What Sized Tank For Sump?

Hello fellow fishlorians!
I have a pump with a flow rate of 1100 GHP. I am going to use a sump along with a canister filter on my 125 Goldie build. What size tank should I use for the sump? I can make my own sump so I don’t need to buy one.

 

Wow that's a big pump for a sump. That is capable of turning over a 100 gallon sump 11x.

 

Oh. I don’t think that I can fit a 100 gallon tank under the stand.

 

You can really make it any size you want. I have a 30 gallon sump (holds 23 gallons) on my 90 gallon aquarium. It really just depends on how much extra water volume you want. For 125 gallon I wouldn't go smaller than 30 gallons, but really you can put as large as your under cabinet area will hold. On a side note if you aren't familiar with sumps. Fill it to a desired level and kill your return pump, and check to make sure it doesn't back flow over. If it's stops mark a full fill line. Makes it easy to know how much water to keep in the sump. Also, if you set it up correctly you don't need the canister filter.

 

I see a lot of numbers get thrown around. Bacteria filtration like a slower flow so water spends more time in contact with it around 5x turn over of sump. Mechanical filtration can be done at any flow 10x turn over. With goldfish having such a bio load I would say 1/4 sump to tank ratio so around 40 gallons. So to give a happy medium between biological filteration and mechanical filtration lets say 8x turn over. Pump would be rated at 320 gph at 4 feet. Just an example.

 

It's not how much you turn over the sump it's how much you turn over the tank. Also, you will want to note the head pressure on the return pump. Angles and rise will take the 1100 gallons per hour down. If I remember correctly it is 1 pound of head pressure for each 4 feet of rise, and 1 pound for each angle. The pump box should give you the GPH per head pressure.

 

The sump size should be at least 30 to 40 percent or bigger. I assume your tank is 6ft by 18 inch wide. So depending if you make the stand and how tall it is, dictates what size tank you can use. if you can fit a 75 gallon tank under the stand you can have huge amounts of mechanical biological plus room for a refugium. If not a 55 gallon or a 40 gallon long both being 4ft long.