Suppose it would work if it had actual coraline in it. I would recommend just buying a nice peice of live rock covered with coraline.
Turn off your filter and skimmer, scrape off coraline from the rock and allow powerhead to flow it around the tank. Once it settles turn on filters and skimmer. Wait few weeks they should start to grow.
I beleive you can add calcium and this will help the algae grow(Not positive on this).
+1. The scraping/seeding technique has worked well for me in the past. AFAIK, "purple up" is primarily an iodine supplement which really isn't necessary (if you do regular water changes) and can backfire fueling bad algae.
There is absolutely no need to add a special potion to your tank to grow coralline algae. I find it grows fastest in moderate light and moderate to high flow. If you drip kalkwasser or use some other means to maintain your calcium and alkalinity levels at natural levels it will grow like mad.
I've used purple up. It does work but a lot of the new coraline algae it grew bleached when I stopped adding it. I got more consistent, non-bleaching coraline algae growth with kalkwasser drip. I use Kent Marine's brand.
In addition, it is possible to grow coraline algae without the best light and water parameters. Coraline algae comes in multiple colors as you know but it also comes with different light requirements depending on the species. Bright light, will actually cause some species to bleach. If you're going to seed the tank, consider buying rock with coraline algae growing under similar lights that you have in your tank.
That's my two cents on it anyway.