Grr... misread pH, now deficiency

This is more of a vent. I used one of those cheap pH tests that the hydroponics store sold, guy even recommended it, but maybe I can't read them for crap. Looked like my pH was fine, around 6 to 7 but who knows reading those color codes.

3 weeks into seed germination my leaves went from beautiful dark green to light green now. First thing I go to is the water, using tap, let the water rest for 24hrs for the chlorine to go away, general organics range of nutrients mixed immediately before using, and then the assumption that my pH was still good. However, I went and got a good digital calibrated pH meter and it turns out my tap water is about 7.8. Ouch.

So, I've had 3 waterings in so far, my plan is to make up a proper mix, balance to the pH to the low 6's and flush the plants. Using coco coir, I'm pretty sure I can just do a 40-50% runoff, drain the runoff from the tray, and things should be back to kosher.

This is my plan, if this sets off any warnings for anyone, let me know... but as I said, this is more of a vent. I know first time growers tend to "over do" things, so I have just been watching every day, taking notes, waiting and thinking, not rushing to judgement. Temp range has been good, humidity has been good, all recorded daily in my grow journal. Roots are already coming out of the bottom of the 3" pots. I'd say, as long as I fix this pH nutrient thing tonight, and they rebound, I should be ok.

It should green back up in a few days being they are in coco coir. It would take longer and more flush water with soil. Looks like you have your bases covered, I don't see any glaring oversights, but I'm no expert. Anyhow, I wanted to add that it's nice to see someone take their time and write a well thought out all info included question. I see too many questions where they give little insight or detail into their grow and just expect riu peeps to figure it out for them. Please update the progress, thanks!

I took my time and pHed a gallon of water to 6.2. That pH down stuff is no joke, I put in like 5 drops from an eye dropper and it went from 8.4 to 3.8! Got it back up to 6.2, added my nutrients which brought it down to 5.6 (1/4 feed of the general organics schedule). I flushed about 1/3 of a gallon through the plants, pHed the run off at 7.2! Drained the tray, flushed again (gotta love coco coir for this trait) and the run off was 6.2. I know I need to get it down to 5.8 to 6.0 but I'm happy with this. I'll monitor it for the next three days, but I expect by Sunday things should be better (color should be back, rigorous growth should resume). I'm just obviously going to have to pH every time, what goes in and what goes out.

As for pictures, I'm too concerned that GPS data could accidentally get attached, so unless it's a catastrophe, I'll avoid pics as much as possible.

It was like flicking a switch. Growth started right back, color returned within 48 hrs.