I have the Hayward Acid Feed System AQL-Chem4-Acid. There is insufficient suction to pull acid from the hopper. I replaced the long plastic tube as it was cracked and the pump tube as well in the housing as it appeared worn. Still not enough to move acid up the tube and into the pool pipes. I tested without the long plastic tube on a bucket of water and the pump works just fine. Just not enough to travel up thelength of the plastic tube. Anyone else have this issue or any suggestions.