There should be a flow restrictor in the waste water line the vertex one is a small clear plastic piece that fits inside the 1/4 inch water line and its easily lost.
With out it you will have tons of flow out the drain line. Only other issue I had was bad to membrane but I issume u changed yours .
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360 gallon sps reef, 180 gal sump, bubble king supermarine 300, 4xmp40Wes, 2 x 6215 tunze waveboxes, 4 ghl mitras
360 Reef Tank