Single best ppm for DWC

  • Well, we're still working on things and I imagine we'll see some bugs, some breaking, and things that need to get fixed. We'll start on the most critical things first and work our way down. We're still installing add-on's and squaring away some licensing stuff, but feel free to browse the board and we'll update everyone on when things are added, restored, or otherwise changed.

Simplicio

Auto Warrior
Aug 19, 2017
770
1,497
10
I love the simplicity of Megacrop because the plants need nothing else.
To further simplify things, I'd like to try a grow from unsprouted seed to harvest in a DWC setup without ever changing ppm even once.

The reason for this post is to try to get opinions about what the SINGLE BEST ppm (500 scale) would be, assuming ppm is NEVER changed.

Recently I successfully started unsprouted seeds in Rapid Rooters that were already in a DWC system with max nutes (but not touching sprouts) and max lights, so I don't worry about this single best ppm harming sprouts.
 
  • Like
Reactions: pop22

SmokexBreak

Auto Warrior
Jan 28, 2019
82
142
10
I love the simplicity of Megacrop because the plants need nothing else.
To further simplify things, I'd like to try a grow from unsprouted seed to harvest in a DWC setup without ever changing ppm even once.

The reason for this post is to try to get opinions about what the SINGLE BEST ppm (500 scale) would be, assuming ppm is NEVER changed.

Recently I successfully started unsprouted seeds in Rapid Rooters that were already in a DWC system with max nutes (but not touching sprouts) and max lights, so I don't worry about this single best ppm harming sprouts.
That’s an interesting theory..... I’m actually running my first ever DWC grow. Also using MC. Running photo periods though. Trying to get this DWC down before moving to autos with it.
 

KonopCh

Auto Warrior
Jul 8, 2016
2,284
6,594
20
I would say go with EC 1.0-1.2. I use that in coco DTW, @pop22 is using in autopots I think.

But I think it would be beneficial to tweak some ratios when starting flowering and at the last 3 weeks before harvest. So using some MKP with MC to bump PK and lower N. Then last 3 weeks lower N some more.
 
  • Like
Reactions: Frenjamin Banklin

pop22

Frankensteins Lab Leader
Gladiator Level 2
Dec 15, 2013
15,939
50,161
20
There is no single best ppm. You need to be able to read your plants. That said, a ppm of of 500-535 works very well with many autos. I have a photo period however that peaked on 625 ppms,while another was happy with the 500 range. I recommend starting with 500-535 and let the plants grow for 2-3 weeks. If the plants look a little on the light green color ( and if thats not their genetic color as compared to a breeder photo ) then up your ppm 50-75 ppms.

And I'm using a 700 scale ppm meter. there are conversion factors you can find online.


74
I love the simplicity of Megacrop because the plants need nothing else.
To further simplify things, I'd like to try a grow from unsprouted seed to harvest in a DWC setup without ever changing ppm even once.

The reason for this post is to try to get opinions about what the SINGLE BEST ppm (500 scale) would be, assuming ppm is NEVER changed.

Recently I successfully started unsprouted seeds in Rapid Rooters that were already in a DWC system with max nutes (but not touching sprouts) and max lights, so I don't worry about this single best ppm harming sprouts.
 

Simplicio

Auto Warrior
Aug 19, 2017
770
1,497
10
I would say go with EC 1.0-1.2. I use that in coco DTW, @pop22 is using in autopots I think.

But I think it would be beneficial to tweak some ratios when starting flowering and at the last 3 weeks before harvest. So using some MKP with MC to bump PK and lower N. Then last 3 weeks lower N some more.
That defeats my purpose for using Megacrop, which is simplicity.
I want to test the theory that a single ppm, using MC only from seed to harvest will work.
I already have a little evidence that it will.
There is no single best ppm. You need to be able to read your plants. That said, a ppm of of 500-535 works very well with many autos. I have a photo period however that peaked on 625 ppms,while another was happy with the 500 range. I recommend starting with 500-535 and let the plants grow for 2-3 weeks. If the plants look a little on the light green color ( and if thats not their genetic color as compared to a breeder photo ) then up your ppm 50-75 ppms.

And I'm using a 700 scale ppm meter. there are conversion factors you can find online.


74
I understand that everyone believes there is no single best ppm, but I'm skeptical of whether that's true.
I also understand that everyone believes that we must "read our plants."
But maybe there is a single ppm that eliminates the need to even do that.
I'm willing to risk a grow to find out whether plants can thrive from unplanted seed to harvest using the same ppm always, and for a half dozen different strains.
That implies that the max diet of the finickiest eater must not be exceeded, and the heaviest eaters will have to be happy with that.

For those of us who use the 500 ppm scale,
518 ppm(700) = 370 ppm(500)
625 ppm(700) = 450 ppm (500)

Somewhere between those two values, 370 ppm and 450 ppm, is where I expect the single best ppm to be.
Or maybe I should say the single best ppm that will produce healthier plants than any other single ppm.
 
  • Like
Reactions: Mizzo81 and pop22

KonopCh

Auto Warrior
Jul 8, 2016
2,284
6,594
20
Yea, I know what you want to do.
But anyway, I would stick to 1.0-1.2 EC and in early flowering still using the same EC but less MC and more MKP (it's cheap as plain sugar). Because MC lacks of P in flowering, and also has a little too much N for flowering, thus lowering MC and slightly upping MKP is way to go.

Anyhow, I am here for a ride! :thumbsup:
It is nice test, you should think about EC that don't burn young roots and that the same EC fill pass through preflower stretch when nutes are needed the most. So with autos I will guess that there should be visible signs around 40-50 days. Good luck!
 

pop22

Frankensteins Lab Leader
Gladiator Level 2
Dec 15, 2013
15,939
50,161
20
Without a doubt, plants can survive, even thrive when fed at a specific ppm level. You could feed them at 400 ppms and have a decent grow. Having a great grow requires reading your plants, its not a belief, yo can tell a lot just by looking at, and studying your plants. Plants are living things not machines. They consume nutrients as they need them and what they need. That said, I've completed several grows where my target was 525ppms start to finish. I've seen no need to be exact, the plants don't care 500-540 worked just fine. Most of the time, i hit right on 525.

This plant was fedd at an average of 525ppms
Short Stuff Amnesia CBD


Short Stuff Amnesia CBD pic1 -3-16-2019.jpg
Short Stuff Amnesia CBD pic1 -3-16-2019.jpg




That defeats my purpose for using Megacrop, which is simplicity.
I want to test the theory that a single ppm, using MC only from seed to harvest will work.
I already have a little evidence that it will.


I understand that everyone believes there is no single best ppm, but I'm skeptical of whether that's true.
I also understand that everyone believes that we must "read our plants."
But maybe there is a single ppm that eliminates the need to even do that.
I'm willing to risk a grow to find out whether plants can thrive from unplanted seed to harvest using the same ppm always, and for a half dozen different strains.
That implies that the max diet of the finickiest eater must not be exceeded, and the heaviest eaters will have to be happy with that.

For those of us who use the 500 ppm scale,
518 ppm(700) = 370 ppm(500)
625 ppm(700) = 450 ppm (500)

Somewhere between those two values, 370 ppm and 450 ppm, is where I expect the single best ppm to be.
Or maybe I should say the single best ppm that will produce healthier plants than any other single ppm.
 
  • Like
Reactions: Nosias and Mizzo81

Simplicio

Auto Warrior
Aug 19, 2017
770
1,497
10
Yea, I know what you want to do.
But anyway, I would stick to 1.0-1.2 EC and in early flowering still using the same EC but less MC and more MKP (it's cheap as plain sugar). Because MC lacks of P in flowering, and also has a little too much N for flowering, thus lowering MC and slightly upping MKP is way to go.

Anyhow, I am here for a ride! :thumbsup:
It is nice test, you should think about EC that don't burn young roots and that the same EC fill pass through preflower stretch when nutes are needed the most. So with autos I will guess that there should be visible signs around 40-50 days. Good luck!
As I posted above, I recently planted unsprouted seeds directly into top feed dwc (2 multiple plant reservoirs) with max lights (about 40" away) and max nutes ( EC ~ 0.9).
The plants started slowly because of low res temp (~70 F), but they handled the max nutes and max light very well, and are now thriving.
I did make sure the top feed squirted far from plant stems, and hand watered with distilled and/or 100-200 ppm nutes for a few days to keep Rapid Rooters moist.
This allowed the roots time to acclimate to the max nutes that were wicked up into the hydroton.
The young leaves acclimated to the max light as they were sprouting, and the sprouts didn't stretch, as they had done under less light.

It might be possible to greatly simplify dwc grows by doing several unorthodox things:
1. Plant seeds directly into Rapid Rooters, and immediately put them in a max nutes reservoir, while hand watering for awhile.
2. Use max lights and a single ppm from the time they are planted until harvest.
3. Never ever change out the reservoir unless problems arise.
4. Use multiple-plant reservoirs, and not worry about different nute and light needs.

Adding an external reservoir with float valve can reduce dwc workload to about 0 - 15 minutes average per day, and adds the ability to leave the system alone for a few days.

Preliminary indications are that all of these things do work.
I'm about to start week 10 (or week 7 with the late-planted seeds) with 7 different strains, and haven't ever changed the reservoir at all.
So far, I see no difference between never changing, and changing weekly/biweekly.

The easier growing is, the more people will do it, and dwc can be made very easy.
 
  • Like
Reactions: Mizzo81

Boradan

We don't need no stinking Badges!
Oct 27, 2017
1,924
7,302
30
Currently Smoking
Dinafem Critical+ 2.0, Seedstockers BCN Critical XXL
My last grow was 4 different strains by 4 different breeders all in a 4-pot RDWC system


I used ONLY Megacrop and Remo Magnifical for this grow.
I had 1 plant that was perfectly healthy, 2 that had N-Tox issues and 1 that had calmag deficiency (grown under a single COB).
I find it hard to believe that you could get a 'perfect ppm' for all plants.
Heck, my first grow was 2 Fruit Punch Auto from Heavyweight seeds and one was fine while the other one had N-Tox and calmag deficiency, so it won't even hold true for the same strain.
 
  • Like
Reactions: pop22

Simplicio

Auto Warrior
Aug 19, 2017
770
1,497
10
My last grow was 4 different strains by 4 different breeders all in a 4-pot RDWC system

I used ONLY Megacrop and Remo Magnifical for this grow.
I had 1 plant that was perfectly healthy, 2 that had N-Tox issues and 1 that had calmag deficiency (grown under a single COB).
I find it hard to believe that you could get a 'perfect ppm' for all plants.
Heck, my first grow was 2 Fruit Punch Auto from Heavyweight seeds and one was fine while the other one had N-Tox and calmag deficiency, so it won't even hold true for the same strain.
Your opinion is the accepted wisdom, but I wonder whether it's correct.
It's also accepted wisdom to increase feed until leaf tips start showing orange, then back off.
(A minority of growers probably take the opposite approach, and don't increase feed until leaves look too light green.)

Maybe the "wait for yellow" leads to over-feeding, even after the backoff.
And maybe the plants are getting optimal food long before the yellow happens.
If that's true, then maybe a lower ppm could work for all strains at all life stages. That's certainly what happens with wild plants.
I tentatively believe that this "one size fits all" dwc ppm is somewhere between 300 and 450 on the 500 scale.

The fact that so many people have so many plant issues makes me suspect that over-feeding is the rule, and that many people, especially new growers, could benefit from a single, constant ppm.

I have fallen into the over-feeding trap, even very recently.
It's psychologically difficult to resist the temptation to "feed more to get more."
 
  • Like
Reactions: pop22