Glass Lily Pipes and Inlet Outlet Guide

Glass lily pipes are the detail that separates a tidy aquascape from one cluttered with black plastic. They replace the bulky intake and return of a canister filter with clear glass that all but vanishes against the water, but they change how the water moves as well as how the tank looks.

Inflow and Outflow: Two Different Jobs

A lily pipe set has two parts. The inflow is the intake, usually fitted with a slotted strainer that stops fish, shrimp, and leaves being pulled into the canister. The outflow is the return, and its shape is what earns the name: the flared lily or the P-shaped violet outflow spreads the returning water along the surface rather than firing it in a jet. Point the outflow across the top of the water and it creates a gentle, even ripple that circulates flow through the whole tank.

Getting the Surface Ripple Right

That surface ripple is the whole point on a planted tank. Enough movement keeps oxygen up overnight and prevents an oily surface film, while too much drives off CO2 on an injected tank. Adjust the outflow's height and angle until the surface shows a soft, steady ripple rather than a churning boil. Sitting the outflow just at or slightly below the waterline usually gives the cleanest result.

Living With Glass

The trade-off for the looks is fragility. Lily pipes are thin borosilicate glass and crack easily if forced onto stiff tubing or knocked against the rim, so warm the hose in hot water before fitting and handle them with care during cleaning. Suction cups hold them to the glass; check them occasionally, since a pipe that slips can splash or drain water over the edge.

The Bottom Line

Fit the strainer intake at one end and angle the flared outflow along the surface at the other, tune it to a soft ripple that keeps oxygen up without gassing off your CO2, and clean the glass regularly. The reward is filtration you stop noticing and a surface that moves just enough.