Air in freshwater system

[RonNP]

I use a Headhunter pump for pressurizing my fresh water system. Over the past month when my fresh water tanks are about 1/2 full the pump seems to suck in air. I've tightened all of the visible hose clamps I can find connected to the water tanks. My next step is to disconnect the pipe from the tank and see it has cracked inside the tank. I'm assuming that the pipe goes all the way to the bottom of the water tank and sucks water from there but I could be wrong. My suspicion is that I may have a hair line crack in the suction pipe. I have two water tanks. The one in the aft lazertte drains into the main tank just aft of the engine room.
Any suggestions?

 

[Pascal]

Which headhunter ? Mach 5? They can be tricky to purge Instructions are on the HH website.

You need to fill the tanks, open 3 or 4 faucets, and turn on the pump. As pressure builds, turn off the pump for 15-20 seconds then turn it on again. Repeat 6 or 7 times then turn the faucets off

Everytime i ve had issues, like if the pump had run dry, this is what I ve done and it fixed it.

 

[RonNP]

Yes it's a Headhunter Mach 5. I've purged them and they are great until the tanks get halfway low. Full water tanks I'm great.