No, I don't have seahorse tank setup yet. I only have an extra 20g tank and want to plug it into my current 200g system (if the cost to maintain it is not too high )
If I have to do it, I will remove the "tee" from the return pump to the frag tank. Let the main tank take full force from the return pump.
The main 144g tank then drains to the frag tank. From the frag tank, the water will over flow to the sump.