Not my picture but the area I circled, is it okay to have your manifold that’s on a separate pump dead end like this? I will have a UV light, reactor and the last one will be for water changes
You will lose a bit of head pressure, but it will still work fine - as long as you have some reduncancy built in for the pump (ie. you have upsided it and not needing to run it at 100%)
If you have water running thru it constantly it is fine. If not turn off the pump and open the valves, other wise you may have some unwanted bacterial growing in there. If that is your question.