Pump Cavitation

[der_wille_zur_macht]

Most big box store ball valves are compact - the ball is smaller to make the entire assembly smaller. If you look through the valve when it's open you'll see it necks down pretty significantly. Then, go pick up a full-flow ball valve of the same nominal size, and the inside diameter when closed will be the same as the ID of the pipe it's meant to mate with, so there's no restriction.

If you can't find full flow valves you can always use a bushing to go up a size. But it's debatable after a point if it makes a huge difference. If you've got a 1.25" fitting on the pump I'd just go up to 1.5" and use the nicest valve you can find - if all you can get is compact, no big deal as you're already 1/4" over the fitting size. But like I mentioned above, most Lowes stores have a nice single union 1.5" BV. They only carry this model in 1.5" as far as I've seen so it's an oddity but I'm happy to take advantage, as it's like $9 which is cheaper than the junky compact BVs they sell (and you get the built in union!).

 

[AmherstReef]

Ok I got it now, definitely going to make a few upsize changes and see what happens

 

[captain7359]

How big are the bubbles and are they continuous when the pump is full bore? It looks like the skimmer and center sump chamber is full of microbubbles from the pict compared to the clear fuge section. 1500 gph is a lot of flow for a 40 gallon sump, so you may have more bubble carryover than you think and they are more visible in the bright display tank than in the relatively dimly lit sump.

 

[AmherstReef]

That's an old picture just after finishing the new sump, there are no microbubbles in the sump, only in the tank when the outlet is open all the way

 

[AmherstReef]

Redid a few suspect fittings on the inlet side , opened the outlet full and 90% of the microbubbles are gone. Figure if I upsize the inlet plumbing and remove the union that may help as well.