Further reading: go check out cocoforcannabis.com guides and "dr photon's corner" articles on same site. They suggest a couple different things, but you'll see the same basic principles are at play.
Where you say "NaCl" buildup -- when they say "salts" they mean fertilizer. Unfortunately in coco, there can be Na+ cations.
Ca++ and Mg+ are important at all times and should be provided at "critical levels" of plant available forms around the root -- that means different things for different molecules.
Don't worry about what you were doing before. The basic procedure covers nearly all bases. I'll try to mention exceptions as footnote.
Coco should be mixed with 33% perlite, or similar -- and give or take. 70/30 bagged stuff is fine too. It is nearly impossible to drown the roots with regular volumes of irrigation.
Stop thinking coco is somehow different than any other soilless context. Some are better than others, but coco is 2nd tier compared to sphagnum peat moss (w/50% perlite or similar). Both have similar water per volume capcacity and air penetration if mixed properly with perlite or similar. The only thing special about coco is that if it isn't washed and buffered properly, it may contain high levels of NaCl and leech out Ca++ from your feertilizer whiile releasing any number of cations including Na+, K+ etc-- this is where that urban myth about how it needs more Ca comes from. Unbuffered coco will wreak havoc on your fertilizer formula, which is a big deal for soilless/hydro growing. We provied 100% of all needs through fertilizer and it nees to be at a particular ratio for best results. Sphagnum peat moss needs to be treated too, but it won't kill plants if it isn't (extreme and rare, but possible with shit ass coco batch).
Standard procedure:
Always fertigate (water+nutes) with 10% runoff or more. It should be a well-balanced diet at all times around 1.3-1.5EC (not including tap or other non-nutritious additives). I'll give a rundown of a good starting point below. Simply wait for at least 1/3rd weight loss and repeat. Don't let it sit in its piss. That waste water is fine to use with any plant in dirt outside but i wouldn't give it to potted plants.
The rest is just details. that's the meat above. Pretty simple, eh?
I'd suggest waiting longer between fertigations early on as this will cause greater root mass - when top layer starts to turn is usually 3/4th to a full day before a plant will wilt, so it should cover a workday or a full nights sleep etc if you miss it or on borderline schedule-wise for your attention - obviously avoid wilting, lol. Then, when you get a larger plant or into flower with well-established roots, you can do the more frequent fertigation with potentially greater returns - no less than 1/3rd weight loss from pot should be safe for frequent context and probably waiting for 50-75% loss early on. It may even drink fast enough you can do multiple irrigations per day if you want. That depends on rate of drinking = pot size x plant size. This 2-3x/day fertigation can match growth rates of hydro but you better have it callibrated or you'll just rot your roots.
Your fertilizer should ph-balance to a good spot, but if not, you need to do it. Any acid will work -- almost always have to ph-down between fertilizer makeup and typical tap water being alkaline. Acetic acid, or white distilled vinegar, is as good as any. pH drift occurs because of a poorly buffered solution. Seriously, change products if pH consitency is a problem. 6.0 is a good target. this gives you leeway either direction. you get much lower than 5.8 and it makes Ca difficult to uptake even if present at proper levels.
If you are always working with same volume of water, and pH out of tap is consistent (not always true), it'll require the same mL of acid each time.. take some notes and work it out in a precise manner. The 4-color 0.5pH resolution pH strips are cheap for 100 and easier to deal with than the cheap pH pens. I bouth 100 3-years ago and have 70-80 remaining. My fertilizer pH balances on its own to the proper level regardless of my tap fluctuation because it's pH-buffered to do so. Saves a huge headache.
Exceptions --
Seedlings - early on you should be able to avoid irrigating a very young seedling. Use a humidity dome until it sprouts, then remove the dome. This will keep the substrate moist enough for several days in even a tiny seedling pot. This ensures you got a tap root and more all the way down to bottom by the time you do fertigate. Go for a good wet-dry cycle from then on. Full strength fertilizer 1.3-1.5 EC is fine, but you could give 1/2 that and probably not see any difference. Even 'full' strength is quite mild, to put it in perspective. Light potting soil mixes for young plants probably have higher concentrations by comparison.
Clones - Can't let substrate dry, so you water a bit sooner than with seedlings or early vege. No roots, so it needs moist substrate around the buried portion of stem - don't keep it sopping, but do continue to water with runoff. Stick to water only or a 1/4 or less strength fertilizer - 0.3 EC, or 150ppm compared to 650-750.
Work out something close to these numbers from your fertilizer. There are apps that can calculate this from your guaranteed analysis labels. Simply type the percents in as well as dosage for each product and it will tabulate them for you. "hydro buddy?" think that is the name
https://www.angelfire.com/cantina/fourtwenty/articles/profiles.htm can work, i don't think it's as user-friendly as the phone app. Or, make a spreadsheet - just need a periodic table.
N 120-130 ppm
P 40-60
K 180+
Ca 100+
Mg 75ish
S 100+
Depending on your tap, you may need a slight adjustment with Ca or Mg, even N could have a few ppm in your local water. This is a very light concentration. If it doesn't keep up, raise overall concentration proportionally. This will depend a lot on local variables. I tend to have a high VPD, so i'm closer to the lower level of nutrient concentration needed. Plant may drink faster, but that doesn't increase rate of nute use, so higher vpd requires a llower overall fertilizer concentration, all other factors the same. and vice versa.
E.g. you may need 130ppm Ca. I have quite hard water. I'm sure i'm getting some healthy levels of Ca, though even when i switched from hard water to soft water (not recommended, but seems fine), i didn't have to change my formula.
Drop N down to 110-ish as vege growth ends - 4+ weeks into flower, not when the plant technically goes into flower. Vege growth = new leaves and stem elongation. Just to be clear on timing.
I used this exact formula or some proportionally scaled up version of it in coco for 2.5 years, give or take some experimentation. It works with 99% of plants very well seed-to-harvest and should not see anything by a slow moving tox or deficiency that will be easy to recognise and react to. Simple adjustments like that will be needed. Keep notes till it's ironed out.
this is also the exact, give or take some experimentation spiking p or k, same formula i used in sphagnum peat moss for 2.5 years prior. I'm very much looking forward to working with promix BX or HP topped off with some vermiculite (equivalent to perlite, but adds some Si). their bales come with a nute charge that is strikingly similar, except for lower K. It's ph-balanced and ready to go. No fear of killing plants with Na or some half-assed-buffered batch of coco slowing down your first 30 days of growth.
What you feed the plantis 100% about the plant and not the soilless medium of choice. Coco is fine. It is convenient. It's a bit of a risk, though. It's not "greener" - it wastes a shit-ton of freshwater, i guarantee that is equivalently bad for the future as digging up bogs.
You'll find that numerous different brands have a very similar ratio to the above and at a 1.3-1.5EC mix rate by instructions -- JR Peters "Jack's Hydro part A", Souther ag's hydro line, masterblend's hydro line, athena's proline, floraflex pro line i belive -- all a base hydro paired with calcium nitrate and magnesium sulfate (any old foodgrade epsom salt). It's not an accident. This formula rocks. Don't be afraid of dry nutes. I grow 80sq ft of weed per year and spend 35 USD on fertilizer per year. It should be a tiny portion of the total expense of someone is ripping you off.
