Things You'll Need
- Coarse sponge
- PVC pipe
- Drill
- Acrylic baffles
Instructions
Check the flow rate through the sump. For a reef aquarium, you only need up to four times the total display aquarium volume flowing through the sump per hour. This means if you have a 50-gallon aquarium, your flow should be 200 gallons per hour (gph). Too much flow can cause the water to become chaotic and splash. This mixes air into the water and can cause bubbles in the aquarium.
Stop any air intake to the return pump. If the water level in the chamber of the return pump is low enough, a whirlpool will form above the inlet for the return pump. This sucks in air that the pump will grind up into tiny bubbles. To stop whirlpools from forming you can increase the water level in the part of the sump holding the return pump. Use a smaller return pump or insert a piece of PVC pipe drilled with many 1/4-inch holes into the intake of the pump.
Build a bubble trap into the return pump's chamber in the sump. This system looks like a "U" where the water flows over one side, under a second baffle, and then up over a third baffle. This system allows the bubbles to rise to the surface before they enter the return pump's chamber.
Add a sponge to the bubble trap. If you have added the bubble trap and there are still bubbles entering the return pump, you can add a coarse sponge between the baffles to absorb the bubbles.
Add a filter to the outlet of the protein skimmer. Freshwater aquariums do not use protein skimmers, but if you have one, it may be a source for the bubbles. Protein skimmers aggressively mix air and water to remove dissolved organic compounds, and sometimes the bubbles can enter the sump and flow into the aquarium. To inhibit this, add a filter to the outlet of the protein skimmer. You can use a coarse sponge or granular activated carbon.