ya I know but its was to big for my setup so im hoping that this skimmer is going to keep up since I'm running Acans Blasto's , Micromusso's, a few leathers a huge clam, lobo's too and a lots of fish like 21 in the 150 gal
That's somewhat of a small volume / bioload for the Alpha 250, however you should still be able to get it work, and to not overflow. My first guess is that the overflowing is due to varying sump level. Also, 8" is too shallow for the Alpha 250. I would highly recommend running at 9" - 9.5", and with a very light load maybe even 10". Take a look at these couple of tricks, as well as installing the 47mm (shortest nozzle) for maximum air draw.
Did your skimmer come with a 47mm, or a 56mm and 59mm?
how do you keep the nitrate down w/ that many fish.
I think the 170 is the better fit for your size system in my opinion. The 170 will handle even more than what you have actually. Are you still running the skimmer at 8"?
should go away after 2 weeks or some, it all depends on your system how fast the skimmer will slime up