Sera Union nut for 130/130+UV E

A union nut for the hose connectors of the sera fil bioactive 130 and 130 + UV external filters.

What the part does: the nut clamps the hose tightly onto the filter's connector. It is the part that holds the joint together under pressure – without it the hose comes off in use and the aquarium empties onto the floor.

When to replace it: when the thread has worn, the nut has cracked, or it no longer tightens to a seal. An old plastic nut typically breaks just as it is being tightened, so the fault turns up during maintenance.

Check the model: this nut is for the smallest models of the range, the 130 and 130 + UV. The 250, 250 + UV and 400 + UV have a nut of their own.