Easier Manifold design?

[Starling541]

Never seen this style of manifold in an aquarium. Is there a reason why this manifold with cold slip fittings off the 1/2” sides, a gate valve on the 1” entry and two 1” unions on the entry and exit would cause issues with a saltwater return line?

 

[fryman]

On the return line it will have little back pressure and so flow through the 1/2" lines will be very low. Perhaps could work depending on the use case but if you are planning to run something like reactors on those it won't work well.