Never had any problems with salt creep, even after adding an mp40

I think salt creep just likes me. I don't have a ton of splashing but it seems I have salt everywhere.

I use 2 glass baffles. The first is 9-10" tall, siliconed to the sump bottom so that it creates a "skimmer box" that has very stable water level, which improves skimmer efficiency. If you have no baffles, your water level might fluctuate a bit, even with an ATO, but with a skimmer box, no fluctuations.

The second is at the far end of the sump, with room an inch wider than the biggest pump I'm going to use as a return and its about a cm or so above the bottom of the sump. The center chamber is filled with rubble, extra live rock, macro algae, etc. This allows water to pass through without any bubbles on your return.

I make the skimmer box big enough to hold the biggest skimmer I'm likely to use, plus enough room to add some extra equipment, like media reactors & heaters & filter sock.

Unlike a lot of others, I have a big skimmer (90g wide - 48" x 24" x 18" tall) so I have room for everything. If space is an issue, the center chamber can be made smaller cause the rubble and chaeto will trap the bubbles anyways.

Anthony