The two best additives, aside from Hydrogen Peroxide, are Hydrogaurd and Hygrozime. The first is a bacterial anoculant, the second is an enzyme product (the best on the market). The hydrogaurd is simply a set of aerobic bacteria that displace harmful bacteria and fungus, despite this it will survive hydrogen peroxide as it thrives on oxygen. The hygrozime is the only enzyme product that is sterile, that is it does not have the risk of adding unwanted bacteria that can really mess up your system. It has the added benefit of taking any dead plant matter and breaking it down into compounds that can be used by the plant. In other words, if root rot, even on a microscopic scale, starts, this will remove the material that would breed massive amounts of bad bacteria and fungus and prevent it from spreading... However it is rather expensive, but it's worth VERY penny! The hydrogaurd is cheap shit so thats good. Other then that, keep the temp cool and you will have no issues.