Optimising Nuttrient Ratio's for Cannabis Production - A seymore experiment

[seymore_budz]

Loads of male bits all over the bottom of both plants.

Shitty to here about Seymour.

My own fault mate. I'd had three previous runs of Sensi Seeds beans and they were all shit apart from the Shiva Skunk. The White cheese was so bad I just binned it. Got bit three times and thought, fuck it, letsntry a forth The Bird I was sure would be OK since it's a collab with Humboldt seed company. Well I was wrong :)

The other reason was I'm new to this level of detail. I know lots about the products, but not about the chemistry required to manufacture your own nutrients. I could probably knock up something coherent, but not really know what I was doing and just follow the recipe.

I've learnt so much since starting this experiment. I didn't even know what a pycnometer was or how to calculate estimated elemental values based on the guarenteed analysis or solution density. I'm now at a point where I have a tool that I can plug in the ml/L of each solution and confidently say that plant has enough of everything. Just waiting for my lab results back to confirm everything is sweet. I can also print out graphs to visualise ramp up and down of macros etc. And cut things down to the bare minimum! I like growing hydroponics, but I don't want to be contributing to environmental issues by slinging P down the drain when I don't need it. And wasting money :)

I'm quite confident after doing a shit ton of research that we simply don't need PK for cannabis. And all we're doing is throwing money away and damaging the environment. And only so the MDs of these nutrient companies get rich. The more I've researched things, the more it has become clear that a lot of the shit we thrown in is simply not required. I may do a detailed post about it in the future, but tolerance to overfeeding is a lot higher than you think. Microelement toxicity is more likely due to them being chelated and can be taken up easily. That and they're not needed in large quantities. N, P and K have a much wider tolerance band. For example, I've read several detailed studies around nutrient requirements specifically for cannabis. They all differ slightly, but cover a wide array of cultivars. Based on their research, I've set my tolerance bands to the following.

N: 80-240PPM
P: 15-90PPM
K: 100-170PPM (can go way above 300ppm without issue)
Ca: 125-300PPM
Mg: 35-100PPM (15-150ppm without too many issues)
S: 15-200PPM

You can also checkout the standard recipes like Hoagland vs LARS. They differ quite a bit, but I'd bet my left testicle both would grow a green weed plant

I'm pretty confident that most base nutrients sold in hydro ships are just smoke and mirrors. Take calmag for example. If you know the density and full GA of the brand of fertiliser you're using, you could just up the a or b a little depending on the composition split. Of course there will be differences in quality etc due to the quality of ingredients etc and some will have slightly different ratios of NH4+/NO3- depending on what the target market is. Cannabis doesn't like NH4+ a lot. In soil, bacteria will convert it to NO3- but in hydroponics, if you don't add the nitrofying bacteria, it won't be present and will cause problems. Terra Aquatica can do both soil and hydro, but the NH4+/NO3- ratio is pushing the limits for hydroponics I think. Suppose that's the trade-off when you're trying to cover a wide variety of species.

Anyway, talk about a tangent! I shall be back soon :)

[seymore_budz]

Hello guys,

This diary is done, but I thought I'd come back and let you know the results from the analysis I've had done (twice).

So.... the first one came back and didn't match what I had at all. Everything was through the roof and some were 110% over what I had calculated. This threw me a bit, so I reached out to Terra Aquatica and it turns out their ratios are w/w not w/v and they don't specifically say on the bottle. I've read hours and I mean HOURS of material around how to calculate this, and the general consensus is that if not specified, it should be w/v if its a liquid fertiliser. Anyway, updated my calculator and ran the numbers again, and now they're more out for some! This was proper confusion, but I put it down to me being a spanner and not adding the right amount of each component.

I think ordered the equipment necessary to measure the specific gravity of each component, did Everything properly and mixed up a second solution using a set of scales with a precision of 0.001g. Sent that off and the results came back correct for some and 110% ^ for others. I couldn't understand it! Back to the books I go, reading a shit ton of stuff, double checking my calculations and even reaching out to a chemist to verify my calculations and everything seemed correct. Then, I thought, let me try without converting the oxides to elemental values.... wolah! The numbers matched perfectly. So every book, Internet article and person I've asked has said, if it's listed as an oxide, you convert, but it would seem Terra Aquatica was like, na fuck that, we will list the oxide and use the elemental % to really fuck with your head.

Anyway, I plan to do a third and final calibration later this month. Moral of the story is, never take things for granted. If in doubt, ask the manufacturer!.

On a tangent, you want to know what the best EC value (in theory) is according to my calculations after months of research and fucking about killing young plants? I'll tell you anyway, using Terra Aquatica, the optimal EC for cannabis is 1.8EC. This can change up to 30% both ways depending on the conditions. I plan on running some experiments over the coming months and some I'll document as a diary. I've not run this formula on anything older than a couple of weeks, so I'm excited to see if it works :)

Here's my min/max/optimal table ad mg/L (PPM) for productive growth.

Code: Select all

Element	minimum	maximum optimal
N	100	200	160
Mg	15	140	35
Ca	100	300	130
P	25	90	30
K	100	400	100
S	25	200	50
Si	5	20	10
NH4	0	60	5
B	0.1	1.5	0.4
Cu	0.01	0.2	0.03
Fe	0.5	3	1
Mn	0.2	1.2	0.6
Mo	0.001	0.05	0.02
Zn	0.05	0.6	0.2
T-N	80	220	168

I will do a long, detailed and boring post later if anyone is interested.