With bubble algae this rampant, it's likely your nitrates and phosphates will show acceptable, or near zero, results. This doesn't strike me as a nutrient issue and moreso an imbalance issue.
Bubble algae is a pain to deal with. I've shut down a tank in the past due to it overrunning my entire tank, including corals. I regret not tackling it with chemicals or something other than "in a tank that small, just do water changes". With that being said, that has to be one of the best looking torches I've ever seen. Your elegance looks pretty great too (not sure if the tentacles are longer normally). I would not recommend feeding coral foods, or anything other than what your fish need for now.
How did this tank start? Dry or live rock? Ocean direct sand? Or Dry/live sand? I'm quickly becoming a fan of Aqua Forest Lifesource (fiji mud/miracle mud). In my limited experience with it, it seems to have all the benefits of live rock, but ends up "coating" the rock and tank with bacteria and basalt that is super porous. I think at the stage your tank is at, it certainly can't hurt to try it out. Much more effective than seeding the tank with some live rubble and waiting for the good stuff to spread. Knowing what I know now, I'd go in with manual removal of the bubble algae heavy with a water change and dose the AF Lifesource after lights out that same day (turn off the skimmer if you have one) for a few hours after dosing).
If the life source does not improve the situation after a month or two, or if coral health is on the decline due to bubble algae growing on skeletons and choking them out, I'd go to the "hammer" solutions with a quarter dose of an algaecide product like algaefix (anything but Vibrant). I know this is unpopular, but if you're tossing the idea of rebooting the aquarium around it is certainly worth a try if the natural solutions aren't working. At the end of the day the tank should stay looking good and chemical treatments can be effective when used in moderation.
That bubble algae, and other nasty stuff, is feeding on the leftovers of your tank's food inputs. When you feed pay attention to where things settle. When you do your next water change and manually remove the bubble algae target those areas in the sand/rock. If you have room in your WC bucket left over, work on turning over your sand with the siphon hose. If you aren't blowing off your rockwork, pick a section and turkey baste the tar out of it and let your mechanical filtration grab it. You should swap out your mechanical filtration after water clears up.
I can't say this enough, those coral look incredible. You're obviously doing the majority of things right here. It's just the ugly bits that shadow those accomplishments. If you can get to the other side of this, the tank will be able to fend for itself for quite some time given routine maintenance. Wishing you all the best!
