Hey man. Sorry I never got back in here.
I'm no pro. So take it all with a grain of salt.
I feed everytime with promix... unless I'm out of solution and time.. then I'll hit gen with a little water till he next time I get in there
Rykus has good info in his thread about "flushing" and not giving plain water... I.e flush with 200 ppm. By going back and forth btw water and food you are doing a feast and famine wherein ph will be all over and plants get stressed
I do promix hp with cut in half with chunky perlite.
Chimera has a good promix thread. The overall consensus is that 6.8 is ideal. Worked fine for me.
I am in tap @ bout 220ppm 7.3. Ur high ph is curious for lower ppm
My mix always swings up. So in my last run of promix I went with 6.5 and let it swing.
Honestly don't worry about runoff. It won't be that accurate.
I have fed at 1.0 during flower. The plants slowly yellowed the whole time. But the yield was awesome as well as quality.
Lastly. I'll say that in veg he 1:.666 doesn't cut it for me.
I've done 1:1 with better success
And I've also been recommended 3.7g hydro:2.45g calnit.. the numbers look good there too.
I mix the proportions of hydro and cal not that I like.... then add water till it gets to my desired strength. If I'm gunna add epsom or silica I do it then. Then pH.
Ok.. idk if any of that helps. But it's what I've done
But 3.7 & 2.45 is the 1:.666 ratio, so while you're saying that ratio doesn't work for you you are also saying it looks good?
Also I'm not sure how it matters but jr peters recommends adding any Epsom after the Jacks but before the calnit.
Not trying to be confrontational just want to clarify so I'm understanding you correctly.