If you run a PhosBan Reactor 150 in your aquarium setup, this replacement O-ring is a must-have spare.

It's the rubber seal that keeps everything watertight so your filter media stays contained and your system doesn't leak.

Over time, O-rings can wear out, harden, or get pinched – and when they do, you'll notice drips or loss of pressure.

This is a genuine Two Little Fishies replacement, so it fits perfectly.

The reactor itself uses an upflow design that pushes water from the bottom through a dispersion plate for even flow and no channeling – but that seal is critical to keeping it all working right.

It's a simple rubber ring, but without it, the reactor won't hold pressure effectively.

Keep one on hand for when the old one gives out – it's a cheap part that saves you from buying a whole new reactor.

Fits the PhosBan 150 model and other compatible filter media reactors.