No, this isn't normal fade... But what's missing from your diary is information on what nutes you're giving to them.... it looks like a lockout that, since your pH is just fine, is probably the result of too much nitrogen - but without that information, can't tell you for sure. And if it is a lockout, you can give the plant an entire bottle of calmag and it won't do any good - hence the term "lockout" .... an excess of nitrogen will prevent the plant from taking up any calcium... so if this is the case, you'd have to do a proper flush (3x the pot volume of pH'd water, in your case that would be 9 gallons per pot) and when they've dried, you can resume nutes but cut WAY back on any nitrogen-heavy nutes. You should also be watering so that you're getting at least 10-20% runoff each time as this will clear out excess nutes and any salts that have been building up...
Good luck...
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