Poor water pressure

Just installed a Water Fixer UV sterilizer/filter in the house water line immediately after the pump/dockwater connection. I really like the taste of the filtered water but the water pressure dropped significantly (oddly the drop in pressure is more noticeable when using the city water than when using the pump). The loss of pressure isn't too much of a problem in the sinks but I really miss it in the shower. I was wondering if installing a second water pump after the filter would bring the pressure back up? Any thoughts or suggestions?

Some filters/sterilizers need sufficient contact time to be affective, ie; a lower flow rate. I wouldn't be surprised that the system you installed has a maximum flow rate which is less than your system was before. By adding a second pump, if it does increase the flow rate, you may be decreasing the efficiency of the new system.

My filter system said expect a drop....reading many reviews on filter systems say many deliver way less than advertised flow rates.

Put the filter in the galley sink cold water supply only or install a filter water tap at a bar or other area. That way you only have reduced flow/pressure at one tap/faucet.

Your onboard water pump might put out more pressure than the dock water regulator valve will allow. What is the GPH rating on your filtration system? You might also try removing the flow restrictor from your shower head (if it has one).

You could install the filter in the dock hose and fill the tank with filtered water.

Is it possible to just bypass the filter for your shower? - Or just install the filter on the cold line to your sink(s).

Thank you, all good suggestions