DIY Aquarium Sump

What Size?

The first thing to determine is what size do you need.  It will depend on what size your main display tank is as well as what equipment will be in it.  Things like if you are going to have a refugium in the aquarium sump, the size of the protein skimmer and what return pump is being used.  Generally I recommend a sump that is approximately half the number of gallons of the display tank.  For example a 75 gallon tank should have a 30-40 gallon aquarium sump.  I prefer to be on the higher side if possible.

What Material?

The next thing is to decide what material should be used.  Acrylic and glass are the most popular.  Personally I prefer glass tanks.  Used glass aquariums are inexpensive to find used and you can get glass cut at most local hardware or glass shops to use for baffles.  For example I found a used 55 gallon tank for $10, bought $30 in glass and $10 in aquarium silicone and had a custom glass aquarium sump.  Acrylic sumps are nice but the materials tend to be more expensive and if you do it yourself cutting the acrylic can take a lot of time. Custom acrylic aquarium sumps can be made but the tend to be expensive.  The choice is up to you but I prefer glass aquarium sumps.

How to layout the aquarium sump baffles?

Laying out the baffles can be a little tricky.  It can be really simple or really complex.  The first thing is to determine how many chambers you need.  You may want one for the protein skimmer, one for the refugium and one for the return pump.  Typically I design the sump so the protein skimmer and refugium chambers water level does not fluctuate.  This can be done by the height of the baffles.  Lets look at this simple 3 chamber aquarium sump.  It will only require three pieces of glass to make.

In this design the water enters the aquarium sump into the skimmer chamber.  The water then flows over the second tallest baffle into the refugium chamber.  It then flows over the third tallest baffle.  On this baffle I sometimes put silicone in some egg crate on the top of it so the macro algae does not float over the top of the baffle.  As for the height of the tallest baffles I typically start at 75% the height of the aquarium sump.  If the height of the sump is 12” the tallest baffle would be around 9” tall.  Once thing to remember is that the sump needs to hold all the water from the display tank that may back siphon in a power outage.  This can be calculated. Click here to see how to calculate water volumes.  The height of the second tallest baffle is typically 1-2” shorter than the tallest one.  This is dependant on the width of the second tallest baffle as well as how much flow is going through the sump.  Typically for higher flow I would use 2”, lower flow you can use 1”.  If you are not sure I would go 2” to be safe.  The skimmer and refugium chambers’ water levels do not fluctuate but the third chamber where the return pump is will.

How to prevent micro bubbles in the return?

The best way I found is to keep to prevent micro bubbles is to keep the return pump as far as you can from the last baffle.  If you look at the above sump design the water has to go around a corner and then the length of the aquarium sump to get to the return.  The water will be pretty calm by the time it gets to the return pump.  I have never had micro bubble issues with this type of design.  Some people use bubble traps.  This can work well but I do not like vertical style.   See picture below of a couple of different types.

This is a vertical baffle design water flows over and under a couple of baffles to help trap bubbles.  If these baffles are not designed correctly micro bubbles can be a problem.

This is a horizontal bubble trap design.  It basically makes the water travel farther before the water gets to the return pump.  It tends to use less glass as the vertical bubble trap and in my opinion is easier to build.