The SCA 303 came with an Atman PH2500. I believe Atman has gone out of business. You might want to see if you can still find an Atman or check with SCA to see if they have identified a new pump (and most likely an "ungrade" kit.) I know Bubble Magus has identified a new pump to replace the Atmans for their NAC6, NAC9, NAC66, NAC77, NAC3+ and NAC3.5. However, you do need to purchase an "upgrade" kit for between $70 and $130. I'm stuck with an SWC 160 that also uses an Atman....and SWC has done nothing to find a replacement.