I've owned all the iterations mentioned here BK branded skimmers, Alpha made by RE and the Vertex Alpha, with all the included pumps. The pump heads and impellers are identical. I can't say on the internal changes reported to be made by askoll during manufacturing. As for the Anti lime line that runs from the pumphead to the block, I took one apart one time out of curiosity and found that line dead head into the resin of the pump. I know there is quite alot of D!*k measuring between the two companies, so i wouldn't expect representatives from either company to confirm any similarities apart from accusing the other of cloning. Both are great skimmers, but the pumps are damn close to the same no matter what way you cut it.
I’ve owned the Alphas and the Bubble Kings too. Infact, if you look at my history, you will see that I owned an Alpha 300 and have been helping Alpha owners long before I started working with Royal Exclusiv. I bought my Alpha 300 when they were first released. I’ve also owned a BK Mini 160 and other BK’s and now own a Supermarin 250 which I bought from Premium Aquatics. Royal Exclusiv made the Alphas for Vertex and included the RE made Red Dragon pumps with them (as you are aware) so yes, the pump heads and impellers were the same. Key word being were. They no longer make the skimmers for Vertex nor do they build the pumps for the Vertex Alphas anymore as you are also aware of. The pumps volutes and impellers are now made “elsewhere” but yes, they are still very similar and the untrained eye wouldn’t know the difference unless you had the two pumps side by side and even then, the differences are subtle.
As for the AKB, you are absolutely, positively, without a shadow of a doubt mistaken. I’ve taken enough apart myself and having owned bubble kings long before I got involved with Royal to know better. I also handle support for RE but I also have no reason to lie. The AKB goes into the magnet cavity and sends water from the pressure side across the magnet. On the Small Block Askoll motors, it goes into the back of the block behind the bearing and on the big block Askolls, it goes in through the side of the block. The ONLY way to verify that would be to look into the small block from the magnet cavity to see the small hole behind the bearing and on the big blocks you would need a small mirror that you could slip into the magnet cavity to see the hole where the pressure side goes into the block behind and below white sleeve. That or you would have to break the AKB connection off from the outside. Either way, I can assure you, it’s not smoke and mirrors and it does serve a purpose. It was also NEVER included on the Red Dragon 1500’s that were included with the Alphas. I can’t speak of the Red Dragon motors that had the Pro Line Aquatics label as I personally have no idea whether Proline sourced those motors from RE or directly from Askoll as that was before my time. Beyond that, you are correct, the pumps are “damn similar”. There are some minor differences in the motors themselves as delivered by Askoll that differentiate themselves from the standard Askolls and then some minor differences between the volutes on the Royal Exclsuiv made Red Dragons vs the now Vertex made skimmer pumps that use Askoll based motors.
Also keep in mind that I’ve have helped countless Vertex Alpha owners over the years and even the current Alpha owners who buy the latest Alphas that happen to be on this forum as well as those elsewhere frequently come to me for help with the Vertex made Alphas because I know those skimmers inside and out. RE also gets calls and emails on them. Then there is the fact that many people think that RE still makes them for Vertex so inadvertently, we often become the first to receive the support inquires whether it’s in warranty or out of warranty problem. As such, I am intimately familiar with the differences between not only the pumps but also the bodies. And for the record, I have nothing against Vertex. I own some Vertex equipement myself. Heck, I even bought into the Cerebra to see what all the hype was about. I am also a fan of ANY Askoll based pump whether it’s made by Vertex, ATB, Fluval etc. Infact, I recommend Fluval pumps all the time here and elsewhere because it’s uses one of the best AC based blocks of it’s type (Askoll) and makes for a great pump regardless of whose label or volute is on it.