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8.6.7. Foam Sump

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Author : David Bogert

Published :

Time To Read :
2 minutes
Difficulty : Level 7

Excerpt :

Foam in a sump makes for a very effective low maintenance aquarium filter.
There is one type of foam sump that is VERY attractive to those who are cowed by the complexity of a fluidized bed sump. It is a foam/wavemaker sump.

This is what it looks like:

Foam Sump
Foam Sump

This will have about 60% of the biofiltration capacity of the same volume K1 fluidized bed sump. It will be much easier to set up than the K1. It is much quieter than any of the fluidized K1 designs. If the sump is made very large compared to the bioload and a high protein food is fed, this sump design will never need maintenance.

The surface area of the coned red top piece of foam is very large and the wavemaker insures a large flow of well oxygenated water over this large surface. These two factors insure the top red piece of foam will never foul.

Labidochromis caerulus
Labidochromis caerulus

The Design

Let us go through a build for a 110-gallon heavily stocked mbuna aquarium. What is needed?

Bill of materials:

  • 40-gallon breeder aquarium 17 inches high, 36 inches long, 18.25 inches wide.
  • 3 inch thick 20 ppi foam red waffle 26×19.5 inch Poret foam sheet
  • Two 4 inch thick 30 ppi blue 26×19.5 Poret foam sheets
  • Thirty-gallon under-gravel filter
  • One bladed circulation pump
  • Two acrylic sheets 18.25 by 13 inches in size, siliconed into the tank, 25.5 inches apart. No holes are needed in the acrylic
  • High Pressure Pump capable of lifting 5 feet of head.

This will give about 10x18x26=4,680 cubic inches 4,680 = 2.7 cubic feet of foam. At roughly 340 square feet per cubic foot of foam, this gives 918 square feet of media surface area. At 100 square feet per pound of fish, this is 9.2 pounds of fish. This is very roughly 7 adult Oscars, or 80 or so adult mbuna, which is HUGE. What might be more amazing is that a K1 fluidized bed in the same volume gives 12 adult Oscars and 140 adult mbuna.

The bladed circulation pump at the surface in the 4 inches or so of free water space will aerate the water well, which is important. The bladed pump will also keep the feces and large particulate matter agitated and broken up rapidly.

Mesoheros Festae
Mesoheros Festae

For more information on sumps click on the following links:

8.6.1. Sumps in Depth

8.6.2. Static Submerged Media Sumps

8.6.3. Trickle Filters

8.6.4. Wet-dry Sumps

8.6.5 Fluidized Bed Sumps

Note that many beginners are concerned about how to flow the water to a sump. The common refrain is “my aquarium isn’t drilled, how does the water get to the sump?” Click on this link to get some ideas:

14.7. Overflow Devices