I think I understand the pump you're describing. I can only guess, but I think you will find it too small to be very effective.

Additionally, to be an effective vacuum, you must have a way to filter the water before returning it to the pool. I'm not sure you have allowed for that. Is there a way you can install a larger pump, capable of vacuuming, to your existing system? That way, you can filter the water, too which is a must.