The problem with(off topic) cleaning rocks with peroxide, the algae grows back... Yes, I too went through the process and even farther(changed the sand and 90% of the water). But slowly changing the enviroment is longer lasting and healthier for the inhabitants. I, added three lava rock columns and three 8" deep sand beds containers into the sump. After three months of heavy growth, the algae appears to be receding. However, there is no scientific proof that anything I've done has had any effect, other then the assumptions I infer.