ok

we can do some in tank work then I just like to offer what gets the fastest outcome first. the in tanks are by far the largest percentage of treatments on this thread, heres another.
I didnt see cleaner shrimp, they and anemones might die. not sps, Ive never seen any that will die in the way we are about to treat and your tank will be another testament. promise you'll do follow up pics along the way!! back a few pages ago we had some -really- nice pre treatment pics that kinda left us hanging.
heres the right way for your setup
find something to inject with, like a diabetics syrings from a pharmacy. convince them you arent a meth head
take this in spots, not all at once. at no time do you just pour the peroxide in the tank even though that does work. since we are doing in tank work, full, there is still an amplification technique we should do. the underwater spot injections from previous pages, try to read it all if you get a chance tonite just to get any extra ideas like the saran wrap version etc.
basically all we are doing is turning off pumps, letting water still so the peroxide will stay as long as possible (brief seconds) around the target before dissipating into the water
so you would remove and externally treat what you can without hand removing the algae. this is to gauge the grow back and the expected time frames for kill for the underwater treated areas. remove, apply and rinse and put rocks back in and lets see through pics what the dying algae looks like and how long it takes to fall off. we use that to work our underwater option on the rest of the tank, with the expected timelines known
for the parts you cant remove, take a few mil's of peroxide, cc's if using a syringe, and while pumps are off and things are still, start injecting around the base growth areas of a certain rock. inject very very slowly, as it leaves the needle the peroxide is in high concentration in the water around your algea tufts, this is killing it. the rest of the peroxide just drifts off into the tank.
there isnt a certain dosage, sps are tough to it, but you will always use just a few cc's per day in a few areas, watch to see how those sps do in the next two days before moving on and injecting.
at least up your normal water changes during this run, something will have to be done above normal to make up for allowing this much of a tankwide infestation but agreed we can work without a full drain. peroxide is caustic but not lethal in your setup, so these water changes reduce causticity.
remove and treat what you can, post follow up pics as the algae is dying so we can see it and learn what to expect. for the underwater areas, do one section at a time, taking weeks to complete we can't be in a big hurry. this took some time to become eutrophic, and it will take less but still -some- time to return the tank to oligotrophic conditions. Im assuming your nutrients are kept in order this whole time....but a recurring theme in this thread shows that even with that, some zapping is required in the majority of systems!