I'm not sure what you were told to expect, but after only a week and a half (of doing anything) you're not going to see any difference in coralline growth.
The only thing that grows that quickly is stuff you DON'T want in your tank. LOL
When it comes to a successful SW
experience, patience is definitely a requirement.
As for Purple-up, aquarists either love it or hate it.
Personally it's worked well for me.
I used Purple-up in 1 of the 4 SW
tanks I have in the living room.
After 3 months that one tank had purple, pink, and green coralline completely covering the glass.
The other 3 tanks that didn't get dosed are only showing a few small spots of coralline on the glass.
As someone mentioned above, there really isn't anything in Purple-up that you can't get elsewhere.
Purple-up is just a combination of several things that you can get from PWC
, and that aquarists commonly dose such as, calcium, strontium, iodine, etc.
Of course, even tho I'm terrible about taking my own advice, if you're going to dose anything you should have a test kit for it to make sure you don't overdose.
Two other things to consider...
The color and growth of coralline also seems to be proportionate to lighting.
The stronger the light the better.
Also, the more coralline you start with in your tank to "seed" it the better.
Purple-up doesn't have any coralline in it to get you started.
Did you start with cured LR
that already had some nice colonies of coralline growing on it?
If not, go to you LFS
and buy a few small pieces of rubble that have some nice, mature growth of red and purple on them already.
BTW, coralline does not start off brown. That sounds like a diatom bloom which is normal for a new tank.
With coralline, you'll notice tiny spots of dark green, pink, red, or purple on your glass (where it doesn't get regularly scraped clean) that will slowly get bigger and spread over time.