I need some help unpacking the wide world of pond filtration

[Collin]

Hi everyone,

I'm currently in the process of constructing a new pond in my backyard and I need some guidance for choosing a pond filter. I've seen people do "bog filters" as well as build what can best be described as giant sumps. Here's the thing: I don't have that kind of space and I don't want a giant filter setup to take away from the look of the pond.

The pond is going to be 2 feet above ground and the footprint is going to be 6'x8'. I have a much smaller pond which this new one will be replacing so that my 4 koi and 1 comet can have MUCH more space. In the current pond, we're using a box filter which is... fine I guess? It keeps the water clear and has space for bacteria, but holy cow does it need to be cleaned extremely often.

I've seen internal filters, pressurized filters, and so many other things. There doesn't seem to be the kind of community around ponds as there is for indoor aquariums, so finding consistent advice has been a challenge.

I saw in one of Cory's videos that he had what looked like an external pressurized filter for his pond inside of a hidden compartment of sorts which looked really cool.

What sort of questions should I be asking myself in order to figure out what kind of filter I should get? I'm honestly really lost.

[Cory]

In general I feel like pond filters are very overpriced. A DIY solution is a good option. Any filter you have will need lots of cleaning because lots of stuff falls into a pond. Lots of water changes help. Usually pond filtration is disproportionally sized to not have to clean it all the time. So you might need filtration that takes up the size of 1/3-1/2 the pond underground/away from the pond, back flushing and water changes to keep what we think of as clean in an aquarium. Or if you got more natural, all you really need is some air in the pond, and water changes. Anything you add to that will help make it a bit visually cleaner, but unlikely to be needed to keep it chemically safe for the fish.

[Patrick_G]

I use a home made box filter. The water stays clear and the Nitrates are low. 
 

Yours will be 719 gallons so a good off the shelf solution might be an Oase UVC 1000. It’s rated up to 1000g and had UV built in. Runs about $150. Maybe you could use you current pond as a planted bog filter inline with the Oase. 
 

 

 

Edited March 22, 2021 by Patrick_G

[Collin]

10 minutes ago, Cory said:

In general I feel like pond filters are very overpriced. A DIY solution is a good option. Any filter you have will need lots of cleaning because lots of stuff falls into a pond. Lots of water changes help. Usually pond filtration is disproportionally sized to not have to clean it all the time. So you might need filtration that takes up the size of 1/3-1/2 the pond underground/away from the pond, back flushing and water changes to keep what we think of as clean in an aquarium. Or if you got more natural, all you really need is some air in the pond, and water changes. Anything you add to that will help make it a bit visually cleaner, but unlikely to be needed to keep it chemically safe for the fish.

Can you recommend any resources for building a DIY system?

[Cory]

https://www.koiphen.com/forums/showthread.php?68132-Birdman-s-Sand-Gravel-Filter