what is the size of sump

what is the size of sump do I need when I have a 90g tank mainly aiming at reef

 

You can have a 200g sump if you want, it will just give you more water volume. The one thing you need to keep in mind is what ever size you go with just make sure when the power goes out and the tank drains (until it breaks syphon) your sump needs to hold that amount of water.

 

I ran my 90 full reef on a mag 9.5 for yrs after the old Rio 2500 died.. But if you go with a out the sump pump like a little giant or Gen X then about a 1200 GPH will do you and run the skimmer or other stuff also. Just somthing to think about

 

each overflow in the main tank has a maximum amount of flow that it can handle. the water from there enters the sump. the pump should match the tanks overflow rating, also take into consideration the head pressure of the pump. the larger sumps will allow either more room for equipment and water volume. most sumps are made to match the tanks water volume. suggestion: get the sump rated for the next size up. reason: less bubble return. one way to stop the backflow on a power outage is to use one way flow valves.