I feel a little responsible for resparking this thread up lol. I just browsed through but from my perspective it seems like its gotten lost along the practical vs technical vector. Im not sure who wrote what but my question is what is the practical application of knowing whether coir is inert or not. In actuality from my personal experience it can behave like both. It depends how you use it. Technically its not inert it breaks down and has a cec above 0 so technically its not. But the argument really falls apart if its about supporting a cannabis plant from start to finish seed to fruition with no additional inputs or ph adjustment. In my experiences the plants will be alive... but in any sort of application where your trying to produce anything with commercial intent doing thats gonna be a joke. Coco just not break down fast enough not without the biology to break it down present. Worms eat it. It can and does have organic as well as inert type properties depending how you use it. Its both in its potential applications.
That being said the cec being above 0 and taking into account the mobility and variability of the elemental uptake rates across the growth cycle, coir is a medium unsuited for recirculation and e&f type setups. Essentially what happens is the solution becomes IMBALANCED, so the ratios of the elements become unsuitable and essentially toxic to the plants roots and this manifests as something that looks like deficiency. When in reality its a lockout from a imbalance.
Check is cation exchange capacity which also adds a layer in that this is talking about cations specifically and that relationshio with the medium. Now my chem is amateurish at best but my understanding is that this means ions with a positive charge. Nitrates calcium and magnesium being the most relevant to cannabis cultivation. The differences in elemental uptake rates means that the main culprits in this cec thing are cal and mag, where on average nitrates are removed from the medium faster and more easily by the plants than can and mag. Cal is the slowest and least mobile of the elements and can build up in coir in a imbalance manner if not refresh/replenished/flush with a new solution source with the nutrient profile balanced. This is what happens in a hydroponic rez thats recirc if you go too long without a change. Calcium builds up in the solution because the plants eat all the nitrates first.
This is why rw is better for recirc than coir. Because once the rez is imbalanced and you keep dumping that ca laden rez water over the coir it sticks hard to the coir and is hard to unstick.
Rtw is where coir shines and is at its full potential imo.
The other variable im seeing is that these companies are designing these products. Often to function as a package. I run canna and don't deviate from their product too much. The crew I used to run with went to a private info session with sales rep for Canna, (Really nice Dutch guy my ex boss is tight with) and they have designed their product to work best together. Other brands would likely do the same. For better or worse quality.
That being said this Canna guy actually seemed to know very little about growing weed and was more of this like yeah yeah don't sweat the details just do what it tells you and it will be perfect. We tried things his way vs ours and it was not working correctly the ways that he told us. So we shot that shit down. My point being is regardless of technicalities what works is what works. The thing with this nutrient stuff and branding is that these companies are formulating this shit to have a averaged amount and ratios that work for the broadest customer base with the largest variables in grow style/experience/etc of potential customers. The nutrient profiles of these companies are pretty similar overall there just presented to you in xyz products in various amounts of bottles.
No modern coir company worth their NaCl is not going to replace the K and Na present with Ca and Mg. No is toxic in high concentrations and K is required in more elevated levels in the later parts of the cycle.
Maybe some more stuff I could add but this is getting to long for one post lol.
Just my take on where this threads vibes are at.
Let's not fight boys lol. Its only weed at the end of the day. Feels like catching ill vibes about something like mj is counter intuitive to the whole point if you ask me.