Adding a 21 to my 65, need advice.
- Thread starter Authentic
- Start date
there is a calculator on home page do it for both display tank and your other tank and add them together then check how much room you have in your sump.... if number of room needed is less than room available ...walla ... id like to see your addition as im about to takle adding a frag tank to my system so post some pics 
Susan Lohrer
New member
I didn't use a calculator, just did the math.
My 65-gallon DT is 24 inches tall, so it holds about 2.7 gallons per inch. My 10-gallon sump holds (I can't remember the height, so let's take a guess) 1.2 gallons per inch. To ensure extra wiggle room, I counted only the sump volume above the baffle height. For example, 3 inches would hold 3.6 gallons of water from the DT, the plumbing, and the skimmer (plus whatever else you have that would drain into the sump). Knowing the volume of water your sump can accept lets you position your overflow and return jets high enough in the DT that you can't overflow your sump. In my tank's case, the math tells me to keep my overflow and return jets within 1.3 inches (the measurement that holds 3.6 gallons in the DT) of the DT's water surface. And there's still a little wiggle room from not counting the extra space in the pump section of the sump.
My 65-gallon DT is 24 inches tall, so it holds about 2.7 gallons per inch. My 10-gallon sump holds (I can't remember the height, so let's take a guess) 1.2 gallons per inch. To ensure extra wiggle room, I counted only the sump volume above the baffle height. For example, 3 inches would hold 3.6 gallons of water from the DT, the plumbing, and the skimmer (plus whatever else you have that would drain into the sump). Knowing the volume of water your sump can accept lets you position your overflow and return jets high enough in the DT that you can't overflow your sump. In my tank's case, the math tells me to keep my overflow and return jets within 1.3 inches (the measurement that holds 3.6 gallons in the DT) of the DT's water surface. And there's still a little wiggle room from not counting the extra space in the pump section of the sump.
