Hi,No luck my friend. How much of the HP would you put? I put around 100ml in my sink which has all my rocks and as it cooled down I could not wash the algae out :/
As I previously said I've not tried it myself for this specific task but I would've mixed approximately 2.5l of 3% (perhaps even stronger as it is not being used in the presence of livestock) H2O2 with 20l of water into a 25l tub and left it to soak for a week or so. I'm not sure how much water your sink holds but your mixture sounds to me rather weak, and I'm also unclear what you mean by 'as it cooled down'. H2O2 is used notoriously in the battle with BBA.
I'm sorry what you have done has not satisfactorily worked out for you but the only other options I can think of are either a Glutaraldehyde or bleach soaking.
Good luck and keep us posted.