It really depends on the individual coral, flow rate and the level of nutrients in the tank, etc etc.
Off the top of my head, i work roughly to this:
- softies (zoas, leathers, mushrooms) : 75 - 150 uMol
- LPS (blasto) : 50 uMol
- LPS (acans, favia) : 100- 150 uMol
- LPS (torches/hammers) 100-250 uMol
- SPS (montis, seriatopora, deep water acros) : 200 - 300 uMol.
- SPS (acros) : 250- 400 uMol.
If you've got coral in there, I would make any changes slowly (over a few weeks) and observe that the corals don't start to bleach.
If not, personally I'd just get the blues to the right level for the PAR you want, then add in white until it looks good and dip them both a little bit to bring the PAR back into range.
I read a while ago that excessive red can cause bleaching, so careful with that channel. 👍🏻