Thanks, Fishly, that is exactly how I was thinking -- if I'm going to the trouble of RODI water I might as well treat it as a blank slate and put in what I need. I come from an engineering background, and do realize sometimes that means I try to solve a problem that isn't a problem, but in this case it just seems simpler.
5) Stir it until the Equilibrium has dissolved. (it is hard to dissolve).
IGNORE THE PH
Over time the fish will adapt to the lower mineral levels, and you will be removing whatever the water company has been adding that holds the pH so high. This will take time. Let it. The fish cannot adapt to new water parameters (especially mineral levels) quickly. If it takes a month, let it.
Well, my concern is without a bit of bump on the acid buffer side it's going to take much longer than that. Maybe I'm wrong, but I am not doing water changes very often -- my bio load is low (though growing a bit, literally), but the plants seem to be slowing the nitrate rise. I am actually down at about 5ppm with the last 25% water change, which is only the second in 7 weeks. If my math is right unless I put the water I add more acidic, it will be a year before it gets in the low 7's.
Or... I do more WC's than needed, but wiping out almost all nitrates -- won't that be bad for the plants?
What I'm mixing is almost identical to what you suggest, thanks for that. I am just using the commercial acid buffer rather than that you get naturally from peat.
What I'm confused by is without something quantitative, how do you know how much peat... what is going to eventually drive your recipe toward a specific ph? Are you saying working the alkaline buffer down to a target KH will eventually just naturally end up with the right pH?
More concisely -- what keeps this process from over-shooting and ending up at pH 6? Or under-shooting and hanging in the high 7's?
Or are you saying just now and forever more ignore the ph?
PS. Thanks for the tip on Equilibrium, I had some (I thought) precipitate in the bottom of the buckets, and wondered about it, but didn't think too much. I bet I didn't dissolve it well. Is it better perhaps to add that directly to the tank after the water to be sure it all ends up there?
But we are telling the OP to add the necessary chemicals.
Yeah, "Chemical" and "Natural" and even "organic" have taken on a life of their own, and meanings that really are not there. I hate seeing products advertised as "containing only natural ingredients". As though they might contain isotopes manufactured in accelerators that do not occur in nature.
After all, ricin can be made from "natural" casterberry beans, arsenic is naturally in many fruits, and radon comes up naturally from the ground.
Marketing has deluded us into thinking that something is bad if it comes from a lab, and good if it comes from a tree, and while there's probably more bad from labs than bad from trees -- we mustn't fall for the marketing lines, but read the ingredients and whatever else we can.
I don't, for example, object to peat as opposed to acid buffer -- I just feel obligated to measure it. Maybe once I've done aquariums for a lot longer my need to measure will abate. Right now I'm (knowingly) going overboard a bit on testing and quantitative approaches, as that's my comfort zone.