First, the materials they use simply shouldn't dissolve when they are used for purposes clearly spelled out in their flyers. They specifically say it will handle concentrated HCl...the pump does, but the nuts that hold the hoses in place don't, they melt. They say the self-priming height is 5 feet, it's about a foot, maybe a little more. If the pump loses prime, you have to lift the bucket up to the height of the pump to get it to prime. The darn thing has a serious tendency to leak. The way the fittings screw into the pump head doesn't allow the O ring to compress well and great care has to be taken to make sure it seals.
But the thing that ruined the previous set of fittings is the simple nipple that holds the tubing to the pump head. This is what it looks like.