Excellent
That algae isn't due to poor nutrients it's associated with new tanks lacking coralline and algae/diatom rejecting living mass
Your number two cause of that growth paired with the non calcification of surfaces is too much white lighting vs blue, so depending on lighting control you can begin to ease it's growth and guide in the preferential ones over time if you blue it up
In the meantime you have instant control over the growth so that other communities don't begin to mix in... hair algae is next coming due to exact same reasons. You can lift out any rock you want, pour peroxide across it outside of tank, let sit a couple minutes cooking, rinse, put back and it will die off.
The hand guiding stops over time independent of nutrients because of the early hand guiding until calcifications do the rejections full time
For sure adding GFo and other stasis changes to the system can shock it gone, but you'll find the hand guiding quick, lasting and easy/fast
Simply disallow the growth by direct physical action, it's the secret key to nano success long term. My own nano is one gallon and ten years old and all purple with coralline due to early hand guiding which I haven't had to do since 2007. I don't know what my nutrients are because I own zero water parameter test kits. My friend John Cole tested my water and we found the phosphates a bit high, but it has no impact on anything my reef was immune to all invasions since 07
Lastly, if your new sandbed was unrinsed from the start this can contribute due to find particle silicates being utilized until again they become coated in bio-rejecting films/scums it will all settle down
This phase is not your test phase, the GHA of next month is, do this:
http://reef2reef.com/threads/5-new-...be-cured-using-a-rasp-and-a-test-rock.257862/
The number one trick to getting ten years out of a nano reef is that, above anything you could ever install, purchase, or connect or dose