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Creating a biological filter

Posted by julie11 (My Page) on
Fri, Apr 20, 12 at 10:19

I am slowly trying to do my pond "right". We dug a pond 4 years ago. It holds around 2000 gallons. I know I don't have enough biological filtration. I have a pump that I think we calculated right for size, but it is basically being diverted around the pond and back in, without much in the way of filtering. The filter box catches the big stuff, obviously, but the nasty stuff/gunk is diverted into a "waterfall box" that I created myself, out of a piece of pond liner and bricks. It's basically a big depository on the side of the pond, which I built a waterfall around.

However, since it's not a self contained area, the water pushes through some bio balls and right back into the pond. I can fill that area with filter material like sponges/bioballs, but it has no "top". Any suggestions for what I can add to the top of this area to catch more gunk and nasty stuff? The bioballs do work to a degree, but any time I turn off the pump, this area empties, and so when I turn it back on, a lot of the gunk gets swept back into the pond by the force of the water. I need a better entry point back into the pond.

I'm including a link to a picture to help with this. I also suspect this area should maybe be bigger, or I could add a second pump and waterfall area to the other side?

Follow-Up Postings:

RE: Creating a biological filter

Also, I know I have the wrong kind of rock in that waterfall, that is only encouraging the green water. I have to buy the proper kind of river rock this year, and will take out all this rock to create more paths in the yard.

In the future I'll buy a set of biofalls, but when I created this, I didn't know what I was doing. I still don't, but I'm trying to learn! I've read up on Skippy Filters, but this isn't quite like that because again, it has no "top" for the water to be filtered through a smaller area.

RE: Creating a biological filter

I built a biological skippy Filter and posted pictures. See the link below. I looked at your picture and I think you might be able to adapt this idea to your filter box. The main thing, I think, is layers of filtering material with some kind of a grid to hold it all down on top. I put water hyacinth and other plants on it and you can't even see the water in the filter by mid summer.

I love this filter except for the pipe outflow to the stream. It can clog up easily with just a leaf or other bit of debris. I am going change to a lip type of outflow this spring.

Once it gets going, the water clears right up in the spring and stays clear all summer. I never clean it and in the fall just drain it and leave the filter material in it all winter, start it up in the spring and off we go. I do use Microb lift to get it seeded with the good bacteria but other than that, no other effort on my part.


Here is a link that might be useful: Skippy Filter

RE: Creating a biological filter

Thanks, Anne! That is very helpful, and that is a great set of photos!

Two questions about materials: what is the grate material? And AC filters... can I find those easily at a Lowe's/Home Depot? I was there today asking for more of the filter material I have for my pump box, but it's very tiny. Everyone there was stumped. This looks exactly like what I need!

RE: Creating a biological filter

The grate material is what they use as the grids you see in florescent lights.

I'm not sure what the filter material is called other than that it is washable. It comes in flat sheets that are wrapped in plastic.

The scrubbies I made myself from nylon netting I got at the fabric store. See the link below for the thread about them.


Here is a link that might be useful: How to make scrubbies for filter

RE: Creating a biological filter

Hi, Julie. Just replaced the a/c filter in my skippy & actually dug the packaging out of the trash to answer your question. Yes, you can easily find them at the big box stores as well as Wally World (provided your store occasionally stocks its shelves - mine doesn't).

I usually buy them at Lowe's. Don't recall the brand name but they are bright blue which makes them easy to spot. This year, hubs picked one up at WW (it's green). Here's the brand/label info:

NaturalAire 20 X 30 cut-to-fit
Washable, Reusable & Biodegradable

I clean my skippy 2X a yr in spring & fall. I clean the ac filter in the fall & replace it each spring as it's showing signs of decomp then. This past fall I skipped the cleaning as we seem to have skipped fall here and transitioned from summer directly to winter and I don't 'do' cold weather lol. Point being, I discovered after a year, the filter had virturally disintegrated. Note it is BIODEGRADABLE.

WARNING: This is great in a skippy but DO NOT use this to surround a submerged pump.

RE: Creating a biological filter

Thanks so much! This is really helpful.

I managed to break the glass sleeve inside my UV light while installing a new bulb, but was happy to find that replacement part fairly cheaply.

Meanwhile, terror reins in my pond: found a dead finch floating, and I assume this was a failed bullfrog killing. We saw the dustup, but I didn't notice the bird go under. I assumed the frog was after a bumble bee that went down at the same time (and escaped, very indignantly).

We cleared all of the tadpoles out of our pond on our spring cleaning, but have 5-6 adults terrorizing our yard wildlife. They're gorgeous and fun to watch, but man, they're ruthless.

RE: Creating a biological filter

I'd be relocating those bad boys pronto. We've always had tons of toads here but I've always prayed for a frog. finally took up residence after all these years. Hubs has seen it several times but I've only caught a quick glimpse, just once before he disappeared into the pond. He's big enough that I'm keepin a sharp eye out for him. At the first sign of foul play, he's outta here.

Moral of this story: be careful what you pray for, lol.

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