Healthy Fishpond With No Filter?

[Mehitabel]

Hi All.
I'm fairly new to pond-keeping. One thing I've believed right from the start is that if you're going to keep fish in your pond, you MUST have a filter of some kind. I have a 750L pond with about 15 small goldfish and a good stock of vegetation. But whenever the filter packs up, I panic, believing it'll only be a matter of days before the fish start to suffer.
But............ I have a friend with a very well-established pond, about twice the size of mine, with a lot of large goldfish. It's crammed with vegetation - don't know how the fish can move. But what really baffles me is that he doesn't have a filter, just two solar oxygenators. This being the UK, they don't do a lot of work. The pond is never cleaned or cleared, nor is the water changed.
So: Have I been misled? Am I worrying unnecessarily when my filter system throws a fit? Can you really have a healthy fishpond without one?
[Pics are of my friend's pond]

 

[Mmathis]

There are 3 types of filtration: mechanical, biological, and chemical. All are important, but it depends on what you have in your pond. If you have plants, a low fish load, and some type of water movement (through a pump, bubbles, or waterfall), it’s possible to get by without a filter. The secret is keeping all of this in balance. If your fish are healthy, the rest is all up to you. A common misconception is that clear water equals healthy water. It doesn’t. Your water can be crystal clear…..and still not be healthy. You can have algae and maybe not be able to see the bottom of your pond…..but still have good water quality. You want healthy, balanced water, that doesn’t go through drastic changes.

This is a simplified representation, but in no way implying that THIS is what you need — just an example of what each type of filtration means. There are many types of mechanical filtration. Your biological filtration is all about the biofilm of beneficial bacteria that collects on pond surfaces — it doesn’t have to be incorporated into a filter. To me, chemical is more about correcting what the mechanical and biological can’t keep up with (for example pH, KH, GH).

A good liquid test kit (not strips, which are less reliable) is always your friend if you have questions about water quality.

 

[JRS]

Simply a replication of the ecosystem in a natural pond. The plants are the filter. Nitrifying bacteria, found in great concentration in our artificial filters, grow naturally on all the pond surfaces.

We as pond and aquarium keepers tend to unbalance things by putting too many fish, too much food, saving all the babies, killing all the ugly algae, and things like that which requires supplemental filtration to keep everything alive in good health.

 

[Lisak1]

What @JRS said. Left alone, nature will indeed establish the perfect ecosystem.

 

[Mehitabel]

Simply a replication of the ecosystem in a natural pond. The plants are the filter. Nitrifying bacteria, found in great concentration in our artificial filters, grow naturally on all the pond surfaces.

We as pond and aquarium keepers tend to unbalance things by putting too many fish, too much food, saving all the babies, killing all the ugly algae, and things like that which requires supplemental filtration to keep everything alive in good health.

That was my first reaction . But my friend's unfiltered pond has far more, and far bigger, fish than mine.

It doesn't help that local fish suppliers always ask, when you buy fish, if you have a filter. Next time, I might just say "Yes: Nature."

Lots of food for thought here. I might even - carefully - let my pond "go rogue" the next time my filter dies..

 

[Mmathis]

@Mehitabel All ponds are different. What is the water volume to fish (size) ratio of your friend’s pond?

 

[Mehitabel]

@Mehitabel All ponds are different. What is the water volume to fish (size) ratio of your friend’s pond?

I'm not sure, but there are a LOT of large fish.

 

[chibae]

I'm new here but, this is my experience. I have a 30 gallon, half barrel pond in USA zone 7A. I have had it since 2020. It has stayed fairly self sustaining, until this year. (long story, needs a separate post) It has stayed with fairly clear water, but not crystal clear. It has about 8 " worth of fish, annual floating plants, local visiting frogs,and snails that came on the plants. I use a solar powered fountain for aeration, and weekly clean the sides and do a partial water change. Each week I also remove the fountain and clean out it's filter sponge. For three years I had no problems with fish and snails overwintering. i am currently planning on a second, larger pond that will be mechanically filtered.

 

[GBBUDD]

You have graduated from new pond syndrome. And now your looking at a build up of waste be it from the fish plants or blowing dust.
This stuff builds up over time and sooner or latter it will tip the scale to more algae then we would like. But in the same breath if you clean to touroghly the pond will have to start over.
Biggest steps we can take is not over stocking or feeding and keep with a good maintenance schedule.