Ask Lucas

Well I have a PH pen, just no EC or TDS meter yet. I hope to get one soon but I just lost my job friday so the money will be tight for just a little while longer. Here's my setup:

400W HPS, 60-70gallon reservoir. Would your 1/3 addback work for that?? I got somewhere in the neighborhood of an 11% addback. I'm still confused a little on how to do it without a TDS meter. I always used to dump after a week but I really don't want to do that with this huge immobile res. Thanks for any and all help LUCAS.

Hi, I humbly profess I use a $20 TDS meter from ebay, calibration solution, and a reagent ph test kit. I never bought a ph meter, because the reagent worked fine. 2 years ago I bought a qt bottle of reagent, and its still 2/3 full.

I havenet had problem 1 using lucas formula with ro water with those tools.

I have quit doing rez changes as well. I follow the tds found below, as per the plants stage in life.

Indica's
Seedlings and clones 300-400ppm 5.3-5.5 ph
early vegg 500-600ppm 5.3-5.6 ph
middle vegg 600-800ppm 5.4-5.6 ph
late vegg 800-1000ppm 5.5-5.7 ph
early flower 1000-1300ppm 5.5-5.7 ph
middle flower 1400-1600ppm 5.5-5.8 ph
late flower 1000-1100ppm 5.5-5.7 ph
ripening 300-500ppm 5.4-5.6 ph

sativa's
seedlings and clones 250-350ppm 5.3-5.5 ph
early vegg 300-500ppm 5.3-5.6 ph
middle vegg 500-700ppm 5.4-5.6 ph
late vegg 700-900ppm 5.5-5.7 ph
early flower 1000-1100ppm 5.5-5.7 ph
middle flower 1100-1300ppm 5.5-5.8 ph
late flower 800-1000ppm 5.5-5.7 ph
ripening 300-500ppm 5.4-5.6 ph

I simply keep my ph in range and watch my TDS.


Irie

BTW, I got the tables from this thread.

http://www.icmag.com/ic/showthread.php?t=26343&page=1

I'll definitely have to go to EBay then and find one. Thanks for the tip!

agent smith... take a look at my sig block.... ~$30 delivered....

[mace]

Quote:

Indica's
Seedlings and clones 300-400ppm 5.3-5.5 ph
early vegg 500-600ppm 5.3-5.6 ph
middle vegg 600-800ppm 5.4-5.6 ph
late vegg 800-1000ppm 5.5-5.7 ph
early flower 1000-1300ppm 5.5-5.7 ph
middle flower 1400-1600ppm 5.5-5.8 ph
late flower 1000-1100ppm 5.5-5.7 ph
ripening 300-500ppm 5.4-5.6 ph

sativa's
seedlings and clones 250-350ppm 5.3-5.5 ph
early vegg 300-500ppm 5.3-5.6 ph
middle vegg 500-700ppm 5.4-5.6 ph
late vegg 700-900ppm 5.5-5.7 ph
early flower 1000-1100ppm 5.5-5.7 ph
middle flower 1100-1300ppm 5.5-5.8 ph
late flower 800-1000ppm 5.5-5.7 ph
ripening 300-500ppm 5.4-5.6 ph

I simply keep my ph in range and watch my TDS.

Hello I_and_I,

don't take it personally

i've seen this list before (OG) and back then i thought to myself: Thats nonsense, you cannot have a pH of 5.3-5.5 with only 250-350ppm, you would need lots of pH down(which is toxic) to reach that, thats not what makes plants happy.

I still stand on this point of view, this list is nothing but fake, written by someone to have a famous OG FAQ entry, sorry.

peace,

mace

Hi mace, no offense taken........

As i stated above, I maintain my ph within a window, and dont hold it in the small range given in the table. Rather, I test my solution with a reagent kit and hold the ph in a 5-6 window. I use the table mostly as a guideline for maintaining tds, which I can accurately measure with a TDS meter.

You make a very good point about adjusting ph of low tds solutions. It should also be stated, the obvious, that adjusting ph of a low tds solution raises the TDS.

I dont view this list as a definitive guide, but rather a rough outline for solution management.

irie

[mace]

Howdy I_and_I,

this list does not even include the conversion factor of the TDS ppm values, it doesn't say if its .7 or .5, thats a difference of 40% in strength (EC of 2.0mS/cm or an EC of 1.4mS/cm is a huge difference, both are 1000ppm )

Also, nute strength goes with size of lights, stronger lights in good conditions will support more growth, requiring more nutes.

Trust me on this one: Ditch the list You don't need it

[Lucas]

> hydrogen peroxide will kill off the beneficial microorganisms present in Pure Blend Pro and Liquid Karma.

thanks DZ

I stand corrected, PBP contains a bacterial field.. but the gardener does not need to grow the bacteria or do anything at all, to be ready to use the product. Metanaturals otoh, requires the gardener to grow a bacterial field before Metanaturals will function.

so there is a difference between requiring a bacterial field, and simply containing bacteria already.

but my point is actually that PBP works without the user needing to do anything to help grow bacteria


as an aside, peroxide is an oxygen source. bad bacteria would be killed by it, because bad bacteria hate oxygen. Good, or beneficial bacteria, like oxygen, in fact, they require it to survive.

So, anyone needing to use peroxide in their res, has too little oxygen is solution. Peroxide goes away in minutes, so if oxygen is the goal, aereation is the cure, not peroxide.

I respect your opinion that growing bacteria is important for Metanaturals, I disagree that it applies to Pure Blend, but encourage you to post your ideas for the sake of discussion.

one last point, when PBP literature says not to use peroxide, because it kills bacteria that are harmful, that makes no sense to me, but maybe peroxide also kills beneficial bacteria.. I dont know.

Does anyone have information that peroxide kills beneficial bacteria..

in any case, dont use peroxide, its a bandaid for a symptom, whose cause is poor oxygen delivery. Assuming the hydroponic system is properly aereated, the gardener does not need to use peroxide with any nutrients, and need not think about growing a bacterial field, except with Metanaturals.

These comments are specific to liquid nutes used in hydroponics. Im not talking about organic composting, and the role of bacteria in outdoor soil.

Lucas

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[plantbuilder]

stop pretending
you want that job i got ya?
peace.
pb

[Carpet Muncher]

"micro organisms", "to work", "beneficial bacteria"? what <type of> bacteria are we talking about, and what do they actually do? are they symbiotic with the nutes.. in that they're required to work properly? if so, why?

except for "soil", it seems like a sterile system would be simplest, or am i missing something?

[ntstephenson]

I always cringe when a thread gets sidetracked... especially on an issue where two people I respect seem to disagree. Am I suffering from deja vu?

Carpet Muncher- The beauty of Hurtback's recirculating DWC design (and NIMBY's design, and many others) is the fact that supporting healthy bacteria growth is far easier than maintaining a sterile environment. The fact is that there are billions upon billions of bacteria, fungal spores, etc. present in the air. Unless you are growing in a completely sterile environment, they will populate your reservoir. While their benefit may be debated, they are there none the less. It just so happens that the environment your plants need to grow also supports beneficial bacteria (excluding in some instances pH). Personally, I think too much is being made of the issue, unless a bacteria field is required by your nutrients. My experience is, however, quite limited.

Hydrogen peroxide is bad for reservoir management for the same reason that nuclear weapons are bad for warfare. It is at best unnecessary to maintain a sterile reservoir.

KISS

[Lucas]

> Remember that beneficial bacteria will grow in a nutrient system whether you want it to or not (unless you sterilize with Hydrogen Peroxide.)

Sterile nutrients, like GH, dont require bacteria, because the nutes are in plant available form.

Metanaturals nutes are not available to plants until they are further composted by bacteria.

> I think the reason that Metanaturals wants a full colony to work properly is that the ferts it uses require a lot of processing by bacteria to be acceptable by plants.

total agreement, the stuff in metanaturals is not ready for the plants, its ready for further composting

> PBP will still require beneficial bacteria, but not as much as it's likely more processed than metanaturals (which is a good thing.)

bacteria are not required with Pure Blend, it works even if you sterilize

> the environment your plants need to grow also supports beneficial bacteria

good point
the bacteria that are beneficial to the composting process, are oxygen loving

however, there is no requirement to develop a bacterial colony when using nutrients that are already composted


we are discussing several different issues

1. that beneficial bacteria exist naturally in the environment

2. that some nutrients are not available to plants until they have either been refined by man and bottled as plant available water soluble nutrients, or those raw nutrient materials are composted and broken down by bacteria

3. that sterility is undesireable, or unattainable, or irrelevant

imho, oxygen is good for plant roots, and happens to also be good for beneficial bacteria. I agree bacteria will populate a hydro system if they get the right food.. BUT, the beneficial bacteria tend to be involved with the Nitrogen cycle, which REQUIRES manure, or fish poop. Commercial hydro nutes are not usually raw materials that are appropriate food for bacteria involved in the nitrogen cycle that happens in aquariums or soil.

I dont think sterile is the goal, I think healthy is the goal. One way to healthy is to not have bad bacteria. Another way is to have no bacteria at all. Bad bacteria hate oxygen, so the lack of bad bacteria is sterile enough. I dont mind having a few good bacteria around, but since I dont do composting in the reservoir, they are not required.

That is the only point DZ and I disagree on, the question of whether bacteria are Required. I agree they are present, but dont agree they are necessary.

Rather than continue to express opinions and disagreements, I suggest we consider the fact that what most biobucket, active water movement, waterfall based, high water flow rate systems have in common, is that they are good at oxygenating the res. Oxygen is good for roots, its just a coincidence that bacteria like oxygen.

sorry to be so long winded, please see the thread Against BioBuckets to review DZ and my opinions on this topic.

besides opinions, does anyone have evidence to support their opinion? For example, has anyone grown in PBP or GH successfully, without growing bacteria on purpose to make the nutes work. I say, sure, lots of folks.

Lucas

..

[Lucas]

> How would one come up with the optimum temperature, humidity, and CO2 levels for a given strain, growth structure, and watts per sq. foot?

I would begin by making assumptions along these lines...
canopy temp 74F, roots 68, give or take a dose of reality,
humidity 50%
CO2 1000ppm
growth structure if stretchy, provide height, instead of depriving Nitrogen, and use close lighting
watts, 60-75wpsqft, though I often used to read of success at 30-50wpsqft I saw those as more leafy indica yields..

> And what are the more subtle signs that plants need (more or less) humidity, (higher or lower)

high humidity is worse than low, and more common
high, over 80%, is bad cause it decreases water use and growth rate, and causes mold
low, below 40, can increase water use and expose the plants to a stronger res TDS, so lower TDS levels, in the 1000ppm range@.7 conversion, can work

> temperatures, etc. I know the results will show in the yeild, but 2-3 months is a long time to wait to compare results between grows.

high temps, over 85F are very bad, they require the light to be further away than they could be otherwise, decreasing penetration and increasing undesireable leafyness. Indicas with dark wide leaves will suffer bleaching first, some plants will foxtail if bloomed in heat, and especially with hot dark cycles..

I think heat also delays maturity, not sure.

low temps, below 65F in the canopy, will slow growth rate, but actully makes for denser plants with shorter internodes..

as to the wait for yield results disclaimer.. just try not to change too many things at a time..grow, test, repeat..

I suggest we also consider veg time and wattage very seriously

as a basic parameter, I propose a 2 week veg period under T5 fluoros, plus a one week veg period under 1k HPS as a baseline vegetative growth stage lumen input.. a dozen plants per 1k on that lighting program can hit 1.75lbs

the feeding program and root zone technology I currently am interested in is to use veg nutes for veg, on ebb flow in rox, and bloom nutes ebb flowed for bloom.. I think PureBlend is equally capable as GH at KISSing a crop.

those are my guesses DZ, thanks for asking such a direct and useful set of questions.. I hope you and others will contribute your thoughts, as I am by no means an expert

I just belong to a club of very generous human beings who love to share what they have learned through the use of cannabis, and I believe it is a sacrament to be shared, to help heal the wounds of modern civilization..

thanks for being part of my passion for learning, you too plantbuilder

peace
Lucas

[plantbuilder]

lucas how can you say these things?

its pretty easy pb when you have the knowledge base Lucas does.

Seldom have any of my GH res's have been known bacteria farms... only water and nutes. The very few that have headed that way were dumped, the plant roots flushed, res washed out and refilled.

[plantbuilder]

Quote:

It is concluded that local transpiration rate is not the major driving variable for photosynthetic acclimation within the foliage of walnut trees. Photosynthetic acclimation is mainly driven by local light level and light quality... uncoupling local carbon gain and local leaf irradiance still represents a major challenge.

http://jxb.oxfordjournals.org/cgi/co...ll/53/378/2207

..

..

[Lucas]

> evidence of photosynthetic acclimation to elevated carbon dioxide in soybeans results from greater susceptibility to water stress in plants grown at elevated carbon dioxide

translation, if you raise CO2, plants will be unable to use it if the air or roots are too dry.

"On days with either dry soil or dry air, acclimation was apparent. On days shortly after precipitation events and on humid days there was no evidence of acclimation."

http://www.ars.usda.gov/research/pub..._NO_115=112263
---

thanks to plantbuilders acclimation info, it is clear to me that 40% humidity would be overkill.

Thanks to knna's contributions, I take note of the plants Increased need for humidity, as CO2 levels and temperature levels increase.

But look closely at the max humidity levels the Kpa calculators are producing, the max RH is close to 60%, and many grows struggle with numbers that are Way above that, especially in the dark cycle.

So I conclude, Humidity over 60%, or under 50% is going to reduce the maximum ability of the plant to use CO2, even if they get plenty of light.

I agree with DeltaNugz that 1200ppm CO2 and 85F are good max metabolism parameters. And I agree leaf temperatures are key to the game. And I agree VPD in the .9 range, +-.1 is a good target.

To implement these parameters, I would start by controlling for light distance first. Based on lamp size, I target 24" distance from 1k, 20" from 600w, 18" from 400w as rules of thumb.

With the light at that distance, I would then control for leaf temperature at the hottest point on the plant, of no more than 82F.

Then control for room temperature, starting at 75F, no higher than 85F, knowing it may be necessary to run the room lower than 85F, to achieve a limit of 82F leaf temp.

Room temp is not at all the same as the temperature of the air between the lights and the canopy, so I would most definitely not set the AC to 85F.. I like 75F, cause you wont actually get the top canopy down to that temp, since the lights add heat.. hope that makes sense..

As to humidity, given the ability to dehumidify, I would set max humidity to 60%, as knna's info has focused me on that as the max limit, for any temperature, with lower temps, in the 70's actually benefitting from being closer to 50% humidity.. 40% RH is unnecessary overkill

so now our parameters are

CO2 @ 1200ppm
Max Leaf temp for max photosynthesis, 82F
Humidity maximum 60%, minimum 50%
Room temp max 85 (careful with this one, room temp can be cooler than canopy temp, dont let leaf temp go over 82F)

fwiw, if these parameters are not met exactly, it simply means the plant is not growing as fast as it could, but it can still be awesome

Im learning a Lot, thanks again for focusing us on such practical questions DZ, and thanks for the VPD info knna..

Lucas

Glad the VPD info was useful for you. This is the wheel of cultivation: ive learnt a lot from you, and now i can apport something

I agree with Deltanugz, the recomended level of VPD is 0,8-0,95 KPa in veg and early flowering, and raising it (reducing RH) when flower stage go advancing. After the first month in flower, i try to get a 1Kpa level, ive notice it works fine. Probably it cost me some yield, but ive observed that resin production is a lot higher.

Although VPD continue ruling the transpiration rate at night, this rate is far lower that the light transpiration, so i think isnt so important. Better if the VPD range is within the reccomended limits, but i believe it will affect much less the grow rate.

About CO2 at 1200ppm, the RH level to get 0.9-1KPa is over 70%. That is a dangerous level to deal with mold, so a logical conclusion is CO2 enrichment apport little in late flowering stage (2 weeks), because at reasonably RH levels (55%), VPD is outrange, and excess transpiration and probable stomata closure will lead to CO2 unused, without advantages over ambient CO2, or at least over slight CO2 enrichment (500-800ppm).

[herbtastik]

well ive had nothing but GREAT results with 24/7 drip in rock wool.and 2' air stones in 10gal..but i did always wonder if it would be better to have the drip come on and off certain times rather then all day....thoughts on that?

[Lucas]

> the best situation would be a nutrient fog

I agree, and I think that is what is happening in the pore space of any medium based root zone

> how do we control watering frequency so that the roots are in that zone for as often as possible?

the larger the pores, or air spaces in the medium, for example with grorox, the sooner the medium will be dry.

otoh, as long as the medium is not dry, the pores will be full of nutrient fog. The roots will find the fog and thrive.

the denser the medium, for example soil, the smaller the pores, and the fewer fog pores available to the roots. That is one reason there are no roots in the upper half of a pot of soil. Most of the roots are spun around the bottom perimeter of the pot, closest to where fog could form, away from the soil medium itself.

big pores will provide the greatest volume of fog, and will also require more frequent watering. both are a good thing, causing the roots to spend most of their time in fog.

> As long as the root zone is neither dry nor below 5% dissolved oxygen

in medium, there is no way to oxygenate the water if it is sitting there for more than 24 hours. Then we are relying on the pore spaces to provide fog, which will absorb oxygen from atmosphere.

in fact, when relying on pore fog, it matters not what temperature the irrigation is at, nor whether it is oxygenated. The reason is that what makes the roots happy is the fog in the pores. In ebb flow, the heat of the room, and from the lights, causes the pots to warm up nicely, so they produce fog.

> 24/7 drip in rock wool.and 2' air stones in 10gal

I imagine your roots are escaping the soggy rockwool and thriving in the bubbles from the stone. Dry rockwool has pore spaces, wet rockwool does not.

the key to watering enough is to not let the roots dry out.

but the key to not watering too much, is to not let the pores be full of water.

anything inbetween, in terms of moisture levels in the medium, is good, so long as that moisture is feeding the fog into the pores.. so you need pores.. I like grorox on ebb flow as an example of non mechanical oxygen delivery.

Oxygen is delivered in the fog created by evaporation of water in the medium, into the pore spaces in the medium.

Lucas

[herbtastik]

great info lucas thanx again...maybe ill try a new medium...but its hard to teach a old dog new tricks...