Nice going Al! I cant give much advice re the fade and spots on MH but I think
Could be right...
Also - are you letting them dry out between watering/feedings? I mean like really dry, borderline wilting dry. They really need good wet-dry cycles in soil. And raising the pots off the floor might be a good idea too. It will stop the rootzones getting cold when your temps drop into the lower 60ºs.
It’s hard to let them dry out like that - but really push yourself. If you think they need water - wait! Unless they’re already wilting of course. But if they’re slightly droopy a lot and the pots are wet, it’s because they’re too wet too often. This can slow down the soil biota and can affect the relationship btw roots and soil biota, impeding uptake of necessary ‘things’.
And I’ll keep saying this until you get one - Some kind of humidifier! I realise one can’t always just buy stuff but your plants won’t thrive until the RH is higher and stable
wait until they’re fully dry before you give them any more