NEPTUNE SYSTEMS DOS HEADCAP REPLACEMENT PUMP HEAD ESV Aquarium Products like this:

like this:

Pretty cool

but also because the leaking of air into a line would cause the pump not to meter the correct amounts

*Note* This is component #2 of a 2-part buffer system

An approximate setting of the water level is achieved by means of the water setting pipe

NEPTUNE SYSTEMS DOS HEADCAP REPLACEMENT PUMP HEAD ESV Aquarium Products like this:Direct OE replacement fluid metering head assembly for the Neptune DOS Fluid Metering System. The easy to install head replaces the tubing, roller, and plastic housing head cap. Installs in minutes Replaces wearable tubing The Neptune DOS Replacement Head assembly comes with everything to replace the current fluid metering head on your DOS system. Over time the self lubricating tubing will start to age, and can also cause excess resistance and