product you are using?

Salt is a no go. I have a Hypochlorous generator and have tried it. You will fry your plants from the excess sodium.
They are recommending Potassium Chloride be used for agricultural applications rather than Sodium Chloride (Table Salt)
I am going to start a post on this topic soon!

The cheapest and easiest route for sterility is using regular unscented bleach(sodium hypochlorite). The Sodium part is minute compared to the hypochlorite side of the molecule and at application rates it's not even detectable. You may even argue that the small amount of sodium better metabolism and uptake of water.

Hypochlorite becomes hypochlorous acid when being dissolved in water. People argue that Calcium hypochlorite is better but it's always more crude in practical use with more sodium chloride than any bleach intended for cleaning floors and surfaces.

I've used it for decades at this point using a dilution calculator like this:
http://foodsafe.ca/dilution-calculator.html

0.5-1ppm is recommended for Aero.

cage · Jan 23, 2025

Wastei said:
The cheapest and easiest route for sterility is using regular unscented bleach(sodium hypochlorite). The Sodium part is minute compared to the hypochlorite side of the molecule and at application rates it's not even detectable. You may even argue that the small amount of sodium better metabolism and uptake of water.

Hypochlorite becomes hypochlorous acid when being dissolved in water. People argue that Calcium hypochlorite is better but it's always more crude in practical use with more sodium chloride than any bleach intended for cleaning floors and surfaces.

I've used it for decades at this point using a dilution calculator like this:
http://foodsafe.ca/dilution-calculator.html

0.5-1ppm is recommended for Aero.

Sodium makes up approximately 30.88% of the mass of sodium hypochlorite (NaOCl).

I think my Calcium hypochlorite is less than 5% sodium.
Was dirt cheap too, made for disinfecting well water.

cage · Jan 23, 2025

endorflight said:
Iam not sure on that. This offends basically what i worked out with @cage, to just increase the calcium. If there is more calcium in the water i guess more will be absorbed at same transpiration levels.

For now i keep running at 5.8-6.2 but ill further investigate what is the ideal range for aero. Sadly there is little info available for HPA overall.

You knocked off one of my horns. I dont want to ruin it by pushing too high. Despite i like extremes so much, i want to be a sucessfully grower the most. I backed down to 750 PPFD and will increase from there again. I will from now on only try to use extreme light levels when i have mastered everything else.

Ill look into that. I didnt expected to deal with the nutrients on such (for me) advanced levels.

The calcium uptake is still parabolic, so you can't keep upping it and expect it to linearly follow.
My main concern was that there was too much potassium that was antagonizing the calcium uptake.

Why Calcium Deficiency Might Start in Lower Leaves

Calcium Mobility and Redistribution:
- Calcium is generally considered immobile in plants, meaning it cannot be easily redistributed from older leaves to newer tissues. This is why symptoms typically show in young leaves or growing tips first.
- However, if the older, larger leaves are affected first, it may indicate:
  - Secondary deficiencies: Competition from excessive potassium, magnesium, or ammonium that inhibits calcium uptake.
  - Localized calcium transport issues: Poor water movement in specific parts of the plant (e.g., due to low transpiration or poor circulation in dense canopies).
  - Physical damage or buildup of stress (e.g., salinity stress) in older leaves that prevents efficient nutrient flow.
Possible Causes:
- Root health issues: Damaged or unhealthy roots may fail to distribute nutrients properly, leading to symptoms in older leaves first.
- Transpiration imbalance: If the growing tips are not actively transpiring (e.g., due to low light or humidity issues), calcium may accumulate elsewhere, resulting in deficiency symptoms in older leaves.
- Nutrient antagonism: Excess potassium (K⁺), magnesium (Mg²⁺), or ammonium (NH₄⁺) can competitively inhibit calcium uptake and result in deficiencies that might first manifest in stressed lower leaves.

Also disregard my idea for dropping the grow, it contains most of the Mg in the program,
though you are using the calmg product.
Yeah dont worry, no need to go so deep, one can manage with much less.

OneHitDone · Jan 23, 2025

Wastei said:
The cheapest and easiest route for sterility is using regular unscented bleach(sodium hypochlorite). The Sodium part is minute compared to the hypochlorite side of the molecule and at application rates it's not even detectable. You may even argue that the small amount of sodium better metabolism and uptake of water.

Hypochlorite becomes hypochlorous acid when being dissolved in water. People argue that Calcium hypochlorite is better but it's always more crude in practical use with more sodium chloride than any bleach intended for cleaning floors and surfaces.

I've used it for decades at this point using a dilution calculator like this:
http://foodsafe.ca/dilution-calculator.html

0.5-1ppm is recommended for Aero.

When running bleach, do you ever check for Free Chlorine in the nutrient solution or just go by a calculated addition?

endorflight · Jan 24, 2025

OneHitDone said:
What is the % of hypochlorous acid on the product you are using?

Looked again, the only info on the bottle is "In 100g are contained 0.1g active chlorine, freed up from hypochlorous acid" (translated).

OneHitDone said:
Salt is a no go. I have a Hypochlorous generator and have tried it. You will fry your plants from the excess sodium.
They are recommending Potassium Chloride be used for agricultural applications rather than Sodium Chloride (Table Salt)
I am going to start a post on this topic soon!

Very interesting topic, im in.

endorflight · 2025-02-21T03:32:51-0700

@Wastei, @cage I hope you are still with me.

What happend the last weeks:
I had dropped the CalMag and did not added mono Cal. The suspected calcium deficiency completely went away. I then had some weeks without any problems. Light intensity now is around 1000 PPFD. 1400 PPFD at the highest most centered tops. 700 PPFD at the lowest most outer tops.

New problems:
This round i had a long veg time to get dailed in first. What turned out as a problem is that the root system is now extremely big and some areas are not beeing fully sprayed anymore. The carpet on the bottom is now 10-15cm high. Due to that some areas started to dry out a bit. Iam not sure how to conclude regarding that. Did i let them too long in veg and they are now too big for my system or did i force them to build a massive root system due to underwatering/underfeeding?

My measurings showed that there was no drain/return back from the water i sprayed. I used that as indicator that they need more. Initially it was around 2L during lights on with 2 sec spray time. Until now i have gradually increased to around 5,5L with 6 sec spray time, which they still seem to use up completely. The nightly consumption is much lower like 1,5L the last days.

Iam now at end of 5th flower week. The strain needs around 10 weeks. I had started to give them PK booster starting with only very little. I then observed new signs on the plants that i mapped to PK deficiencies.
- Slight burn on the edges of leaves and tips. Affected middle and lower leaves
- Purple petioles
- Slightly blueish color on middle and lower leaves

I then increased PK gradually to the full dosage. The last days i started seeing the sides of leaves curling up a little which on the common "defiecienies and excess" chart is a sign of excess of most nutrients. Also i started to see some rust spots on the middle of the leaves again.

I kept the EC at around 1-1.1 all the time. Maybe a mistake lowering all other nutrients too much?

Today i also see that the PH is drifting a bit lower instead of higher. I took root pictures and see some browning that appears to be more than the dry spots now. Could be that i overwatered again (despite they used all the water)? I was leaning more to unterwatering what i though caused the deficiencies. Or did i burn them again, iam almost convinced that in the past it was too high EC causing the browning.

The root zone temps are very stable with 19 degree celsius at day and down to 15 degree celsius at night.

I did a flush today with a higher HOCL dose. Now iam leaning to mix a new rez with reduced PK.

cage · 2025-02-21T06:02:59-0700

endorflight said:
@Wastei, @cage I hope you are still with me.

What happend the last weeks:
I had dropped the CalMag and did not added mono Cal. The suspected calcium deficiency completely went away. I then had some weeks without any problems. Light intensity now is around 1000 PPFD. 1400 PPFD at the highest most centered tops. 700 PPFD at the lowest most outer tops.

New problems:
This round i had a long veg time to get dailed in first. What turned out as a problem is that the root system is now extremely big and some areas are not beeing fully sprayed anymore. The carpet on the bottom is now 10-15cm high. Due to that some areas started to dry out a bit. Iam not sure how to conclude regarding that. Did i let them too long in veg and they are now too big for my system or did i force them to build a massive root system due to underwatering/underfeeding?

My measurings showed that there was no drain/return back from the water i sprayed. I used that as indicator that they need more. Initially it was around 2L during lights on with 2 sec spray time. Until now i have gradually increased to around 5,5L with 6 sec spray time, which they still seem to use up completely. The nightly consumption is much lower like 1,5L the last days.

Iam now at end of 5th flower week. The strain needs around 10 weeks. I had started to give them PK booster starting with only very little. I then observed new signs on the plants that i mapped to PK deficiencies.
- Slight burn on the edges of leaves and tips. Affected middle and lower leaves
- Purple petioles
- Slightly blueish color on middle and lower leaves

I then increased PK gradually to the full dosage. The last days i started seeing the sides of leaves curling up a little which on the common "defiecienies and excess" chart is a sign of excess of most nutrients. Also i started to see some rust spots on the middle of the leaves again.

I kept the EC at around 1-1.1 all the time. Maybe a mistake lowering all other nutrients too much?

Today i also see that the PH is drifting a bit lower instead of higher. I took root pictures and see some browning that appears to be more than the dry spots now. Could be that i overwatered again (despite they used all the water)? I was leaning more to unterwatering what i though caused the deficiencies. Or did i burn them again, iam almost convinced that in the past it was too high EC causing the browning.

The root zone temps are very stable with 19 degree celsius at day and down to 15 degree celsius at night.

I did a flush today with a higher HOCL dose. Now iam leaning to mix a new rez with reduced PK.

Hey, still lurking around.
As mentioned before I don't have experience on the high pressure systems, only in DWC/NFT as for water cultures.
So I'll help where I can.

At 5th week of flower she has demanded some extra P and rest of the way she likes more of a K heavy feed.
She is bit on the bluish color with the petioles being red, without signs of Mg deficiency.
So quite convinced she has lacked some P.

As for leaf margins, the way they are curling up is usually indication of low humidity/too much light.
Little inclined to call start of K deficiency too, considering the P deficiency also.

Few things to consider aswell,
the amount of light is at the very high end, especially without added co2 and maybe not optimal temps/humidities.
I'd say that 1000ppfd is the upper end you'd usually want to go to without extra co2.
Maybe aim for 1000ppfd for the most centered parts and try getting atleast 800 for the rest.
The symptoms could very well be from excess light aswell.

The nightly root temperatures are bit on the low end too.
Usually it's suggested not to go below 18celcius. Below that absorption of P gets a hit (could explain your P deficiency).

Don't focus on maximum light anymore, at this point you'll get the best quality and harvest from not stressing her
rather than trying to maximize light.

*edit As for the roots in general, as long as they stay in good humidity, temps and enough oxygen, they'll do great.
So too thick of a root mat, shouldn't be a problem in itself as long as it won't dry up or run out of oxygen.

Calcium deficiency in high pressure aeroponics

Wastei

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