New pump problem

Have an 18 ft AG pool. Had a 1 hp Jacuzzi pump and filter and a lomart skimmer. Pump went bad so changed to a New Hayward power flo matrix 1 hp pump that was new but got off of ebay.
Did add a 1 ½” PVC ball valve and elbow onto this pump to have a straighter run and to make it easy to clean strainer.
But with this new pump does not seem to have as much power. When I start to vacuum I have to put my hand over the return eyeball for a minute or two to get the pump sucking good. Almost like pump does not have as much suction or is a lot weaker. I do fill hose with water first and it will still have a problem if I don’t even put in vac hose but change the skimmer to just open the hole were the vac plugs in. Lomart skimmers have a separate hole for vac. Also lomart skimmers have a little smaller pipe opening that supplies pump so could maybe cause a pump to work harder to get its water?
+ Also checked and have no air leaks.
I thought I remembered that the Jacuzzi pumps were a little stronger when I bought my first pump 10 years ago. I would like to have plenty of suction and power.
So should I get another 1 hp Jacuzzi pump, or a 1 ½ hp Hayward or even go to 1 hp in ground pump.
Thanks for any suggestions

Also one other note. My auto vac sometimes flips over on its side with this pump about once an hour. Like it does not have as much suction to keep it stuck to the floor. I was thinking about an 1 hp inground pump. But a friend with the same setup has one and it maybe a little to much suction with the self priming since he had a little problem with it having to much suction was breaking out the bottom of his skimmer baskets. Dont know if a 1 1/2 hp pump would actually have more suction power or just can move more water.

Unfortunately you can't just go by hp when replacing pumps. It is all about flow and 2 different 1hp pumps can have drastically different flow rates. Add on top of that the marketing baloney of the max-rated/up-rated energy efficient pump which is just remarking a pump at a higher hp than it really is.

So you'd need to compare the performance data for the old pump to the Hayward data at http://www.haywardnet.com/abovegroun...ctID=121#three to see which pump comes closest to matching.