we have done hundreds of bubble algae treatments in the link in my sig (which links to other threads too) and this is my take on perox+ valonia
in tank dosing is not the right way, too few success rates. Where it shines is the external treatment, for sure it will bleach out ghost white and die. if you can remove rocks, you actually scrub off the valonia before treating and rinse the area totally, so that the infected area is now bare and you haven't even dosed yet. the rinse is carrying away what bits it can...then you hit the bare spot with peroxide to hit the missed regenerative bits, and any holdfasts left in the rock which are the regrowth potential/
the spore aspect of valonia is grossly overstated, that's only a small reproductive window where its sporulated. 90% of the time its a water vacuole with chlorophyll and various inclusions, the actual plant wall and mass is your reproductive risk, fragmentation just like GHA
external treatments are the only good use of peroxide here, although tankwide dosings have random reported success.