Without taking the most scientific approach possible I pay zero attention to anything in my FRESHWATER SUPPLY besides
TDS anymore.
What comes from your
RO unit will either depend on if you use
DI also {I would not}and how well the unit handles your source water.
Some units will leave up to 10% of original
TDS without using the
DI media.
So don't expect your
RO to be zero necessarily.
My source water is 7.6 ph /2-3
kh/ 9
gh so not real bad 'according' to many....
My
TDS for this source water is 350 -400...That is pretty high.
The thing with ALL these test and the readings is that is all you get..
You get a reading with NO explanation of why..So while 0
TDS may seem easy to comprehend any reading over that doesn't tell you what is in the water.
I mix my
ro and my tap water to get the water to where I want it.
I only know where I want it from trial and error..
I like for my rams to be in water from 65 -110
TDS and over 80 degrees..I don't measure anything else..
While this may seem like the way of a mad man[ I am] my trial and error has been happening for at least the last 4 + years and I have done reasonably well with my rams..You can search my threads or find me selling them on Aquabid.. I breed EBR/GBR on the regular..Other fish also but not in the same water.. I raise my rams in my tap straight and it makes them a better stronger fish I am often told.SO if you are not breeding and know how to acclimate fish to water you are best served staying with your tap.
It is always hard to pass time honored info without a little opinion so disregard this if you know it all..

I got nothing against seachem, they are a very reputable seller/mfgr ,but all that add this and that and then this ! You just spent
RO filter membrane to remove that crap !Throw your money out the window on the free way..You'll get a better return
IMO. Just mix your tap back in and pay attention to the amounts so you can do it the same every time or know how to adjust it .
If you stay hell bent on chasing Ph/
Gh/
Kh you will spin and your fish will suffer.
Rams of all fish will not tolerate much of this...