Nope.
Scenario:
I have 2 return pumps in my sump. The big one returns to the main tank. A smaller one, the Dolphin DP560, returns to the goby tank. The DP560 has 3/4 fittings at 560gph.
Formerly, I have my 3/4" chiller inline with the return pump:
SUMP -> DP560 -> chiller -> goby tank -> overflow -> SUMP
So the pump runs all the time; it just happens to go through the chiller. The chiller was on a temp controller to kick on it's compressor as needed.
The DP560 will blow this chiller away, especially if I throttle the pump down to 1/2" tubing. If I "T" the fitting, I lose a ton of head. If I simply "Y" the fitting, I can't control the flow to the chiller and I still need to reduce the tubing. So far the only thing I have come up with is:
pump ---> 3/4 tubing ---> "Y" ---> valve ---> reducer to 1/2" --- >chiller --- >sump
(from the other "Y") ---> valve ---> goby tank ---> overflow ---> sump
That's nasty.