I'm the owner of an RSM 250, not the C-250. I had a chiller pump for quite some time but it stopped working. I've tried cleaning it, letting it pump in a bucket of water and vinegar, etc. None of this worked, so I figure it's at the end of it's lifespan. It was the RSM skimmer pump that I used for the chiller. (I'm using a Maxijet1200 now for the skimmer). I researched prices of the skimmer pump, which had fit perfectly in the right chamber. But these prices are extremely high, and I'm looking for a less expensive alternative for a new chiller pump. I have invested in a Mag 5, which, even with the stand removed, did not fit into the right chamber of the tank. I have since returned this pump, and my chiller is not connected to the tank. I only have a clownfish and cleanup crew in it, so I can afford to keep a rather short light cycle, so that the water doesn't heat up. I need quick suggestions for a pump, with a flow around 480 GPH, that will fit into this chamber without any mods to the tank or pump. I greatly appreciate any help that you can provide.