Hmm, I'm mixing by weight if that makes sense. So at the initial mix the water would yes be too cold, but since the concentration is correct once brought up to temp the density would then be corrected.
If I have my slurry bucket filled with 4 gallons of RODI, and then 2.4kg salt (roughly 4x concentration so that's a brine) each gallon of this reconstituted with 3 gallons of additional RODI would make 4 gallons of 1.026 once brought up to temp. The program I have depends on four float switches being in the 'up' position (two at three gallons for rodi-primed and two at 4 gallons for brine-added in a 5g bucket for safety). Once all four are in agreement of mix prepped heat + a mix pump are activated.
If I can't get that to produce a fairly accurate mix I'm going to have to get a salinity circuit and probe. Then yes heat the water before adding the concentrate/slurry for an accurate reading.
My big concern though is that my slurry will precipitate, and I'd rather not try to use a powder, I'm worried it would get humid possibly clumpy and powdered salt + electronics don't mix.