I hade this issue and soni got a new pump... sqme issue is happening.It shouldn't get air locked if its always submerged. I keep mine running 247. If I run it dry and fill the res it will, like you said, airlock. I just blow in the hose.
Otherwise it probably has a bad impeller, which can sometimes be replaced. Or you might need a new pump all together.
Hmm...Use a bigger bucket maybe?I hade this issue and soni got a new pump... sqme issue is happening.
Not sure how to keep it submerged... the end point of the drain pipe is lower than the pump bucket so it syphons all the water away. The pump entry sits so low in the bucket that the bucket is completely emptied by the syphon effect.
I put a non return valve coming off a t connector on the line... it breaks the syphon and stops water escaping. The end of the non return goes back jnto the top of the bucket just in case it leaks. Seems to work as the bucked doesn't completely emptyHmm...Use a bigger bucket maybe?
Sometimes the obvious choice is the right one lol.