The Built-in DIY Filter
Disclamer: the following was written almost a month ago. As I was waiting for the aquarium I needed to come into stock I didn't want to post anything as there was a risk it could take weeks, I didn't want to find that this topic was left seemingly abandoned while I waited to be able to make progress.
I wanted to start this journal to document a mini DIY project I’m attempting. The project is to modify an aquarium and build a filter into it; by doing this I hope to maximize swimming room for the aquarium’s future inhabitants and keep things as aesthetically pleasing as possible. The manner of filter I’m creating will offer minimal amounts of suction and water agitation whilst still offering superb filtration and so it is, in my opinion, ideal for a betta tank.
The entire project is somewhat more complicated than it honestly needs to be but complication keeps my mind occupied for longer, it also allows me to check for flaws better (in my opinion at least) should I ever reattempt the project on a larger scale. My planning allows room for mistakes but should this entire project fall through the aquarium I use will still be functional.
This project is centred on a 30 x 30 x 30cm glass cube that holds approximately 27 litres (5.5 gallons) of water, it will be Kaze’s future home. The cube is the exact same size as Echo’s (my other betta) and is a very attractive tank, it is also much larger than I originally thought (I believed it to be between 21 and 24 litres but this has since been proven false) and is at a size I am completely comfortable with. Once this project is over I will be planting the aquarium and will continue the journal for a brief time to study how well the filter functions.
The filter I’m looking to build is known as a moving bed filter, it’s an extremely simple design that works off the principle of survival of the fittest. The most basic design for a moving bed filter (and perhaps the easiest example used to explain how it works) is a plastic bottle with tiny holes drilled in the bottom and larger holes drilled into the top. Through the cap of the bottle an airline is fed and on the end of the airline is an air stone or an airline “T” junction. Air is then pumped through this; the invading and released oxygen encourages water to be sucked into the bottom of the bottle where it then escapes out the top (similarily to a sponge filter).
Before this can be an effective filter the bottle needs to be filled part way with filter media, many people use ceramic balls or serrated plastic pieces – the more surface area the better. Once the air is flowing freely through the bottle it juggles the lightweight media around, causing each piece to bump into each other. These collisions are believed to force the beneficial bacteria that will form on the filter media to re-establish itself regularly so only the strongest survive. This strong bacteria is then believed to be more effective at consuming ammonia and nitrite than your standardized static bacteria found in non-moving filters with filter sponges.
These filters are often found to be used with koi ponds and fish farms.
I made this random diagram in an attempt to show how these things work… I er… hope it doesn’t confuse anyone.
While the project itself seems complicated the actual design is very simple. I intend to use a small sheet of plastic (perhaps styrene or Perspex, depending on what is available) cut to an appropriate size and drilled as required, I will be siliconing this into the back corner of the aforementioned aquarium with the airline and relevant accessories. I suppose the fun is in the planning and taking photos.
I will be using:
* A 27 litre/7 gallon glass cube aquarium
* A sheet of plastic cut to size with appropriate holes
* Geocel brand aquarium sealant/silicone
* Silicone airline tubing
* An airline “T” junction
* Airline tubing grip suction cups
* A random drill
My filter media of choice is known as HEL-X, it is a serrated plastic wheel. I prefer plastic media over ceramic as ceramic will likely break down due to the continuous movement and collisions it would be subjected to.
I am not, nor will I ever claim to be the one who came up with the moving bed filter idea. I simply think it’s a wonderful filter and wish to utilize it in an efficient and space-saving way. I discovered a video regarding making a moving bed filter on YouTube and thus my curiosity was peaked – you can search for moving bed filters on YouTube to find various videos on how to make your own in a very quick, simple and cheap way.
One question I may be asked is “why build the filter into the aquarium and not use the bottle method but hide it behind some plants?”, this question is a very good one. My reason for wanting to use a thin sheet of plastic in the corner of the aquarium is to make a narrow corridor leading directly upwards, my hope is that due to this smaller space the oxygen released by the airline “T” junction is spread more evenly thus giving better movement of the filter media. I would also find this corridor a lot easier to maintain should I need to add or remove media as it would lead directly up towards the lid of the aquarium whereas a bottle would need to be completely removed and the cap undone.
Please be aware that the main "journal" part of this topic was started last month, I decided to hold off on uploading what I'd done so far as I was unsure when I would be able to acquire the second aquarium and didn't want to find I had no updates for weeks after starting.
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Things are gradually coming together! I will definitely update, probably tomorrow (the piece of plastic is the right size now)!
