Does your biological filter die off over winter? If so how much?

Koi ponds often struggle with high nitrite in spring. But why is this? Does a biological filter die off in winter meaning you start from scratch every year? Or is it just them operating more slowly in the lower temperatures? The answer depends on which bacteria we look at but it’s essential to keep the filter running over winter. This video will help you understand what’s going on

[@MrEnglandbloke]

Great videos!

[@philipbutler6608]

I use septic tank enzymes and bacteria in my pond. I use it all Summer long too. Especially after water changes.

[@thekoilab3944]

That sounds really interesting. What specific product do you use? I might test it but it would be essential to know the exact product to know it’s safe with fish! Thanks

[@Chequr_Prostate]

So I wonder if you should heat your media/containers rather than your pond, although you still have cold water passing through the media so I’m not sure how effective that would be.

[@thekoilab3944]

It’s an interesting idea - you could either isolate it from the pond and heat it which is effectively what I did, or have some sort of heat exchanger to cool the water down as it leaves the filter, and heat the water up as it enters- but that would pretty elaborate!