Calcium reactor location

[duke62]

no charlie he is coming to me first LOL.im fraking confused.there is only 2 lines one from eheim and 1 for CO2 i must be missing something.

 

[Long-Island-Mike]

Its a circulation pump.. which means it keeps the water in the reactor circulating in itself (mixing to make the co2 and media well mixed), but you still need a feed pump to push water into the reactor, and from that pressure, there will be some water exiting the reactor into your sump for dosing.
I would suggest to just T it off from your return pump so you don't need to add another pump, and a return pump is usually stronger so will be less issues with the pump clogging or too much pressure for the pump to handle if you have a valve installed after the T

+1, its a circulation pump. You still need the feed pump. I used a maxi jet in my sump for my feed pump with a little adjustable drip valve back into the sump from the reactor.