Dont think u can totally remove valonia in your tank they can survive in ultra low nutrient water too and the only way is to control the qty ... best fish to eat valonia still sailfin tang (Desjardini only will eat valonia and not veliferum ) . emerald crab just hit or miss depend on luck and they dont move around whole tank ... off cause when fish eating the bubble algae will spread whole tank but if the fish continue feeding on it than u wont see any in your tank unless those area that the fish can not reach ...
yes thats y this doesn't look like Onyx (Percula) should be a tank breed black photon (Ocellaris) ... even black photon is a cross breed but still consider as ocellaris
Prazi Gold is safe for SPS , zoa and anemone ... I have dose to remove my coraline algae before and follow recommended dosage twice (dose 2nd time after a week) and all sps, zoa and anemone (I only have magnifica anemone) not affected ... but skimmer will overflow crazily ...
me also thinking of ulcer too at beginning have try yellow powder and others antibiotic and melafix too but didn't help ... wc solve my problem ... do it early before it become more seriously , or will have a lot of big hole on body after recover like HLLE ...
me have this problem before but only happen on vlamingi and spotted unicorn ... tested some medication but didn't help , but just daily wc about 10% after more than a week fully recover ...