The 6/9 recipe has all the elements needed so no additional inputs like
calmag are necessary. In fact adding
calmag to 6/9 disturbs the ratios and might be one of the reasons for build up. Florakleen is IMO another one of those products just to spend money on. Remember keep it simple with coco. The more things you add the more confusing it is to figure out what's happening when something isn't right.
Nutrient build up is controlled by not overfeeding in the first place. I don't recall what 6/9 comes out to in EC, but sometimes it needs to be diluted for younger plants, or a different environment. The ratio is what's important.
I always feed in coco from day 1, and I try to play into the EC by assuming the coco will retain more than what will come out. In other words I feed light enough to make the EC build up in the medium work for me instead of against me.
If I don't know the strain I like to start plants off at about 0.6EC(300ppm) and go up from there as they get bigger. I typically max out at about 1.2EC(600ppm) at full flower and then taper back down. Mind you this includes my source water which is from tap at 0.3EC(150ppm). I like to mix R/O with a bit of tap water to get to that 0.2-0.3EC(100-150ppm) starting value. It has helped to stabilize pH in my experience.
There's nothing wrong with adding pH up if your pH is too low. It's probably potassium silicate, potassium hydroxide, or some other form of potassium.
You should be at 7 feeds a week at least, not 6. An EC reading of 4.0(2000ppm) is WAY TOO HOT. I'd prefer if your rez reading was down in the 0.8-1.4EC(400-700ppm) range. It means your plants are using more water than nutrients. You need to top off the rez with straight water periodically to keep the EC from rising too high. Yup you deifnitely don't want to feed 2000ppm everyday. That's how you get build up. You want to feed much much lower. Somewhere between .8-1.4EC(400-700ppm) depending on stage of life and environment.
When you feed low and consistently you keep on pushing out excess nutrient as well as keeping the salts from binding to the coco. If the coco stays wet the salts stay in solution, If you feed too strong everyday you get build up regardless of sound watering practices.
Classic signs of too much nutrient being used. Just remember that you can make 6/9 and then dilute it with water to your desired strength level.
That was when I chopped them. I pulled them out of the 3.5 gal pots to check the root mass. Only filled them to about 3gal though. Thank you!
