DANGERDAN
Coco is a hydroponic growing medium, simply a physical habitat for the roots, like hydroton or perlite or net pots, or sand... You can treat it like growing in soil, which is a comfortable and basic growing strategy that most beginners are familiar with, so it's popular. Plus, is shows an excellent repurpose of what would otherwise be waste. Low CEC also = CONTROL. It's easy to flush and there is low holding ability, So that can be used as an advantage.
It's similar to growing grass over pure sand, or golf course putting greens which are constructed out of pure sand (newer builds or renovations). The problem lies in low or insufficient CEC in both platforms, sand putting greens & coco. Spoon feeding with frequent, light apps is the key to keeping nutrients suspended in the root zone. Daily, bi-weekly, or weekly apps are common even on a large scale, so feeding in coco every time would make sense.
How we manage that into our program is to figure out how much of each mineral the plant uses each day. Usually it's Nitrogen (turfgrass is average .1lb/ week N) and then use just the right amount to get us to the next application. So it's like applying 15 days worth of nutes every two weeks/14 days, one extra day's worth just as a buffer. This would be my strategy for coco and it would look like pipettes of small amounts each time; perhaps that is a common theme in the need to flush all the time. Salt buildups are not an issue for programs that apply just enough minerals to sustain proper plant functions.
I see Coco similar to hydroponics. Growing turfgrass on top of sand is a close second, which would be the most tangible blend of soil science & hydroponic plant biology to relate to. Low CEC is inherent to both growing systems, which is limiting but also liberating. We as pesticide and fertilizer managers must be aware of leaching phosphates and nitrates (NO3- , PO3-) in these systems. My concern is that 300acre golf courses next to streams, lakes, rivers, and oceans and under rainfall do a better job at keeping the environment clean than a bunch of potheads with 4 plant grows scattered along your block. So when I read about drain to waste it just makes me cringe because I understand the legal liabilities associated with proper waste disposal. We know we shouldn't put batteries in the trash but some of us do so, it's not like a cry out for this will change people's hearts. I don't grow in coco and I see very successful grows with this method so I cannot say "don't do this". However, if you went and did something with the rinsate like use it for your flower barrels then reward yourself for using your brain.
Coco is a proven growing medium in which people find great results. I've learned much from watching some members grow in coco around here and I am very impressed. Wouldn't once think these people don't care about the environment, all of us around here seem like we care about plants and animals.