The crushed coral is the best PH stabilizer there is in my opinion. I put the coral in a mesh bag and stick it in the filters and my PH is always 7.2. Now 3 years ago before i did this every once in a while one of my tanks would go really acidic out of no where!! One time I lost a fish that I really cared about due to one of these PH drops. But since I have used the coral there has NEVER been a PH change. If you need to cycle faster, and you don't have any other sources for used filter media, just ask your LFS if they are about to change any of their filters and ask to take the old used filter. Just MAKE SURE its a healthy tank you are getting this filter from cause you don't wanna introduce disease.