Reason. Is a sump the same as a wet @ dry system as I had.?

Your sump is the same container your bio balls would have sat above and into on your old wet dry system. Back then it was often just an aquarium with bio ball chamber added on. The sump would be the actual thing holding the water under your aquarium, whether it has bio balls for a wet/dry setup, or whether it is just down there to hold water and keep your pump, heater, and protein skimmer from cluttering up your display tank. These days an entire wet dry system is often referred to as a "sump" which isn't entirely correct, but it is usually regarded as close enough.

The principles are the same now as they were 15 years ago, it's just that the technology has improved. Acrylic is used most of the time now to build them, and there are more of them available already made and "plug and play" vs. having to put together every piece yourself as we used to have to do back in the day. Welcome back to the hobby.

A sump can be set up as a wet/dry filter, or as a conventional filter.

The idea with a wet/dry is that the water is trickled over the media, so it's exposed to both air and water at the same time, which makes it an even better environment for the bacteria. They stay wet, AND get lots of oxygen from the air.

So you rig up the sump with a plate across the top, and the water flows onto this. There are lots of small holes in the plate, and this lets the water rain down on the media in the filter. You then pump the water out of the bottom of the container.

Ian

To put it simply, the sump is the reservoir of water that goes under the tank. You can set up a sump in a million different ways, including the wet/dry approach. My favorite is a refugium style sump as the wet/dry causes nitrate issues in saltwater where a refugium or other natural filtration approach reduces nitrates.

So, to answer the main question, a wet dry is a sump, but not all sumps are wet/dry (and a wet/dry can usually be converted to a natural filtration approach with little effort).