Beware H2o2 (Hydrogen peroxide) is stabilized with Tin which like Copper is a toxin to our friends here
Justin Credabel gave a presentation at MACNA 2014 about H2o2 dipping. He labeled it as good for Algae, Brown Jelly, Bacterial infections, flatworms, polyclads and as a general QT dip. The threshold of corals varies greatly but he has some public dosing tables on manhattan reefs under the topic name '
Any Questions about Peroxide dosing or dipping?'. I have personally dipped some corals in H2o2 dilutions with no ill-effects so far mostly on Caulastrea diluted at 50ml (h2o2 @ 3%) : 1000ml h2o for 5 minutes.
When it comes to destroying algae nothing beats Hydrogen Peroxide. I have a Zoa rock that was being overtaken by some very strong algae that not even the crabs will eat. When attempting to remove it from the rock it literally would have rock come with it. I removed the rock from the tank placing it into a large tray and got a pitcher of tank water. I directly applied 3% h2o2 to the trouble tuff of algae and then pour tank water on the Zoa's around the treated area.. I'll likely have to do it again, but as you can see from this bad photo its clearly killing this problem algae. I didn't lose any of the red Zoa's next to the treatment area.
Zoa rock with Alage Tuff
Zoomed Photo of Treatment Area
Here is his YouTube Presentation:
https://youtu.be/fmeoPS09Lx8?t=14m16s
For anyone curious there also are some studies with H2O2 and Cyno called 'Combined Exposure to Hydrogen Peroxide and LightSelective Effects on Cyanobacteria, Green Algae, and Diatoms' :
http://pubs.acs.org/doi/pdf/10.1021/es060746i