Unfortunately we do not have a time frame on them. It seems they go out as soon as they get in the door, and they just can not supply us with enough quantity on them.
A lot of people have been taking the Coralife ozone reactor and turning it into a Phosban reactor. It is actually from the same mold as the Phosban Reactor, and takes about 5 mins to turn it into the fluidized filter.