I use a generic form of seachems product here:
http://www.seachem.com/flourish-phosporus.php
Keep in mind it only takes a few drops a day to keep it detectable in 100 gallons of water volume, depending on how much you feed the fish. I feed in the evenings and dose P in the morning to keep it consistent. Also keep an eye on the nitrates as I've found dosing N reduces P and vice versa. It will most definitely increase the algae film on the glass even at levels around .015. When I started daily dosing my tank also went though another little "ugly stage" but the tank will mature another step as it did in the beginning. It will mature and go away like usual. The important thing is the health of the corals.
I have experienced health issues when one element is way out of wack in relationship to the other, referring to the redfield ratio. I don't think they need to be 16:1 but I try to keep both in relation somewhat. I wouldn't worry about nitrates of 10. One of my tanks runs really well between .75 and 5, while another I've increased from 25 to 35ish because the corals were looking too pale. Obviously there are other factors that come into play that I don't understand, but I see what I see. 25, No algae, or film, starving corals. The other can be 3, algae film all over.
I think maturity plays a big part. Even if you have top notch equipment and do everything correct (with patients) from the start, a tank started with dry rock is not mature at one year imho.