Another idea is to run some distilled water through the soil, when you get about 10-15% runoff use a ppm meter and test the EC/PPM of the runoff. If your ppm of your runoff is over 1700ppm, it may be a salt issue where your soil EC is too high and frying your roots which will dry out your plants and also will kill off beneficial microbes in the soil which will produce less nutrients for your plants.
I noticed you are using "filtered tap water" what type of filter are you using. If it is something like a Britta pitcher filter they are only good for a very slight reduction of ppm. I had tap water at 375ppm put it through a britta and it came out aroudn 330ppm, hardly any reduction. If this is what your doing to filter your water, its very possible you have a salt build up.
Also if you are not letting enough run-off per watering these may also lead to salts building up and not being leeched from your soil. I would take one of your plants showing slight defficiency and flood the soil with about 3x as much distilled water as the pot size..See if this helps the plant recover.
Another option would be to get some Epsom salts and distilled water. Using Epsom salts and water as a foliar spray sort of will "reset" your plant and help it get back on track by helping it "flush" its system. You can try this too.
I noticed you are using "filtered tap water" what type of filter are you using. If it is something like a Britta pitcher filter they are only good for a very slight reduction of ppm. I had tap water at 375ppm put it through a britta and it came out aroudn 330ppm, hardly any reduction. If this is what your doing to filter your water, its very possible you have a salt build up.
Also if you are not letting enough run-off per watering these may also lead to salts building up and not being leeched from your soil. I would take one of your plants showing slight defficiency and flood the soil with about 3x as much distilled water as the pot size..See if this helps the plant recover.
Another option would be to get some Epsom salts and distilled water. Using Epsom salts and water as a foliar spray sort of will "reset" your plant and help it get back on track by helping it "flush" its system. You can try this too.
