Need some help with Whisper impellers

[fishbone]

I have a HOB Tetra Whisper PF 30 and PF 40. They use the same size impeller.
I am trying to source some cheap replacement impellers as they get noisy over time. The problem is, online, they are labeled in anything but comprehensive ways and can't tell which fits what.
I've noticed they are color coded, some are blue and some are white.
Are all blue ones the same size?

[lohachata]

have you tried www.drsfostersmith.com ?

check their parts section.

usually within the same manufacturer the same color parts would be the same size.

[fishbone]

I just did and their naming is somewhat more straight-forward.
Fairly confident I picked out what I need based on Tetra part # quoted in their catalog too.
Thanks for the suggestion!