Clogged booster pump return line

My booster pump is drawing water from the pool, but my sweeper won't run when I turn it on. I pulled the sweeper vacuum out of the pool while I had the booster pump on, and it behaved as though it were turned off. I checked the pipe from the intake line, and the pressure is just fine. But when I plug it back into the return line, nothing! So I have to assume there is a clog in the return line somewhere. Is it safe to put a garden hose bladder in the return line to try to clear it and blow it out? Thanks in advance.

Some pressure-side cleaners are designed to shut off water flow if you pull them out of the pool (keeps the pool from getting accidentally drained). You should disconnect the cleaner from the wall port where the booster pump pushes water out of. With the wall port open, see if you can feel a high flow of water from the port. If not, then there's a definite problem.

I would be surprised if the booster was running normally with a fully clogged line. Typically if a pump is dead-headed on the pressure side it will make a horrible noise. A partial clog could allow the booster to sound normal but restrict the water flow enough that the pressure cleaner can't run.

If you do have a partial clog, you can certainly use a garden hose and FlowKing (hose bladder) to try to push the clog out. The only problem I find with that approach is that house water pressure from a spigot is fairly low pressure unless your connection is right at the main going into the house. But certainly give it a try.