Biofiltered pond installation in Boise, Idaho

If you can see your fish one week and not the next, biofiltered pond installation in Boise is how I build ponds that stay clear. Murky water, a sour smell, green film on everything and another bottle from the store every month all point to the same missing piece. A biofiltered pond cleans itself the way nature does: with good bacteria living in a filter, breaking down waste before it turns into algae food.

What biofiltration means

Every pond makes waste. Fish give off ammonia. Leaves and uneaten food rot. In a pond without a biological filter, that waste builds up until it feeds algae or harms fish.

A biological filter, or biofilter, is a chamber packed with filter media that has lots of surface area. Helpful bacteria grow on that media. As pond water flows through, the bacteria turn ammonia into nitrite and then into nitrate, which is far less harmful. Plants then take up the nitrate as food. That chain is called the nitrogen cycle, and a biofiltered pond is built to keep it running.

The two filters that do the work

I build with Aquascape components, and a biofiltered pond uses two filters that work as a team:

• The skimmer sits at the edge of the pond. It pulls in surface water, catches leaves and debris in a net and filter mat, and houses the pump. This is mechanical filtration. It grabs the solid stuff.
• The biofalls filter sits at the top of the waterfall. Water is pumped up into it, passes through mats and media where the bacteria live, then spills out over the falls. This is the biological filter.

The rock and gravel on the pond floor give bacteria even more surface to live on, which is a big part of the ecosystem approach. Plants finish the job by soaking up what's left.

Sizing the biofilter

A biofilter only works if it's big enough. I size it by:

• Pond volume. How many gallons need to pass through it.
• Fish load. More fish, and bigger fish like koi, make more waste. A koi pond needs more filter than a goldfish pond of the same size.
• Flow rate. The pump has to push enough water through the filter, matched to the filter's size.
• Sun and debris. A pond in full sun under a big maple needs more help than one in partial shade.

An undersized filter is the most common reason a pond goes green and stays green.

How Boise seasons affect the bacteria

The bacteria in a biofilter are alive, and they care about temperature. In our hot summers they work hard, which is good, because algae grow fast in July heat too. In winter they slow way down as the water gets cold. Every spring there's a gap where algae wake up before the bacteria catch up. I add a bacteria starter at spring startup to close that gap.

Alkaline water plays a part as well. At a higher pH, more of the ammonia in a pond is in its harmful form, so steady biofiltration counts for more here than in softer water. One habit I teach every owner: rinse filter mats in pond water, never tap water. Chlorine in tap water kills the bacteria you spent all season growing.

How I install a biofiltered pond

• I plan the waterfall location first, since the biofalls filter sits at its head
• I dig the pond and shelves, with the skimmer on the opposite side so water moves across the whole pond
• I set the skimmer and biofalls level, run flexible pipe between them, and lay underlayment and liner
• I build up the waterfall with stone around the biofalls so it looks like a natural spring
• I add gravel and rock, plant, fill, condition the water and seed the filter with bacteria

Adding biofiltration to an existing pond

If your pond has a pump sitting in the middle and no real filter, I can usually retrofit a skimmer and biofalls. That's covered on my pond filtration system installation page.

Cost and related work

What changes the price: pond size, how many fish you plan to keep, how tall the waterfall is, how much stone you want and how far the pond sits from power. For a sense of scale, my published starting price for an 8' x 11' Aquascape system pond with a waterfall is $15,500.

A biofilter is one piece of a bigger system. Ecosystem pond installation explains how fish, plants, rock and filters balance each other. If you plan to keep koi, see koi pond installation or my main koi ponds page. Once the pond is running, pond maintenance keeps the filter in shape. Everything else I do with ponds is on my pond contractor page.

Service area

I install biofiltered ponds in Boise, Eagle, Meridian, Garden City, Star, Kuna, Nampa, Caldwell, Middleton, Hidden Springs, Sun Valley and Ketchum.

For biofiltered pond installation in Boise, schedule a consultation. I'll look at your yard, ask about the fish you want and size a filter that can keep up with them.