Hi Gareth (@Wookii)The 2hr aquarist doesn't 'recommend' a pH of 6 to 7 as a target for plants, that is just the result from a low (2-6) KH and CO2 injection that he does recommend. Far and away the overriding message from that article is that pH doesn't matter, but KH matters in some cases.
You are absolutely correct and I chose my words badly. In my head, I was very clear what The 2HR Aquarist was saying. His message was as clear as a bell. Quite how my brain managed to mangle it, I don't know. Well, I do really - but I'm not going there! Anyway, thanks for correcting me.
As mentioned before, the acidification of the growing medium for a commercial outfit will be to prevent some micro elements, such as iron, from becoming unavailable not because the plants specifically need an acid pH in order to grow - that is what Christel is referencing.
You may well be right. I'm just seeking clarification. If @Christel finds time, I look forward to hearing what she has to say.
JPC