The Chemistry behind Coco Coir: a (strange) journey from ferts bottle to to buds

[blueberrydrumz]

Just to be clear....I understand I should not be adjusting my pH based upon runoff, but are you also saying a nutrient solution pH of 7 is nominal? Please advise kind sir.

hey paperchaser..
cook will be able to explain better, but
i think you missunderstood,
RO water has a ph of 7 and so the cations and anions are in equilibrium
optimum ph range for coco is 5.5 - 6, so feed accordingly.
You have to find out via a slury test what ph your media has and then adjust your feed accordingly, but most of the time you will find rez ph to be between 5.5 -5.8 depending on flowring stage as well.
flowering beginning around 5.8 - 6
flowering ripening around 5.4 - 5.8
hope that helps

 

[Dready_jake]

sorry. To be clear.

rather than the once daily, I did a test where I split the nute solution and watered twice, measuring the runoff from the second watering to the input.

I typically see 200+ higher, this time it was only 100 higher, and so closer to the input solution.

So as was hypothesized it was not the lack of runoff volume I got, but a lack og watering frequency that lead to evap in the coco and resulting increase in ppm. Thus at the next water I would see the higher ppms on the runoff.

Honestly my plants are too big for these containers and even 2x a day is not enough. Hence I am going to try the blumat approach. I like the idea and am so cramped for space bigger pots are hard to work in.

Regards

But that's the point. If your only getting up to two times a day then you're not yet unlocking the hydroponic miracle that is coco. Keep that root space and slowly up the waterings per day til you get to like 6-10! But don't rush it cuz I might have on my smaller plants. They weren't Keeping up with this bigger plants and I maybe jumped from 2 to 3 waterings too quickly. if you're in your final pot 3-4 waterings a day is the perfect time to flower IMO cuz then as they flower they'll get up to the 5 and maybe even 6 times a day and youll get to watch them swell.

I'd love to hear your opinion on these word cook! Correct me for the sake of everyone's learning

 

[The.Cook]

Honestly my plants are too big for these containers and even 2x a day is not enough. Hence I am going to try the blumat approach. I like the idea and am so cramped for space bigger pots are hard to work in.

Regards

That's a great thing indeed! IMO best results are achieved with multiple feed a day and small pots rather than large pots and only 1 daily feed.

No pot is to small in coco look at some clone grow from noreason (2lt pots, huge and healty as f**K plants)

Personally, I use 5lt pots wich lead me to a maximum of 4 feeding a day.

Thats one of 3 babes grown under a single 250W HPS... Look at the roots mass...

Regarding bluemats, I tried them once but also dropped them quite quickly.
Not comparable to a pump&drippers set-up

 

[The.Cook]

Just to be clear....I understand I should not be adjusting my pH based upon runoff, but are you also saying a nutrient solution pH of 7 is nominal? Please advise kind sir.

Dunno what you mean by "nominal", maybe its just a typo and u meant normal... Anyway, when you buy a substrate with an high CEC (coco coir is one of them, dirt / soil even more) you will find an indication of its pH.

For coco is something around 6.0, for dirt usually something more, and unless the substrate has lost his buffering capacity, that will be (in good aproximation) the pH your nutrient solution will be brought to once inside your pots (no matter if it was 5.5 or 7.5 in the beginning)

If you want to check substrate pH, just drawn a sample in ro water and check resulting pH (better if the sample is low in water content, the lower, the better in terms of accuracy)

@blueberrydrumz: my misktake here, not being clear enough. Please, do not think that pH7 is "equilibrium" as also pH2 can be an equilibrium as any other pH level.

In chemestry we refer to "equilibrium" as the point where the system we are taking into account will be stable.

For example, if we consider the system "RO water" it is stable at pH7 so that will be our equilibrium point. At the same time, if we consider the system "ro water+air" then its equilibrium point will be at pH 5.5 as water will react with CO2 normally present in air till that pH level.

If we add to the system dissolved salts, nutes, etc etc we will have an equilibrium point that will depend on all of them.

Just a matter of how much you want to aproximate real world...

 

[Pumpkin]

I'm new to coco.. I'm feeding 4 times per day in 4 gallon pots and upped my feeding slowly to 1000ppm... now I'm dropping back to 900ppm (finally i managed to burn the tips). Almost all the way through the grow I've had runoff as 250ppm... are you suggesting I need to feed more than 4 times a day to raise my runoff ppm? I'm currently happy with how things are going.. but always thought my runoff seems so low. Upping the nutes slightly obviously is not the correct answer. You can see the current size and age of my plants here https://www.icmag.com/ic/showthread.php?t=308241

Do you know if feeding twice as often would likely double or quadruple my runnof ppm?

Runoff of 250ppm seems to be treating me well... but feeding less more often could help?

Great article... I missed chemistry as a kid, but learning slowly as I get older. I'd love an article the follows the journey of a nitrogen molecule. from the bottle to the substrate to the roots to the plants to the runoff to transpiration etc.. I mean what happens to that guy in his journey? I don't understand the chemical changes that happen there at all... would be an awesome read.

 

[The.Cook]

Quite strange behavior as you're feeding 4 times a day with lot of run off so I'd expect to see inlet ec = out ec with just some slight difference...

Have you somehow treated your coco before seedling?

I'm also supposing you use mineral fert... Isnt it?

Anyway great plants man!

 

[Pumpkin]

I'm using Nutrafield COCO A+B. 5-10% runoff.

Glad you like my plants I read an article that your runoff should be about 125% of you input ec/ppm. Mine is more like 25%. Perhaps I need to lower my ppms and increase watering. But they are happy for the moment so I'll leave that to the next round.

A comparison grow for low ppms and high waterings vs high ppms and moderate waterings could be interesting. I'm sure there is a perfect balance in there somewhere It would be interesting to see if ppm runoff and watering schedule directly relate.

 

[Miraculous Meds]

I'm using Nutrafield COCO A+B. 5-10% runoff.

Glad you like my plants I read an article that your runoff should be about 125% of you input ec/ppm. Mine is more like 25%. Perhaps I need to lower my ppms and increase watering. But they are happy for the moment so I'll leave that to the next round.

A comparison grow for low ppms and high waterings vs high ppms and moderate waterings could be interesting. I'm sure there is a perfect balance in there somewhere It would be interesting to see if ppm runoff and watering schedule directly relate.

as long as ur plants aren't showing def, then I wouldn't do anything differently. the cook started this thread to explain weird anomalies that are usually answered by scientific understandings of the properties of coir. What ur experiencing I cant understand really, except to think that the plant is utilizing the majority of nutes ur putting in. Don't overthink it, if the plants are saying they are healthy/happy keep up more of the same. I have found that 1.2ec or 600ppm on a 500 scale is enough strength of food for any plant variety that ive grown, ( going on 80 or so strains so far). If my plants show hungry then I up the amount of times I feed, or the length of time per feed, I never add more ec that 1.2, its just not needed. u can use more than this, but if I can grow huge yielding plants at 1.2ec, and ur inputing 2.5ec like some of my friends do, n have somewhat equally as successful harvests as I do, all ur doing is wasting nutes compared to my feeding strategy, n definitely causing an issue to where u want to flush out the extra nutes in the coir by harvest. this imo, is where it becomes important to have a harvest flush. if ur feeding low enough to where ur ec is coming out where urs is, I bet u wouldn't have to flush for a single day, and u would have great tasting clean buds.

 

[The.Cook]

I stay around 1,0/1,3mS too from start to finish.

Hit some minor overfert when I tried something more while less than 0,9 caused my plants to drink and transpirate way too much..

Of course it's not law, you'll have to find out by your self as many different factors come in place, but it can be some kind of "starting point" for who's starting from scratch

 

[cdrchoad]

Thanks for the thread it has been helpful-

i have been experimenting with two different pieces of equipment in my grow.
1 The Oxy-doser this is a venturi aerating device of Japanese manufacture and I am running it with a O2 input from an O2 generator for medical purposes.
2 The UFB or ultra fine bubble generator also of Japanese manufacture using a normal air input.
I have clocked the Oxy doser with my dissolved oxygen meter when it was working (Sper Scientific P,O,S.) and it blew through 100% D,O, in about 10 minutes on a small volume of water. I have been using both devices in my grow and have been having some strange problems. My question is what are the chemical effects of high values of dissolved oxygen on the fertilizer and substrate? i have'nt seen any noticeable changes in PH and I run these overnight often.

 

[The.Cook]

If nothing, more of a biological thing than a chemical one i'd suppose

 

[KBD]

So I just finished my 1st coco grow and had some issues with mag. The coco I used was the gh compressed stuff that I flushed with tap water .18 ec tell the runoff was down to .2 ec. Then I flushed with .4 ec nutes.
I feed h&g coco line 4 to 5 mls per gal and everything was good for a couple weeks then mag issues stated. So I added calmag and within a week my mag was fine but leaves turned almost black to I switched to just epson salt and was fine for while but then I had to up the Epson dose every week or 2 to keep the mag issue at bay.
Does this sound like a problem with my ions and such or could it just be a mag hungry og strain?
I am getting ready start a new grow and was wondering if I should buy the more pricy coco being that comes with the proper ballance out of the bag or if I did fine charging the compressed stuff and it was just the strain that had the mag issues?

 

[The.Cook]

I usually flush it with ro water first and then with a mix made of RO Water + Tapp water till 0,4mS (consider that ec in my tap is almost completely Ca and Mg) than nutes till 0,9mS.
This is also the mix I'll start with.

0,4 seems quite low... also consider that Ca and Mg are really easely bonded by Colloids

 

[The.Cook]

Sorry man I feel I'm about to ask a silly question... What does "bennies" stand for??

 

[Phagoos]

Bennies = benificial bacteria

 

[The.Cook]

Quite difficult to answer, really, but I'd say if you'll be able to avoid salts built up you should be halfway through

 

[northernm]

Hey Cook,

great thread, lots of valuable Information!

I have a problem with the runoff pH of my coco as it is too low, around 4,9.
I already flushed it with pH 6,0 (EC 0,4), but instead of rising in direction of 6,0 it dropped even more to 4,6-4,7 (EC 0,4-0,5 as it should be)...

Any help is highly appreciated!

 

[The.Cook]

Have you tried do slurry-test it?

 

[northernm]

Not yet, but I will do this evening and let you know!

Edit:
Slurry Test pH 4,3-4,4

So the runoff pH of 4,6-4,7 is reasonable, but still i have absolutely no clue what the f*** is going on...
The other thing is, if i measure the Slurry EC with my Bluelab Truncheon it flashes to the max, which is 3,6+!!!
Runoff EC is 0,4-0,5...

Help...

 

[Miraculous Meds]

Not yet, but I will do this evening and let you know!

Edit:
Slurry Test pH 4,3-4,4

So the runoff pH of 4,6-4,7 is reasonable, but still i have absolutely no clue what the f*** is going on...
The other thing is, if i measure the Slurry EC with my Bluelab Truncheon it flashes to the max, which is 3,6+!!!
Runoff EC is 0,4-0,5...

Help...

That means u have a shit ton of nutrient salts built up in ur medium. it also makes sense why the ph is low.

Do ur plants look nutrient burnt? Id flush the hell out of them if so, with .5ec/6.0ph base nutrient, till u get a slurry test measuring around 1.2ec.

If u let ur plants dry too much between waterings, this happens often.