Hikari® Aquarium Solutions® AccuProbe™ Hydrometer Bulk Pro-Series Check Valve Assemblies are

Pro-Series Check Valve Assemblies are used inside Pro-Series skimmers to bring the flow of water from the pump up to the outlet hole in the back wall of the skimmer

5" MPT to 2" SLIP

and it will bond to liner

7 @ 8400gph @ 9' A2-11/2-HH 1-1/2 208-230* 1900 / 8

That would translate to 13 to 32 liters of air per minute per foot of tubing

Hikari® Aquarium Solutions® AccuProbe™ Hydrometer Bulk Pro-Series Check Valve Assemblies areThe Hikari Aquarium Solutions AccuProbe Hydrometer measures a wide range of specific gravity and is intended for marine aquarium use. "Dry hands" design avoids contamination of aquarium Measures a water sample at 6" depth to avoid inaccurate surface sampling Accurate to 0. 001 specific gravity and salinity Designed to give a temperature corrected reading in warm water aquariums Durable construction for extended life Includes self leveling hanging