While I wait for new pH meter give less liquid ferts (to avoid pH problems) start from 7.3 then don't know where it goes prob somewhere between 6.6/6.

why did u flush... u need to feed her preferably without Ca bs it's starting to lock other nutrition

PH strips if stored right are just as good if not better then a pen. no batteries, cheep, no calibration they just work. The better ones have multiple indicators on a single strip for better resolution of the ph. They tend to be in pool supplies in big box stores. If your EC is high coming out. just means you need more runoff, or your measuring the runoff to soon. It will always be high the first little bit coming out. its the mid/late stream that you want to measure. But no need to do it if you are getting about 15% runoff of the pots volume. plants look good in the overhead pics. close ups are showing some issues.

Tips showing osmotic stress, yellowing. High ec. 1.9 is.just over the recommended 1.8. Tip to Remember for flush: ammoniacal nitrogen nh4+ does not readily leech from soil. Whereas nitrogen as no3- and no2- is highly mobile in soil and will leech readily. If you have over 20% of total Nitrogen as ammoniacal then you will have problems in your medium, this can creaye a high proportion of ammoniacal nitrogen (above 20% of total nitrogen) which will lead to uptake problems with other cations, particularly potassium (K+), calcium (Ca2+), and magnesium (Mg2+). This is primarily due to the increased release of H+ ions during ammonium (NH4+) uptake, which can lower the pH of the growing medium and inhibit the uptake of other positively charged cations. As long as she is within 6.2 and 7.0 ph and under 1.8 I'd keep plodding on a little sideburns are to be expected when learning. She looks vibrant and healthy just keep those.metrics within range she should even out ok.