Just sent this to Canna.
I would like to understand the ppm levels of your nutrient system better. Using the advertised nutrient values on your Canna Coco A and B a ppm calculation can be done to determine the ppm levels of NPK, Ca, and Mg in your product when 10ml of each are added to 1 gallon of water. (Percentage * 10,000)/378. (Phosphorus ppm) * 0.44. (Potassium ppm) * 0.83. The result is that ~395 ppms are NPK, Ca, and Mg.
N = 134 ppm
P = 47 ppm
K = 66 ppm
Ca = 120 ppm
Mg = 29 ppm
Yet, when I tested 10ml of A and 10ml of B in a 3780ml solution on a new, and calibrated, Hanna GroCheck meter I found that 10ml of A and 10ml of B in one gallon of water has a ppm value of ~540. This is a difference of ~145ppm, a deviance of more than 50% calculated. I have several questions because the results from the traditional formula to determine elemental ppm levels differs so greatly from the tested results.
How do I approximate the ppm levels of each element in your Coco system? Do I need to reduce the approximated ppm level of Phosphorus Anhydride to 44% of the advertised level? Do I need to reduce the approximated ppm level of Potassium Oxide to 83% of the advertised level? If so, then why isn't Nitrate subject to the same type of ppm reduction based on the molecular weight, like PK is?
What elements are responsible for the excess ppms that are not calculated? What concentrations are these elements in ppm levels?
Thank you
Hello,
Well let us start by understanding that ppm is not a decent way to measure. It remains dependent on the particular sensor on the probe. Some are Sodium Chloide based, others are other types. None measure 100% of the actual value of the TDS or ppm. Only Sodium Chloride will read 100%. Potassium nitrate will only read 67.5 % of actual, Potassium Phosphate will only read 37.5% of actual. So measured TDS done outside the lab is never 100%. EC or mS/cm is always a more accurate reading. True determination is done by analyzing for each independent element.
The values on the label are listed as the government wants it. Only 2 items are not actual percentage, P and K as you understand based on your formulation of 44% and 83% because they have to be listed as the Oxide products which technically do not exist (Ye Ole weights and measures) N is given as 100% N only so it is accurate no matter what form it is in.
So actual verses field measured is always lacking. When we give a value, it is based on EC then converted to ppm. It is also based on what most meters are calibrated in for ppm which is, I think, Potassium Chloride but do not really know. Now, couple this with the following fact: we do not state on the label everything that is in the mix. We do not have to, only what we guarantee, and only NPK. The mix is a complete fertilizer when A and B parts are combined and given what becomes available in the coco medium. So, it also will have B, Mn, Zn, Cu, etc. What you see as extra is the extra in it. Plus other non-essential ions that are baggage in every mix like Sodium.
Sorry, we will not divulge everything. Suffice it to say, for the type mix it is, it is ratio correct given the values in the medium plus has other things like organic acids, vitamins, silicon, etc, when using the entire feed chart.
Hope this helps,
Ralph B.
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CANNA Research North America
In conclusion it would seem neither of us are very accurate using ppm levels at all. The discrepancy will be there as a result of poor measurements when they are taken, and what is labeled on the bottle is only what is promised. There "might" be more.
I still think this info should be organized by a professional and placed in the nutrients forum.
Not something a person can argue: It would be nice to have it contained on the forum, rather than spread about on the net. It'd save some other poor shmuck from having to deal with all this.
Thank you for informing me about the nutrient labeling issues, jberry. It could have been done a little more maturely but I guess you got your point across. Canna was the resource I needed anway... not you. So no loss.
Bye.
