orange chromide stocking ?

Is it possible to have 2-3 orange chromides in a 15g? The ones at the store are 2" now. I'm thinking of upgrading to a 20L or 29 a later date.
I'm i right in assuming that red chromides are orange chromides?
I was also wonder about their color, At the store they are pinkish not orange, is that because they are not in brackish water at the LFS?

i think i'm close to deciding if i'm going to get the chromides. just a few more questions. 1. I just measured my ph it is 7.9. is that ok?
2. Also i know i have hard water which is good, but should i still have a type of substrate to buffer. Will marine reef sand work? What should i use? I may be a few BBG in the future so i figure a sand like substrate would be good.
3. My final salinity should be 1.05 to 1.10 right?