I hear you on that one. Thats how i like my coir too.
But people have a lot of cal, mag, potassium, and sometimes phosphorus issues in coir.
Look at their availability on the chart. If you see, below about 6.5, it doesnt matter how much there is, the plant cant absorb much at all.
Its ideal, i find, to let your ph creep up towards the 6.5 mark between feeds. Then bring it back down to 5.8 each feed. That ensures the plants get everything they need. A little upwards ph swing, is actually a very healthy thing.
Bare in mind too. Deficiency and toxicity, look the same, until they're well advanced.
Lockouts and deficiency that charts show, are very advanced. The plants would have been suffering for days. If not weeks. Especially if its deficient.
I find the ph chart, soooooo handy, to identity toxicity or deficiency, before it progresses.