In a marine tank, filters should be able to do 10 times the volume of the tank per hour.
eg: tank holds 100 litres of water so the filter should do 1000 litres per hour.
You need a high flow rate due to the high pH of seawater (pH 8.5). Any ammonia in water with a pH of 8.5 is extremely toxic to fish so you want a big filter to remove the ammonia as quickly as possible.
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Wave makers can be any flow rate and it depends on what you are keeping. If you are keeping seahorses you want calm water and a wave maker is not necessary.
If you have corals, they like water movement so a wave maker is beneficial in providing water movement around the corals.
