I will let someone else describe your problem here, but my thinking is that the pump you have isn't made to create "pressure" but instead its purpose is to move large volumes of water. You probably need a different type of pump

It's the back-pressure of the water in the manifold that makes it stop working. You need a different pump or a re-designed system. If your reservoir were taller, you could have a higher water level and make the pump not have to push water so far upward.

The pump wants to move more water and you are restricting it too much. I've had this same problem. Try putting a tee in the line a few inches above where the pump hooks up underneath the waterline. Allow the tee to split the water with half going to the system/drip lines and the other half going directly back into the reservoir. This will allow that pump to move more water like it wants and you should get better pressure plus your nutrients/water will get mixed well. Another alternative is to have the end of the 1/2" manifold loop back into the reservoir instead of dead ending. Mine was not continuous drip, but ran a few min each hour.

Thanks for the advice and explanation. I will add a tee and let you know the results.

make sure you have a valve on one of the T lines so you can adjust the flow.

Hello. Did you add the t line? If so, did it work?

You definitely need another type of water pump, it can be strong sump pump, for example.