I see a few things that need/could be addressed. By the look of the Calaustrea aka candy cane, my first guesses would be either a phospate or magnesium issue, and or just as commonly both compounded. When giving perameters on an established system ammonia and nitrite are really not needed. If it was under 3 months old these measurements are very usefull, but moreso just to tell you the stage of cycle it's in. Nitrate on the other hand is usefull as it can be a reflection of the bioload and also an insight to how well your tank processes the traces of ammonia and nitrite it encounters which should be miniscule.
I noticed no Mg measurement, great tool to ensure that your dialed in for a healthy trifecta(Ca, dkH, and Mg) for calcification.
Another note, dont trust your phosphate test! It will only show you measurements suspended in the water column, NOT which is bound to algaes, which no offense, is clearly an issue. Noting that micro and macro algaes take in phosphates to grow and the fact that they
are growing should tell you that indeed phosphates are in the system, which is one of the major inhibitors to the calcification process to all corals which we as a collective are in constant battle with as hobbyists, that along with Nitrates are the major 2 evils
Phosphates can be managed successfully with some form of granular ferric iron hydroxide( or GFO) whether its named rowaphos, phosban, etc. Unless you have a super uber skimmer, or a refugium bigger than your tank you may want to consider GFO as an export alternative.
Another point, not so much particulary for the candy cane, as the one you have does fine under low light, but overall your corals would highly benefit from having more intense lighting. Thier health/vigor/ and coloration would increase exponentially.
And from someone who has had 10X more bubble algae then I see in that photo, manual removal is the best. Unless you have a miracle foxface or other algae eater that would be more than likely to big for your sized tank. And try your best not to rupture the bubbles, which sometimes is virtually impossible. After a major removal session and with rumors of that algae carrying spores I like to follow the pick and pull with a large water change. This will help reduce the spores if any released into the water column as well as any detritus that Ive stirred up in the process. All this has cut my bubble count by, Id say, around 70% or so. But it is an ongoing process, and the work of the hobbyist is never done, right?
Good luck!
-Justin