Yes and no. Depends.
A fish-only may benefit from a filter in the system, but!
Here's a list of useful facts to consider.
1. ONLY live rock and sand can break somewhat-harmful nitrate all the way down to harmless nitrogen gas. Bioballs can't and a filter can't. They take waste down as far as nitrate and stall there. Nitrate builds up and up until there's a cleaning-out of same.
2. Fish can tolerate higher nitrate than corals can. They'd probably rather not tolerate it, but they do. Still try to keep it as low as possible.
3. With corals, try to keep the nitrate under 5. The touchier the coral, the more so.
4. your sand and rock bacteria can dispose of nitrate and convert it to harmless bubbles of nitrogen gas that float up and away. But---cleaning a filter takes away some of their 'food' and creates situations of boom-and-bust as far as their population levels so. If you DON'T clean it, the nitrate buildup in the filter can swamp the capabilities of the system. In a coral reef this is not a good thing at all. In a fish-only it can get so extreme it becomes bad for fish.
5. big carnivores create a lot of waste, and some are very messy eaters.
6. veggie-vores kind of cycle round and round: eating algae that regrows fertilized by poo.
7. A filter, even a filter sock, can prevent copepods and mysis from your sump from making repeat round trips. These small creatures ordinarily escape your sump, survive the trip through the pump's impeller, live in the DT a while, then get swept down again and back to the sump. You will lose some of this wealth with a filter sock.
8. some corals (acroporas, notably) like water crystal clear: with them a filter sock is a big help.
9. some corals (lps, softies, etc) can eat the detritus, so a filter sock may take away some of their food supply.
10. your skimmer is an important filter, and it removes something ordinary filters won't: amino acids. Again, lps corals and softies can sop that up, but may not get enough of it out to keep the tank healthy---depending on what fish you have and how messy they are. Big predators and fussy corals like acroporas are most dependent on a really strong skimmer. A so-so skimmer is ok with less fussy corals and less messy fish.
In other words---it's all relative. Read, think about your own situation or proposed tank, and understand where you fit on the continuum.
A fish-only may benefit from a filter in the system, but!
Here's a list of useful facts to consider.
1. ONLY live rock and sand can break somewhat-harmful nitrate all the way down to harmless nitrogen gas. Bioballs can't and a filter can't. They take waste down as far as nitrate and stall there. Nitrate builds up and up until there's a cleaning-out of same.
2. Fish can tolerate higher nitrate than corals can. They'd probably rather not tolerate it, but they do. Still try to keep it as low as possible.
3. With corals, try to keep the nitrate under 5. The touchier the coral, the more so.
4. your sand and rock bacteria can dispose of nitrate and convert it to harmless bubbles of nitrogen gas that float up and away. But---cleaning a filter takes away some of their 'food' and creates situations of boom-and-bust as far as their population levels so. If you DON'T clean it, the nitrate buildup in the filter can swamp the capabilities of the system. In a coral reef this is not a good thing at all. In a fish-only it can get so extreme it becomes bad for fish.
5. big carnivores create a lot of waste, and some are very messy eaters.
6. veggie-vores kind of cycle round and round: eating algae that regrows fertilized by poo.
7. A filter, even a filter sock, can prevent copepods and mysis from your sump from making repeat round trips. These small creatures ordinarily escape your sump, survive the trip through the pump's impeller, live in the DT a while, then get swept down again and back to the sump. You will lose some of this wealth with a filter sock.
8. some corals (acroporas, notably) like water crystal clear: with them a filter sock is a big help.
9. some corals (lps, softies, etc) can eat the detritus, so a filter sock may take away some of their food supply.
10. your skimmer is an important filter, and it removes something ordinary filters won't: amino acids. Again, lps corals and softies can sop that up, but may not get enough of it out to keep the tank healthy---depending on what fish you have and how messy they are. Big predators and fussy corals like acroporas are most dependent on a really strong skimmer. A so-so skimmer is ok with less fussy corals and less messy fish.
In other words---it's all relative. Read, think about your own situation or proposed tank, and understand where you fit on the continuum.
