If you have a saltwater fish tank, then the protein skimmer is a thing you cannot skip. The best in sump protein skimmer will operate in a sump, hidden from view and work for reducing phosphates and nitrates, increasing oxygen concentration, maintaining proper water PH level, etc.
This post below is the comparison between the two best protein skimmers that may help you get the right one for your tank: SCA-302 180 Gallon Protein Skimmer vs Bubble Magus BM-Curve 5 Protein Skimmer.
#1 Aquarium size
It is obvious that you have to choose a protein in sump skimmer with the capacity that suitable for your tank size. Make sure that the skimmer can handle the volume of your tank.
The Bubble Magus BM-Curve 5 is rated to use for aquariums that hold up to 140 gallons of water. It includes a high performance SP1000 pump (22W – 120 V/60 Hz) with a venturi intake, which produces a huge amount of air bubbles in its reaction chamber. This is what makes Bubble Magus BM-Curve 5 a great value.
SCA-302 is a powerful skimmer that is a perfect investment for saltwater aquariums up to 180 gallons. It features a good power pump (700 GPH, 41 watts – 110 – 120 V/60 Hz).
#2 The skimmer size
Since you are looking for the in sump skimmer, so this device will not take the space inside your tank and also not seriously affects the aesthetics of the aquarium. But you have to consider the sump in the cabinet under your tank. Make sure that the skimmer you choose fits with the sump in the cabinet you have.
Bubble Magus BM-Curve 5 is quite compact in size, it measures 26W x 9H x 10L inches, which make it fit with most sump cabinet. While SCA-302 measure 9W x 18H x 9.5L inches, you will have to consider if your sump high enough to place this skimmer.
The Bubble Magus BM-Curve 5 includes a bubble plate that acts for reducing the turbulence in the reaction chamber for a spin out the time to connect between the bubbles and the organic waste in aquarium water. Due to this, BM-Curve 5 is very effective to remove organic waste and cleans your tank.
It also comes with an air silencer to ensure quiet operation. The pump wattage of the only 22W makes it very effective at saving energy costs.
SCA-302 includes the silencer, extra-large collection cup, needle wheel impeller, flow control, etc. The construction of this skimmer is not only aesthetic but also durable and long-lasting.