Questions about loud brand new pumps

[hrdneglcry]

I replaced two PSK 2500s on a SWC250 Skimmer. From the old broken pumps I swapped the bottom collars which were fitted with venturi nozzles. The old pumps had needle wheel impellers. The new ones do not. My other skimmer runs just fine with a Rio 2500, regular impeller and venturi valve. But these PSK 2500s are very loud when I try to run them how the originals were run. Also no micro bubbles. If I pull the tubes out and the fittings for the venturi tube the pumps are silent. But obviously no bubbles without venturi. What am I doing wrong? This system ran like this without being loud. Now with brand new pumps I am not able to yet get it going.

 

[blaxsun]

Can you post an image with the different nozzles/impellers?

 

[hrdneglcry]

Not sure. I can pull that tube off and the plastic fitting. Then the pump is silent. Runs silent. But I meed a venturi to power the skimmer. The pump is identical to the old one except for the venturi. Also I think the impeller in the old has needlewheel top and new one os standard.

 

[blaxsun]

Can you just swap the impellers?

 

[hrdneglcry]

idk i don't have of the pumps. i might have to order pinwheel impellers

 

[hrdneglcry]

OK I wanted to start a new thread but its the same subject. I bought two new psk2500 to run an SWC 250 skimmer. One of the old pumps was seized and the the other had a hard time starting. They were PSK2500s also. Mine were retrofitted for venturi. So all I did was swap the bottom collars which were modified for venturi tubes. But the new pumps won't make microbubbles. Is it because the new pumps are not neddlewheel? I am hesitant to mess with them because they are new. I have one needle impeller that might work. Could that be the reason that it isn't making bubbles and that it is loud?