25 for the phosban reactor. I am looking for a hundred for the uv sterilizer. the uv sterilizer worked awesome u just need to slow down the water flow through it to get a full effect. It did work I stopped using it when I was deciding whether or not to go zeo. In total all three ( phosban reactor, denitrator, and uv sterilizer were used for a year or less) are in great shape. I only used the uv sterilizer for 8 months. The denitrator I have is made for a tank i think 55-75. I used it on a 190 gal system and worked marvelously.