Update:
I think it is spider mites.
Don't have magnifying lens, but I think I see them.
I sprayed the leaves (bottom side) with permetrine 0,25 % water solution.
I'll go to the store and get something else later.
I hope it helps.
Should Leaves recover now or are they lost?
Thank you!
This is a great forum!
if you think you see em, snip off part of a leaf that you think might be thickest with the critters and take it out to someplace with light suitable for reading.
you can fill a drinking glass or clear bottle with water and make a ghetto magnifier to examine the leafs.
if it is spider mites you should see a gang of little critters that look like wee little crabs or tiny spiders on the underside of the leaf section. they should be even smaller than a "full stop" > . <-----one of those.
if so. you got some work to do but you can save the plants.
option 1) put NEEM oil (diluted to about 50%) on a soft cloth and wipe the leafs one by one. (both sides)
option 2) use good quality miticides availible from your builder's merchant or garden shop. (any pesticide you use will have long since dissipated by the time you start flowering.)
option 3) kill it with fire! rip up your plants, sanitize the entire area and all your equipment including fans, fan blades, fan shrouds lights, vent covers, filters, etc with bleach and start over.
option 3 is most certain to fix the problem, but option one and two are good.
if you can kill the little bastards your plants will recover nicely. they are really just like tiny tiny aphids. they suck on your plant untill you killl em then the plant is just fine.