Parameters please help me understand

[PhishFriends]

My tank (50g) has been running roughly a year. I've had my parameters stable at what they are for nearly the whole time. This tank was a transfer from a smaller tank that had the same parameter characteristics. Mg, Ca, and Alk have always been high, and I've done ICP tests that correlate with my results. PO4 is tough to keep up but I feed pellets and that usually helps. I dose Sodium Nitrate. Here's the numbers; (Salifert)
Alk - 9.5 (pH - 8.1)
Mg - 1650
Ca - 530
NO3 - 10ppm
PO4 - .03ppm (Hanna ppm checker)

The reasons for this post:
1. Why won't Coralline grow? If they like the same conditions as sps, then I want those conditions. My Radion Xr- 15 is set to 65% max over 11 hrs. I've seeded the tank, and have frags and snails encrusted.
2. Why won't my Ca, Mg and alkalinity drop if I'm not dosing them at all. Using reef crystals and keeping salinity at 35. Montis grow, LPS grow fine. I had one Stylo that went white, but my green birdsnet is growing VERY slowly and has never had the plump polyps I bought it with 6 months ago.
3. Lastly a developing algae issue. I can easily let me nitrate and phosphate go down and wipe it out, but I've been working on stability. I didn't have the issue when I kept nitrates at 5ppm, but started to see some cyano developing. At my LFS's advice I brought my nitrates up a bit. I also added phyto and an Oxydator.
Long post, but I've been thinking on this for too long without any resolution!

 

[PhishFriends]

I know your all smarter than me.

 

[Cool Fish]

Might want to check your flow.
Also, the Bird's Nest can be tricky. If you have a Yellow Bird's Nest (that looks green) is needs lower light, but higher flow. If you have a Green Bird's Nest, higher for both. But, if it's growing, give it some time.
Also, why not lower the ALK and CA dosage just a tad?
I would also be patient for the Coralline. It will come.

 

[Dbichler]

From zooming in on your snails it doesn’t look like they have much or any. I would buy a small rubble rock that is covered with it and scrape the you know what out of it in the tank and it will spread.