I don't think I trust the stick-on's either.. and I had a digital one a while back but the probe went haywire and that was that. I'll probably just stick with what works and do the maintenance.. the only thing I was concerned about was if the coralline somehow affected the accuracy since it's covering the bulb.
As for encouraging the growth, I just maintained good conditions and it eventually started by itself. I don't dose anything regularly yet.. just the occasional 2 part when needed.
I did notice a snowball effect after letting a powerhead scatter some scrapings.