Turtle Tank Bog Filter

My process of taking found parts and creating a bog filter (aka veggie filter) for my turtle tank. Bog filters are used primarily for ponds, but is working quite well for this indoor tank.

My…eh hem…highly technical drawing of the filter…I modeled this with anoxic filtration in mind. Here’s a good overview of the anoxic process if you’re interested:

The turtle tank. Since the canister filter I had broke, I’ve been doing 100% water changes every week. That’s 40 gallons of water every single week.
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My haphazard gathering of materials. I don’t really have a workroom, so I worked in my living room. That’s a 3 gallon beverage dispenser, a small submersible pump (90 gph, I believe), a pipe extender, a slotted plastic basket, screen door replacement screening, waterproof tape, aquarium sponges, 2 sizes of biological filter medium (really just different shapes of baked clay) and gravel used for planted aquariums.
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Action shot! Kidding. Just a bad photo. Here’s the beverage dispenser. I figured since the process would be to push water from the tank up through the filter, the dispenser was perfect. It already had a preformed hole in the bottom and was water tight.

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The top, however, had no such hole, so it was drilling time! I planned to use a hole saw to cut the 1 1/2″ hole I’d need to feed the pipe extender kit through, so I needed to drill a 3/4″ hole for the center of the hole saw to sit in. If you’ve ever drilled a hole in acrylic, you know that it takes a low, slow drill to keep from cracking.
First hole, 1/4″ bit.
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Second hole, 1/2″ bit.
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Third hole, 3/4″ bit.
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My beloved hole saw bit! You can see the center drill bit that I needed to pre-drill for.
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Success! The hole is complete. Right about now I looked like I’d been snowed on with acrylic dust. Use a mask, kids. I didn’t. Because I’m impulsive and not safety conscious.
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I’m not entirely sure how exactly the pipe extender is supposed to work for plumbing, but after combing the plumbing sections of three hardware stores, I thought it would work well for this. It had both a female and male adapter side, and best of all, the pipe itself accordioned (that may not be an actual word, but you get the point…) into the shape I needed. Since this outflow needed to make a 90 degree angle into my tank, the flexibility was key. A little RTV silicone and a 24 hour curing period make the whole shebang water-tight.
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I’m both cheap and opportunistic, so when I saw this plastic spout that came with the dispenser, I felt I needed to at least try to reuse it…
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Fortunately, the interior diameter of the remaining spout was a clean 1/2″, and I knew I could make that work with the tubing I’d need for the pump.
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Check. That. OUT. Perfect fit. I also sealed it up with that same RTV silicone and added a wrap of waterproof plumber’s tape for good measure.
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Here’s the slotted basket I used to house most of the media and the plants. I cut out a slot in the top to accommodate the outflow pipe, and lined it with left over window screening I had from a time when I *may* have put a 2×4 through a screen door in my last apartment..
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The outflow pipe in place!
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Here’s a photo from the side that shows the pump (bottom right corner in the tank) that I covered with a filter sponge to act as mechanical filtration and keep large solids out of the main filter, and how it attaches with tubing to the spout I cut apart.
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Close up of the joint. Totally water-tight!
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As a plant hoarder, I had no need to buy any plants for this project. I used cuttings of several plants I know don’t mind having wet feet and are good ol’ heavy feeders. Their job, after all, is pulling nitrites and ammonia out of the water before it goes back into the tank. Let’s see….I have a few pothos cuttings, three kinds of ivy, and a sprig of schefflera.
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All done! It’s been running for a week now with no problems at all. As you can see, the water pours into the tank, which made a very, very loud splashing sound. So I built a filter baffle to quiet the sucker down.
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Two weeks on and the filter is a complete success! There has been no leakage of any kind, the tank water is clear, and the water quality is high with no ammonia or nitrites to be seen. And, my favorite part, the plant cuttings I put in the top of the filter are growing like crazy! Check out the new little sprout off the schlefflera. Grow little friend, grow!
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9 thoughts on “Turtle Tank Bog Filter”

  1. Hi there. I don’t know how long ago it is that you made this filter or if you are even still checking this website, but your bog filter absolutely inspired me to want to build one of my own. From September to May, I foster diamondback terrapin hatchlings that are to be released into the wild in the spring. I recently released my last clutch and am now expecting another one come fall. So, I am making plans to make a bog filter of my own, because it’s just incredibly cool and I absolutely love all things natural. The only thing is that DBTs are brackish water turtles, so there is always a varying salinity in the water. I was just hoping that maybe you could give me some advice as to which plants to use and/or if it could even work in such a tank. Thank you for your time.

    1. Interesting! I don’t see why it wouldn’t work in a brackish tank. I’d look for plants that grow in brackish marshes. Pampas grass could be a good one. You may even find pothos to be somewhat salt tolerant. I’d test any you want to grow out by letting them sit in some of the aquarium water you use for a week or two.

  2. HA! You are awesome!!! You should definitely post on youtube if you do anything like this in the future. I sincerely enjoyed reading this. I have a painted turtle that I rescued from a parking lot back in the summer and I am try to learn as much as I can as he grows. I made the mistake of putting too much sand in his tank and I am just trying to keep things as natural as possible for him. I would like to have the water level fairly high and make a platform with legs for him to bask. I had a turtle topper, but I found that to be a pain to have on my tank. If you ever get the itch to make a diy turtle table/platform, I would happily see how you do so.

  3. hi

    How is the bog filter working out for you? I am interested in making one for my turtle tank but saw this post was from 2016 and i was wanting to know if your happy with it. Also what plants did you put in it? what is the filter rate on the filter?

    1. It’s still working like a champ! I’ve added a floss filtration layer to the bottom of the basket that the gravel sits in which helps grab any small debris and upgraded the pump that moves the water from the tank up through the filter up to an 89 gph pond pump. The plants that are in it are pothos, schefflera, syngonium, and philodendron, and when they get too big I trim them back and add the trimmings back into the gravel to root. If I went back and made it from scratch again, I’d go with wider diameter plastic tubing. It can get gunked up after months of continual use and I wish I’d gone with something bigger.

  4. Hi
    This filter looks great and I am about to embark on making one for my terrapin tank. I was wondering exactly what type of plants you put in the top of your filter.

  5. Hi
    Can you please tell me what plants you put in the top of your filter?
    I am looking to make one of my own for my turtle and aquarium tanks.

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