If I've noticed anything in the share your dosing thread, its that Greggz and others are reducing K and Fe.
I simply have to question Tom Barr and his contention that K levels don't matter. 100ppm? 50ppm? 30ppm? 20ppm?
I can only to speak to my reasoning for lowering K. In the past, I was raising the KH of my RO water to about 4 dKH. Using K2CO3 that meant a lot of K....50+ ppm. I tried many times to lower NO3 & PO4, as I just thought it should work. It never did.
So my theory is that maybe my high K values led to a need for higher NO3 & PO4 (Mulders Chart). So I decided to start lowering K and everything else at the same time. Things were going along well.
Then I was having a discussion with Joe, and he mentioned that he had been speaking with Vin Kutty about a guy from Germany who keeps all his tanks with K lower than Mg with great success. So I said what the heck, I've gone this far, might as well jump further down the Rabbit hole.
So then I started slowly lowering my KH and total K even further. KH now is just about 1 or so, and I am using MgNO3 instead of KNO3. So I REALLY lowered my K. At the same time I began lowering everything else in proportion, including micros. I figured the worst thing that could happen was going back to my old dosing scheme, which I was all in all I was pretty happy with.
So far it has worked out very well. Biggest difference is nuisance algae like GDA on the glass is totally gone. I'm still paying very close attention to see if any deficiencies pop up, like what happened to Joe.
You want to see something funny? I keep meticulous records of everything (which in itself would be a great topic for discussion). I posted this in my journal but I'll do it again here. This is my dosing over time. You can see my tank has been one long experiment.......and still is.
Also shows that the system can withstand some pretty wide swings in dosing yet somehow manage to do OK.