Under Gravel Filters

Why Undergravel Filtration Systems Fail

Undergravel Filtration Systems use gravel at the bottom of the pond for both mechanical and biological filtration. Mechanical filters trap solids. Other mechanical filters such as skimmers and sieves make removing the trapped debris easy. With gravel at the bottom of the pond serving as the mechanical filter … how do you remove the debris trapped in the gravel? Biological filters use media that provide surface area to grow beneficial bacteria. The bacteria remove ammonia and other dissolved organics from the pond. Other biological filters such as Hydro Vortex™ waterfalls filters and HydroBead™ Vortex bead filters are backflushable. Periodic backflushing of the biological filter keeps the media free of solid organic matter so the bacteria can do their job more efficiently. With gravel at the bottom of the pond serving as the biological filter … how do you backwash the gravel? Over time, gravel at the bottom of the pond will clog with leaves and other debris that is blown into the pond, as well as 100% of the fish waste. Clogged filters force water to “channel” around the media instead of through it. Channeling water is then not filtered. Bacteria need food and oxygen to survive – with water channeling around the media – the bacteria die off. Dead bacteria and decaying organics in the biological filter become a haven for parasites and other diseases that can kill your fish!
Separate Mechanical and Biological Filtration System
Undergravel Filtration System
Simple, inexpensive cleaning and backflushing of each component as they are external of the pond
Difficult, very expensive to clean as the gravel is inside and at the bottom of the pond
Cleaner ponds, less algae, healthier fish
Dirtier ponds, more algae, less healthy fish