Yes flushing can actually release more nutrients and that is exactly why flushing can do more harm than good. Flushing and adding calmag are the two most unnecessary things people do when they start to see an issue with their plants and those are typically the two most common suggestions. Another thing, some of the worst advice you can get comes from the guy at the hydro store or nursery. They're trying to sell product and most of them don't know what they're talking about.
That plant is far enough along that I'd just give it plain water and ride it out. Especially since it's an autoflower. It would be different if it was a long flowering sativa with another six weeks or more left. It's not worth the effort chasing this and that and could actually do more harm than good. Just my two cents.
well said! Flushing is highly overrated and often times causes more issues than it can solve. This is the newbies way to ';fix' issues..flush flush flush lol..when in reality it is completely unnecessary and not worth the stress it creates. Not to mention that people will flush with plain ph'd water, which actually does absolutely nothing at all to 'clean' the medium..as the cec sites that are occupied with the 'unwanted' elements, will not be unbound from their sites with simple water..its why people who use cal mag think it's the miracle fix..they think they had a cal mag deficiency and they flushed with it, now all is good..when in reality, the calmag, has nothing to do with the plant needing it..it simply has the power (calcium and magnesium to a degree), to clear the cec sites of either the aluminum, or hydrogen that they have clung on to over time..by clearing those sites..the plant can get back to a healthy rhizosphere and continue on. The problem is, that 90% of the people have absolutely no understanding of any of this or why it works..so they continue on with their thoughts that calmag is needed..calmag is missing..it comes from uneducated people with regards to plant biology!
Testing runoff and such..useless and not needed. Plus if in organics like OP is..ph is mostly irrelevant as well..so many misinformed people and the worst is..they spread that info and newbies will pick it up and then spread it too..its why finding the truth in forums for newbies..is very time consuming..so much to filter through and in the end, one has to take it upon themselves to truly learn about plants and how they work at the base level..most will not know this or care to learn it. Happy growing OP..to me it seems the plants are naturally getting to the end of their life, and the yellowing is natural..i highly doubt you have a toxicity or lockout..if anything..it's missing some food, but from the looks of it..she's finishing up naturally. I would however look into the watering practice..odd that your medium seems bone dry near the edges and damp just around the stem. How much water and how often do you give it?