I've been liking my results with MC 1-part in coco, with no calmag (MC supposedly has enough in it). I add the recommended grams/gallon and then check the ppm just to make sure it's in the ballpark, adding the ppm of my water (150ppm). Many here have recommended ditching ppm and using an EC meter to avoid confusion, but I haven't worn out my ppm meter yet. I figger that if I weigh the recommended amount of MC, any odd ppm reading is the fault of my $20 meter, but checking ppm does let me know if I forgot to add the nutes or added a double dose. These Mephisto Sundae Thumper testers are 6 weeks old in coco with MC 1-part only (currently 5 grams per gallon, ph to 6.0). There are probably other ways to keep track of runoff without the kids' orange Haloween bucket:
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