i agree with rasta, flush with double the amount of water the container holds.
for example, 1 gallon container gets two gallons of water.
it might not be possible in your case, i did notice those big ass bags you're using as planters.
also, when you flush, check the ph of the first round of waste (flush) water to leave the container... to make sure you got the ph in range ...& are not contributing to lock out of any type.
oddly, i feed my soil plants regular tap (not ph'd) with nutes & the water from my dwc rez changes & the run-off water has been comming out at 6.3 ish.
no, imo, after a flush just let the soil dry out real good ...as per rasta, feed ph correct tap w/ light epsom mix for 3 to 5 days... you should see a marked change in a week.
cal-mag, homie, is your best fucking friend... and imo solves all kinds of issues & your tap water is 77ppm ...which is light on the cal.
i use botanicare's version (has other essentials in it, is liquid, is cheap, lasts long) but epsom salt works too.
funny my soil (mother) plants i put into flower 3 weeks ago, to make space for a new round of goodies, are starting to look the same.
since there's some in the cabinet, i will have to try the epsom