Answer: LAKOS separators and sand filters are both designed to remove solids from liquids, but have advantages over each other depending on the application.
A separator is designed to remove solids with a specific gravity at least 1.5 times that of the carrying liquid. Separators require very little, if any, maintenance because they have no moving parts. The pressure loss across a separator is predictable and steady and only varies with flow rate. Separators require minimum liquid loss for the purging of collected solids, and can also be equipped with an optional solids recovery vessel that can eliminate liquid loss. However, separators do not generally help with liquid clarity (turbidity) and are ineffective on organic material, such as algae.
A sand media filter is designed to remove finer solids (down to 5 microns in size) with low specific gravities. Sand filters are used when finer filtration and liquid clarity (turbidity reduction) are a requirement. Sand filters do require more operational maintenance (more moving parts) and use more liquid for backwashing of the sand bed to remove the collected solids. Pressure loss across a media filter varies, as solids are collected and enter a backwash cycle when they reach a predetermined pressure loss. However, sand media filters are very efficient at removing a wide variety of light, organic solids.