New to MC and reservoirs in general, but the sample of MC 2.0 is finally seeing action (drip DTW). I make up 3 gal of MC every 2-3 days, chill it below 68F w/ frozen bottles while it bubbles. Even after sitting for 2-3 days of use, there is no smell or cloudiness - again new system (clean). It is very possible that if you've had bacterial/organic growth, it's now in all of the drainage lines, air-stones, water pumps, etc. While it's appearance may be transient, it's very unlikely to ever be fully eradicated, just kept in-check...until conditions change of course.
No but you can foliar feed Cal-Mag, to what effect I'm not certain - but you can rapidly address it.And we cant just inject the plants,