I removed my bio filter and noticed no difference to water quality, why?

[togapond]

After 15 years, I'm going to rebuild my filter setup. It works well, but I built two things wrong and I end up wet and mucky each week when I clean stuff. My filter rebuild is to address this messy process and remove 'unused' filters.

Part of my filter rebuild involves removing my bio filter 55 gallon barrel, which hasn't had media for 7 years. It sits between my settlement tank and pump for TPR's. One year when my S/G pump failed and it took 2 weeks to get a replacement, my pond got overrun by string algae. My k1 media got tangled in algae and had to be thrown out. I kept monitoring water quality and my nitrite and nitrate didn't change. It's been 7 years and I've not noticed any problems or water quality issues, and I haven't lost any fish.

Can someone explain why I've been okay without it?

I don't overfeed, I do have a birdman S/G filter, settlement tank, lily pond (maybe the nitrogen cycle is going on there?), and waterfall (lots of air forced into there).

[coolwon]

Your fish numbers balance with the biological filter numbers?

[togapond]

Your fish numbers balance with the biological filter numbers?

Is there any formula or way to know how much plant mass will handle X number of koi inches? I'm just surprised that a half dozen lilies can handle my koi.
Or is it pretty well known that some people don't need a bio filter for some ponds?

[*Ci*]

Biobugs grow on all surfaces in the pond, and that accounts for a lot. Also, your S&G is a decent biofilter. Steve (Birdman) used to say that 2x55g S&G’s are perfectly adequate for a reasonably stocked 2000g pond.
So, those things along with your attached lily pond are obviously keeping up with the ammonia production.

[togapond]

Biobugs grow on all surfaces in the pond, and that accounts for a lot. Also, your S&G is a decent biofilter. Steve (Birdman) used to say that 2x55g S&G’s are perfectly adequate for a reasonably stocked 2000g pond.
So, those things along with your attached lily pond are obviously keeping up with the ammonia production.

So if my plan is to remove my S&G filter and replace it with a bead filter (which I could put in my filter pit below water level, unlike a S&G), I'm guessing that could be bad, or at least risky in the short term?

Has anyone determined if S&G is better for fines(clarity) and bio filtering, vs a bead filter?

[coolwon]

Your fish numbers balance with the biological filter numbers?

Do your numbers not speak for themselves?

You are very fortunate.

Normally it's great tales of woe.

Get the muck from the fallen plant life out, before it rots.

Any how!

[SimonW]

My biofilters had been used for over-wintering my koi during the winter 2020-2021, and they were all established and well-functioning before I moved my koi into the out-door pond last summer together with them.

To my big surprise the filters were almost "dead" when I took them indoors again last fall to equip the over-wintering tanks. I got no ammonia spike, but nitrite spikes.

So I guess that the algae on the walls of the out-door pond was so effective at removing ammonia that the nitrite-oxidizing bacteria could not get enough food. Ammonia oxidizing bacteria are faster at recovering.

[Enrgizerbunny]

My biofilters had been used for over-wintering my koi during the winter 2020-2021, and they were all established and well-functioning before I moved my koi into the out-door pond last summer together with them.

To my big surprise the filters were almost "dead" when I took them indoors again last fall to equip the over-wintering tanks. I got no ammonia spike, but nitrite spikes.

So I guess that the algae on the walls of the out-door pond was so effective at removing ammonia that the nitrite-oxidizing bacteria could not get enough food. Ammonia oxidizing bacteria are faster at recovering.

What is the difference in volume between your indoor tanks/ outdoor pond? Lower concentrations of food would support lower populations of bacteria, even if the overall volume of food was the same.

[Enrgizerbunny]

The sand/gravel filter has lots of surface area. That's probably where your biofilter is located now.