LED feed demands

[Broggemann]

f-e, what's your current veg profile?
What ppm of phosphorus are you running?


I'm at 154-72-208-227-87 and while most strains are doing allright, there still seems to be a phosphorus deficiency on some...

 

[FletchF.Fletch]

Hey f-e,

Thanks for this Thread. The challenges of LED feed demands seem like they're compounded by the speed at which the lighting technology develops. As soon as you dial things in, the manufacturers release next gen lights and the learning starts all over again. Really been enjoying this thread, and the idea of mapping out the nutritional needs. Great Work!!

 

[f-e]

f-e, what's your current veg profile?
What ppm of phosphorus are you running?


I'm at 154-72-208-227-87 and while most strains are doing allright, there still seems to be a phosphorus deficiency on some...

I have not spoke about my veg as it's done on very low power. I have the time it takes my plants to flower, to root cuts, veg them and get them in shape to take their place in the flowering area. 10-15w a foot. Placing little demand on them.

174-49-182-192-70

That's just ionic coco grow with nitric and 1ml per liter of 5%-2.5% calmag. Some new seedlings are asking for Mg which is unusual. Though 70 is imo low anyway. It also presumes 0.5% mg in the ionic but actually it's not listed. It's present but no figures. I believe regulation regarding presence state % only need listing if it's over a threshold and traditionally the ionic range shows mg problems. Jacks new cannabis specific grow looks like exactly the same numbers, except they add epsom on top

I do put a bit more P in just before bloom but not a lot. 34ppm taking me to 83. The first week in bloom they just had 270ppm and loved it. I should never of took it back out, but was influenced by stuff I read rather than what I saw. I'm back up to 190ppm and going up again but I lost an important 10 days. My crops screwed.



The signs are just no energy, but out of view there are leaves telling the story too. I had a room fail that stops my progress reports. The weather improved 10c and I didn't knock off a heater. The same weather change bought on the dehu at 430w. I went to trim some fans a week ago and realised I just trimmed my own nails. So onlt got that done yesterday. All in all, a toasty damp canopy (32c74% at peak) so it's not representative any longer.

 

[f-e]

Oh.. I worked out my veg as you asked, but upon mixing a bucket I found myself reaching for the P. Taking me to ~80ppm but I don't always.

Other opinions range from 60 to 90 with similar Mg heading towards the ramp up for 12/12



I bumped my PK to 230-300 and have seen a positive response. Early days though.
Interestingly Ionic bloom+boost is 100-233-347 which was always too rich and burnt them under sodium.

 

[ButterflyEffect]

I have not spoke about my veg as it's done on very low power. I have the time it takes my plants to flower, to root cuts, veg them and get them in shape to take their place in the flowering area. 10-15w a foot. Placing little demand on them.

174-49-182-192-70

That's just ionic coco grow with nitric and 1ml per liter of 5%-2.5% calmag. Some new seedlings are asking for Mg which is unusual. Though 70 is imo low anyway. It also presumes 0.5% mg in the ionic but actually it's not listed. It's present but no figures. I believe regulation regarding presence state % only need listing if it's over a threshold and traditionally the ionic range shows mg problems. Jacks new cannabis specific grow looks like exactly the same numbers, except they add epsom on top

I do put a bit more P in just before bloom but not a lot. 34ppm taking me to 83. The first week in bloom they just had 270ppm and loved it. I should never of took it back out, but was influenced by stuff I read rather than what I saw. I'm back up to 190ppm and going up again but I lost an important 10 days. My crops screwed.

[URL=https://www.icmag.com/ic/picture.php?albumid=85599&pictureid=2124244&thumb=1]View Image[/url]

The signs are just no energy, but out of view there are leaves telling the story too. I had a room fail that stops my progress reports. The weather improved 10c and I didn't knock off a heater. The same weather change bought on the dehu at 430w. I went to trim some fans a week ago and realised I just trimmed my own nails. So onlt got that done yesterday. All in all, a toasty damp canopy (32c74% at peak) so it's not representative any longer.

Are you saying you have 270ppm of P? You're in coco, right?

 

[f-e]

First 2 weeks of 12/12 I did yes. They loved it. It's not as high as Jacks cannabis feed by a long way, but a bit over Growth Technologies numbers for the last half of flowering.


Edit: I should add, Jacks are heading for 400 iirc but only for 2 weeks. It's used on top of their grow feed. Which they continue with to about week 5. I had to stop before week 3 as the N was too high

 

[ButterflyEffect]

First 2 weeks of 12/12 I did yes. They loved it. It's not as high as Jacks cannabis feed by a long way, but a bit over Growth Technologies numbers for the last half of flowering.


Edit: I should add, Jacks are heading for 400 iirc but only for 2 weeks. It's used on top of their grow feed. Which they continue with to about week 5. I had to stop before week 3 as the N was too high

Maybe I'm confused. How do you get your P numbers so high? You sure you don't mean K? Even when I'm pushing a gram a gallon of MKP on top of jacks 321, I don't go over 100ppm of P.

Although I have started to add a bit of MKP from transition thru stretch to ramp up the P for flower.

 

[f-e]

A gram of mkp is about 130?

https://www.rapidtables.com/convert/chemistry/ppm-to-mg-per-liter.html


Talk about leaving things on a cliff hanger. It's gonna be 4 days before we see who's math's crap lol

 

[eyesdownchronic]

A gram of mkp is about 130?

https://www.rapidtables.com/convert/chemistry/ppm-to-mg-per-liter.html


Talk about leaving things on a cliff hanger. It's gonna be 4 days before we see who's math's crap lol

i think youre forgetting to adjust by .46 for P205 to P.
a gram of MKP is like 60 ppm of P.

N is already in elemental form so you dont need to adjust.

P is .46 of P2O5

K is .83 of K20

 

[f-e]

Yes, I have been reworking my figures in my 3 days off. I'm going to go back over some old posts here to put notes in, and move to elemental figures. I have never understood why we state Oxide amounts on feeds when they are not oxides, so I'm happy to move away from that. Now if only zero degree's wasn't when the oceans freeze over and 100 the best you can get under your armpit. The whole world could work together

I have actually settled around (where is that pizza box lid) 114-102-204-145-60 now. Though I have to guess my tap. That's elemental

I can't raise the K as it burns my Kush based plants. I saw a Kush leaf analysis where everything was fair except it had double the K present than was thought reasonable. For a while I have been unable to bump the K because of one Kush in particular. My main strain. So I think my K issues are more related to Kush genetics than LED's.

 

[Fitzera]

Yes, I have been reworking my figures in my 3 days off. I'm going to go back over some old posts here to put notes in, and move to elemental figures. I have never understood why we state Oxide amounts on feeds when they are not oxides, so I'm happy to move away from that. Now if only zero degree's wasn't when the oceans freeze over and 100 the best you can get under your armpit. The whole world could work together

I have actually settled around (where is that pizza box lid) 114-102-204-145-60 now. Though I have to guess my tap. That's elemental

I can't raise the K as it burns my Kush based plants. I saw a Kush leaf analysis where everything was fair except it had double the K present than was thought reasonable. For a while I have been unable to bump the K because of one Kush in particular. My main strain. So I think my K issues are more related to Kush genetics than LED's.

If you have a water shop in your area, they might be able to help you out with knowing what's in the tap water before filtration. Maybe. Some only check after they've filtered it but some will know the input. Same with aquarium stores, they might be able to give you an idea.

 

[ButterflyEffect]

Yes, I have been reworking my figures in my 3 days off. I'm going to go back over some old posts here to put notes in, and move to elemental figures. I have never understood why we state Oxide amounts on feeds when they are not oxides, so I'm happy to move away from that. Now if only zero degree's wasn't when the oceans freeze over and 100 the best you can get under your armpit. The whole world could work together

I have actually settled around (where is that pizza box lid) 114-102-204-145-60 now. Though I have to guess my tap. That's elemental

I can't raise the K as it burns my Kush based plants. I saw a Kush leaf analysis where everything was fair except it had double the K present than was thought reasonable. For a while I have been unable to bump the K because of one Kush in particular. My main strain. So I think my K issues are more related to Kush genetics than LED's.

Now I get it! You're not from the US. We do things weird here.

I'm interested in this as I'm running into constant P issues during stretch. I know my runoff is around 6.5, which is allegedly outside of the range for P, but then I read that I shouldn't be concerned about hempy runoff. I really think that I do need to worry.

What do you do to enhance P? Foliar? I have MKP and I just picked up MonoPotassium Sulfate and Potassium Sulfate.

 

[f-e]

Now I get it! You're not from the US. We do things weird here.

I'm interested in this as I'm running into constant P issues during stretch. I know my runoff is around 6.5, which is allegedly outside of the range for P, but then I read that I shouldn't be concerned about hempy runoff. I really think that I do need to worry.

What do you do to enhance P? Foliar? I have MKP and I just picked up MonoPotassium Sulfate and Potassium Sulfate.

In the UK we use oxide numbers for many of the ingredients, while I think in the US you state P&K as oxide, though that's just label stuff. I think for ppm we should leave the old ways behind and just go with elemental. I think most people do this already but having only just started watching the numbers I had not realised this. It's bad science talking oxide when it's not even there and just gives numbers to convert back again. I'm calling it my biggest goof of the last year.

I don't think we can ever ignore runoff as an indicator of root pH. The reading might need some thought, but is certainly worth something.

During stretch, work has been done with P to effect plants morphology. Keeping it down to just 20ppm has reduced stretch 15% without effecting the onset of buds. Myself, I thought 20ppm would be a nightmare. It hard to go so low without mixing your own feeds. As they pointed out. Confirming they really mean it.

P for me can happen during stretch due to cold nights. If you have hot night, even hotter than days, stretch is reduced. Perhaps lowering P demand. Making it a two pronged strategy.
I have an electric blanket hidden under everything to combat this P issue in particular.

Oh... it is 6 week photo day... dunno if I should embarrass myself

 

[f-e]

Week ending 6 weeks was not bad for progress. The idea of 100-100-200-140-80 is about where I have ended up. It's not been a perfect week, but as a stand alone 7 days not bad imo.

 

[ButterflyEffect]

In the UK we use oxide numbers for many of the ingredients, while I think in the US you state P&K as oxide, though that's just label stuff. I think for ppm we should leave the old ways behind and just go with elemental. I think most people do this already but having only just started watching the numbers I had not realised this. It's bad science talking oxide when it's not even there and just gives numbers to convert back again. I'm calling it my biggest goof of the last year.

I don't think we can ever ignore runoff as an indicator of root pH. The reading might need some thought, but is certainly worth something.

During stretch, work has been done with P to effect plants morphology. Keeping it down to just 20ppm has reduced stretch 15% without effecting the onset of buds. Myself, I thought 20ppm would be a nightmare. It hard to go so low without mixing your own feeds. As they pointed out. Confirming they really mean it.

P for me can happen during stretch due to cold nights. If you have hot night, even hotter than days, stretch is reduced. Perhaps lowering P demand. Making it a two pronged strategy.
I have an electric blanket hidden under everything to combat this P issue in particular.

Oh... it is 6 week photo day... dunno if I should embarrass myself

For sure, I've gotten confused trying to parse info about good ratios to use. For example, I've seen the 3:1:4 ratio for NPK and that one was expressed elementally, but the Ca:K:Mg ratios I saw were all done with oxide. It took long nights of studying to figure that out!

If you can go that low on P during transition and not see a def then I'm pretty certain I'm getting lockout due to pH. Best I can tell right now is that I'm using a 4:1 Perlite:Vermiculite and my N is entirely Nitrate-based. Further compounding the issue is my overfeeding. I've moved to feed at lights on and water 3 hours before lights off to give the media a good flush. So far so good on the runoff EC, but the pH still isn't coming down. Next, I'll add a pinch of MAP and see what happens. Fortunately, I don't have to worry about temps as I have room heaters that keep the nighttime temps a little below the day.

I see nothing in those pics to be embarrassed about! They look great!

 

[f-e]

Perhaps your P problem is in the 3 hours before bed and through the night. I'm not sure what you mean by watering them daily to flush, but it's a point of interest. I imagine the root system big enough to find food when fed, might not be big enough to find food in just water. While one big enough to find food it just water, might not like being fed. I would of thought this stressful for the plant. Could you mix the two buckets together and just give them that twice a day? Then if the run-off starts to leave the chart, put an extra feed through them about 20 minutes after a normal one. No plain water ever. That's for soil. Just another feed to replace the one that's there. Having given 20 mins for the salts to get dissolved as best as can be. My watering cycle is 9 mins, but is actually 5 on for near saturation, 10off, 4 on which is mostly causing run-off . Which gets a lot more out than 9 minutes straight. I do have quite a high runoff percentage but it's what keeps the root EC down, and refreshed. Though I'm aware K is a lot more soluble than Mg or Ca, though nothing like as soluble as N (on the whole). I'm not sure about P. I'm forever learning to.

My pic looks healthy at a glance and if they were long flowering plants okay. However this is them at 6 weeks during another run (I was unhappy with)


I held N too high going into week 3 at about 165ppm. While I pushed the stretch and stature of them with P until that time, then lowered it way too much. Though still more than I would of used under sodium, by quite a margin. In line with my extra ppfd looking back. I need to really comb through my logs still, but this grow is over for me. Test done. I failed Which is the whole point of a test grow

 

[GoatCheese]

I don’t think cannabis needs any stronger NPK nutrients under modern ”white” leds, just something extra that keeps the leaves from dehydrating/frying.

I have a small auto-plant in coco in my veg cab and it looks much better than the plants in potting soil with same BioBizz nutrients; imo, it looks better cause there’s more water in the plant’s system and the leaves won’t fry/dehydrate so easily. But I don’t think the plants need more Nitrogen because of modern leds as some growers seem to think = they seem to think the yellowing from the leaves dehydrating is Nitrogen deficiency but it is not, it’s the leds frying the leaves cause the light is too close to the canopy or the led is running with too much watts.

Along the basic BioBizz Grow and Bloom I give them 0,5ml/L Canna CalMag (same for soil and coco plants) and the auto in coco crows just normally.

So I don’t think there’s much need to adjust the NPK nutrients under white leds, just try to give them nice RH% and abit of CalMag to help to keep the leaves in better shape.

What is important is that you have enough clearance between the canopy and the light. In my bloom tent I have about 65-70cm between my Cree COBs and the canopy and I can’t run my three COBs even at 30 watts/each or the leaves will start suffering abit too much (plants in soil), cause the winter air up here in the North is so dry, but I’m sure that in the summer I can go abit past the 30 watts each @ 65-70cm between the COBs and the canopy cause there is more humidity in the air.

 

[f-e]

Interesting viewpoint GoatCheese. Perhaps more relevant to your grow than others though, as it's not an idea aired before.

I found N use increased when I first went to LED, but decreased over the years. It's still a bit higher but the N in calmag covers it. Calmag being something I must start off with now, but not with HID. Many found a Ca problem from lower temps reducing transpiration. Well.. many is a bit of an understatement. Most now lean on a bit on calmag for support so get extra N without much choice so isolating the need for more is a little difficult. As they put more in regardless. I don't see N deficiencies from low lights drying plants, I see the age old sings of excess N when baking a plant so hard it can't actually use it.

Perhaps setting 30w so high up isn't taking advantage of the extra grow potential of LED, so you don't need the extra feed. I veg at under 15w a foot and can get away with just a little extra mag at under 10w, which I always needed but could ignore with HID, having learned to just reduce the illumination level to get past it. That's the balance right there. Under hid I had the Mg issue that just slowed my veg a little. With LED I'm wasting my light just matching that growth. I could, but would rather make use of the extra ppfd I can create, which means I must correct that Mg. Then the other things that follow as I push harder. Standard stuff really. Don't push a plant and it will find what it needs in almost any feed.

What area is your 30w covering? Perhaps we can help you speed things up a bit. At the start of this thread many reported just 40% more food worked. We knew at the time it wasn't going to be everything required at 40% higher so that's really where I have been picked away at things. The N because we want to grow more. The P to harvest the light. The Ca if you run cooler. The Mg for the extra photosynthesis. It seems K and Fe are not showing, and the rest of the low level stuff. So it boils down to P to harvest the light, then Mg and N so you can use it. Or so it seems to me. I have only been looking at this a short time though. So I'm certainly listening to what you say and finding it influential. You are an outlier though. As am I with my rejection of K boosters. We might be wrong, but it's working, which counts.

 

[GoatCheese]

Interesting viewpoint GoatCheese. Perhaps more relevant to your grow than others though, as it's not an idea aired before.

I found N use increased when I first went to LED, but decreased over the years. It's still a bit higher but the N in calmag covers it. Calmag being something I must start off with now, but not with HID. Many found a Ca problem from lower temps reducing transpiration. Well.. many is a bit of an understatement. Most now lean on a bit on calmag for support so get extra N without much choice so isolating the need for more is a little difficult. As they put more in regardless. I don't see N deficiencies from low lights drying plants, I see the age old sings of excess N when baking a plant so hard it can't actually use it.

Perhaps setting 30w so high up isn't taking advantage of the extra grow potential of LED, so you don't need the extra feed. I veg at under 15w a foot and can get away with just a little extra mag at under 10w, which I always needed but could ignore with HID, having learned to just reduce the illumination level to get past it. That's the balance right there. Under hid I had the Mg issue that just slowed my veg a little. With LED I'm wasting my light just matching that growth. I could, but would rather make use of the extra ppfd I can create, which means I must correct that Mg. Then the other things that follow as I push harder. Standard stuff really. Don't push a plant and it will find what it needs in almost any feed.

What area is your 30w covering? Perhaps we can help you speed things up a bit. At the start of this thread many reported just 40% more food worked. We knew at the time it wasn't going to be everything required at 40% higher so that's really where I have been picked away at things. The N because we want to grow more. The P to harvest the light. The Ca if you run cooler. The Mg for the extra photosynthesis. It seems K and Fe are not showing, and the rest of the low level stuff. So it boils down to P to harvest the light, then Mg and N so you can use it. Or so it seems to me. I have only been looking at this a short time though. So I'm certainly listening to what you say and finding it influential. You are an outlier though. As am I with my rejection of K boosters. We might be wrong, but it's working, which counts.

No it’s not only 30 watts, it’s three (DB bin) Cree CBX3590 x 30 w = 90 watts, now at about 85 watts all together
My bloom tent is 50cm x 90 x 160 and I can’t raise the light fixture any higher.

In my veg cab (50x80x140cm) I have one of those Crees running around 21-23 watts with a 10 watt led flood light on the side to give some angular light. plants are about 60 cm from canopy

I’m in a bit of a hurry and I have to come back and read your post better later.

 

[Koondense]

I have similar experience, during winter low temps and humidity require a different lightning approach comparex to summer grows, lots of earlier def showing and higher temps helping with photosynthesys at high light levels. Winter grows could go with 60% of light compared to summer but in this case some extra heating will be needed. I move my led drivers in and out of the growspace, otherwise the yields will suffer drastically. Resin coverage not so but mass will be a half of the summer mass.
Thinking of a hid light for winter...

Cheers