Earthworms in filter media

AndyPondJuly 21, 2014

Liner pond was built in February. Plants and fish added in early spring. Rinsed out my waterfall box biofilter for the first time this morning and found lots of earthworms in the mesh media! They were several inches long. There was also quite a bit of muck/sludge. I assume the worms don't hurt anything and may even be beneficial. I also assume that they crawled in through the top of the filter. The filter is 2 layers of mesh mat; some bags of activated carbon on top of that; and some mesh bags filled with scrubbies on top of that. I wonder how often such a set-up should be rinsed (with pond water of course).

This post was edited by AndyPond on Tue, Jul 22, 14 at 0:43

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We have a worm farm to raise earth worms to feed our koi.(100 percent
Our fish love them. How big are your fish? Ours are big so they can
manage a big worm. You'll have to cut your worms up if your fish are
small. We also water all our plants and flowers with the muck/sludge
from the filters.

    Bookmark   July 21, 2014 at 7:56PM
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waterbug_guy(Phoenix AZ (Melrose))

I'm not sure if you're asking a question but earthworms getting into filters and ponds isn't unusual, not super common, but not unheard of. I've only seen in filters mounded in the ground so the worms can travel along the ground and fall into the filter under the lid.

If you're asking for suggestions on how often to clean the're not going to like this but here goes...

Activated carbon does indeed remove small bits of stuff. Used in drinking water filters. Just like drinking water filters the activated carbon only lasts so long because it becomes clogged with trapped particles. In drinking water systems the activated carbon is placed as the very last stage, after reverse osmosis. That's because they want the activated carbon to only get super clean water so it doesn't clog as fast.

In a pond environment activated carbon would clog in seconds, maybe minutes. You won't notice any change because stuff that clogs activated carbon is too small to see, sub-micron, smaller than bacteria.

So I wouldn't worry about cleaning the activated carbon. I'd throw it out.

The mesh and scrubbies are called static submerged least I assume they're below water. These are OK as a pre-filter to protect a pump, catch leaves and large stuff. In that case you just clean them when clogged. It's fine to rinse with chlorinated water if you like.

However, if these media is intended as bio filter media there is a problem. Any bio media that ever has to be cleaned is not actually bio media at least for growing bacteria that consume ammonia and nitrite. These bacteria need media that stay clean otherwise they can get to the ammonia, O2, carbon and stuff they need. Here's a picture of what the bacteria look like:

The black dots are the bacteria and the gray structures are the bio film (jelly like stuff) the bacteria produce to anchor themselves and get up into moving water. In static submerged media that has to be cleaned means dirt can collect on the media. The fins are very small as you can imagine. It takes almost no dirt to clog those structures. There will be some areas that stay clear, so this media can grow some of these kinds of bacteria, but not much. A lot more will being growing on the inside of the pump pipe/hose because the flow is so intense it helps keep the bio film clean.

So there's no good answer for how often this kind of media has to be clean to function as a good bio filter. If you wanted it to perform more like a Trickle Tower, Moving Bed or Bakki Shower you'd have to clean the media every hour maybe. Those filters are self cleaning which is why they perform so much better. But no one of course is going to clean media every hour, that's crazy.

Beyond that you're into a Catch-22. As dirt clogs the bio film the ammonia converters die or never set up house in the media. So really the media is so poor it doesn't really matter how often it's cleaned.

Not trying to bum you out.

    Bookmark   July 21, 2014 at 8:26PM
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Thanks for the info waterbug_guy. The mesh mats do most of the filtering and the scrubbies on top probably do more bio. I suspect the activated carbon does nothing but I left it in there anyway (figured I'd take it out sometime this summer). There was quite a bit of muck in the mesh mats and that's where most of the earthworms were I think. Clearly there is plenty of O2 in the box since the worms were thriving. I think I better rinse the mats every 2-3 months.

    Bookmark   July 22, 2014 at 12:53AM
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waterbug_guy(Phoenix AZ (Melrose))

There is indeed no harm leaving the activated carbon in there.

And no harm cleaning the mats whenever you like.

    Bookmark   July 22, 2014 at 9:46AM
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I get brown leeches in my filter media. They kind of look like worms too. I guess they are harmless.

    Bookmark   July 28, 2014 at 5:38PM
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