i myself run a saltwater reef tank with no filtration other than a skimmer i have a deep sand bed in the main tank with a bunch of live rock and coral also in the sump below i have a deep sand bed planted with calerpa and in that tank i have 2 sea horses, a couple of snails, a few hermit craps, and a brittle star just to clean up the little bit of fish waste that is produced and may float in and its been workin abosolutely fine on the sump i have lights that are on 24/7 it makes it so the ph does not change becuse ussally at night ur ph will drop when the corals and plants are not photosynthesising i use a Euro Reef skimmer i highly recomend this brand there guite exspensive but work great this tank has been set up for about 2years after the first 6months i started to eleminate the filtration