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Custom Nano Filter Design / Material Question

NayrP

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I am looking into getting a Nano Cube 10-20l for a small corner in my living room and haven't had much luck finding a small enough external filter. I don't want an internal filter or a HOB for astetic reasons and was looking for something that looks nice that I can put on the table next to the tank. The engineer in me said to just design one, so that is what I did. The idea is similar to your typical canister filter where the water inlet is on the bottom and the outlet is on the top. It uses a small 200l/h pump and has two baskets for sponges / biological media on the inside. I am thinking of making the body of stainless steel. Has anyone had any experience using stainless steel in an aquarium? I thought it would look great and shouldn't have the corrosion problems that come along with other materials. What do you guys think of this idea? Any design suggestions from your previous experiences that could save me some headaches down the road?? The filter is 17 cm tall and has an outer diameter of 8 cm, so it should be big enough for a 10-20 liter tank (definately more space for media than an internal filter) but still small enough to fit on the table next to it. Here are a few renderings of the idea (I didn't model the threads just to save some time)

Let me know what you guys think!
Ryan

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Nick potts

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Very nice renderings.

Stainless is fine, there are a few stainless filters about (ada etc).

I have no idea how much time and money something like this would cost for you to make, but I would be more inclined to ask these guys about shipping one to you as there filter is pretty much exactly what you want and nearly the same size.


 

noodlesuk

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Very nice renderings, like the design. It's very hard to find a small elegant external filter, I had a look for my nano and decided to stick with the internal filter in the end.

Also might need some banjo type connectors, if not in use already. Sods law says that when you tap the threads and screw in the hose connectors, they tighten up, facing the wrong way!

What pump have you used? I started looking at making one too and could only find external pumps, bought a nice mini Eheim one, but looks better integrated. The ADA one looks a bit agricultural, with its external pump.

Stainless 303/314/316 would be best, 303 is easier to machine. All very expensive to do, but will be nice. How does the top secure? Cost could be reduced if you use a standard SS large bore tube for the middle and make custom caps, maybe, might work out.

Great project, will look forward to updates.
 
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noodlesuk

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Why not put a small pump in the aquarium and pump the water to a canister outside

Couldn’t you adapt a flask of a ss water bottle

This would keep the costs down


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There's quite a few projects online and YouTube using flasks or storage tins. Problem is the wall section is so small, can't get a decent thread for the couplings. Needs bonding , some sort of back but flange or welding (like ADA). Some guides seem to rely on a connector self tapping, which is never going to stay water tight after a few knocks in use. Also difficult to get the modded flask designs to look good, always look a bit too DIY imho.
 
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NayrP

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The plan is to use 316L stainless for the main body and the cap. The cap is threaded and screws into the body (the lowest diameter that seems to overlap is threaded) and it all seals radially with the shown o-ring. I picked couplings that use a tapered thread so I should have some wiggle room with the positioning.

That small filter is pretty great. The only thing that I don't like is the pump on the outside. Since I am going to be sitting right next to this thing all evening the goal was to make it as quiet as possible. So my design uses a small submersible pump that is mounted to the inside of the cap to contain the noise within the filter and a gland to route the cable out and seal it from leaking. The whole filter sits on a rubber pad to dampen the vibration from the table it sits on. I will keep you guys posted as the first parts start to arrive.

The CO2 idea is also interesting! Will have to keep that in mind. Going for something low tech for this cube but if all goes as plan maybe an upgrade in the future!
 

noodlesuk

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The plan is to use 316L stainless for the main body and the cap. The cap is threaded and screws into the body (the lowest diameter that seems to overlap is threaded) and it all seals radially with the shown o-ring. I picked couplings that use a tapered thread so I should have some wiggle room with the positioning.
Nice 316L, only the best, will be expensive, or are there some offcuts lying around at work ;)

The threaded cap keeps it nice and simple, but will be a pain to unscrew, with hose & power connected, but I guess your hoses could be removed from the tank as only short, but would flap around a bit. Or could fit quick disconnect couplings, something like this:-


Or inline

 
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Big G

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Looks amazing.
Would have loved to have gathered the skills to fabricate. Must be very satisfying.
Beats the hell outta driving a desk for living.

Best of luck 👍

Bg
 

NayrP

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So I have decided to do a small redesign based on all of your suggestions! Moving the pump to the bottom, having both the inlet and outlet connectors on the base so that the cap can be more easily unscrewed and adding a connection for a small CO2 diffuser which will be mounted inside of the filter body. Will post some updated renderings as soon as I have some! Thanks for all of the great tips thus far!
 

NayrP

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Here's a quick update on the new design changes. Inflow is now located on the top and outflow on the bottom. Both hose connections are located on the body of the filter to ease removal of the cap during filter maintenance. An additional cap has been added to the bottom to allow access to the pump during installation. A bleed valve has been added to the top cap in order to help with priming and removal of trapped air after maintenance. An AQUARIO Neo Mini CO2 diffusor has been added to create smaller bubbles in the filter to hopefully increase the speed of CO2 dissolution into the water. The pipe can easily bent as it is made from acrylic and can be sealed using a cable gland just like the electrical cable from the pump. The only thing missing still is a small pipe which will connect to the inside of the inflow hose connector to direct the water flow upwards to help with mixing the CO2 into the water and prevent it from collecting at the top. Here are a few new renderings to show you how this will look. Let me know if you guys have any other suggestions before I start on the parts! Pump mouting bracket and the grid plate on the bottom are to be 3D printed out of an aquarium safe material yet to be determined. On top of the grid plate (from bottom to top) will sit a layer of bio media followed by a thin layer of filter floss and then a more porous sponge to help prevent clogging of the bio media and the pump.
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Having right angle connectors for the inlet/outlet hoses can seriously affect the flow. If you look at the Eheim classic and ADA filters the bottom hose connector has a nice sweeping curve to it. You can buy the Eheim part as a spare so no reason not to use it? A straight connector on the top of the canister would also be better in terms of flow. Having a removable media basket will also make cleaning much easier. I like the idea of a nice stainless cylinder though and though I’d quite like one myself. The biggest issue I’ve come across with external filters of late is one of noise from the impeller, it can be extremely irritating! I look forward to seeing what you come up with.

Edit: when I first considered making one I thought of using an existing container to save cost.
 

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Wookii

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Beautiful renderings @NayrP , some superb CAD skills there - I assume you have access to CNC machining to make these parts? They're are not possible from standard fabrication materials (tube and plate).

I like the inclusion of the CO2 diffuser, however I would personally have the inlet in the centre of the lid. you will invariably get CO2 build up at the top of the canister, and if the inlet is in the lid, that trapped CO2 will get constantly diffused into the water by turbulence like a typical CO2 reactor.

If I was designing a filter from scratch myself, an easily removable pre-filter would also be a requirement for me. I would also suggest some taps on your inlet and outlet nuts, so you can clean the filter easily without having to break the inlet and outlet syphon.
 
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noodlesuk

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Looks great, nice to see the evolution. I like the use of the Radiator bleed valve on the top. Is the lid biased (conical) so any bubbles collect towards the bleed port?

If you want something that might be easier to connect to, other than the Neo diffuser, maybe a sparge might work. These are used in labs for dispersing gas, like an air stone, but can be threaded to allow easier connection. I've never used one in an Aquarium, so not sure how efficient it would be in terms of bubble size. You can get sintered, glass, PTFE, PEEK variants, something like <Sparger> . Or even a Pneumatics silencer could work <Silencer>. Or just stick with what you know, if you don't want the extra hassle!
 
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These are some of the Eheim spare parts available.
 

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noodlesuk

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These are some of the Eheim spare parts available.

Be interesting to see the loss of the 90deg Elbow vs the Swept 90Deg, for the sake of aesthetics and keeping all parts (and threads) standard, I'd probably keep the current design, unless the pump is already struggling. There is some info on the effect of different bends here <Resistance Of Fittings>, assume fittings are around 12mm, effect of elbow vs swept is the equivalent of 400mm of extra hose. I always found those Eheim curved inlets a bit fragile, so much bend hanging out to allow leverage against the thin wall threaded section, which will also be in Stainless, so less forgiving.
 
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I also wonder if sharp bends will accumulate the inevitable build up of dirt quicker, particularly in those tight corners? Cleaning them would also be much harder. From past experience the gentle sweep of the Eheim bends are easily cleaned with a hose brush.
Some more thoughts. It’s a lot easier to fit seals on a flat surface like the lid rather than the curved walls. The later render looks a bit messy with those seals on the side IMO as well, but that’s personal.
 
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NayrP

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I had the same thought about the 90° elbows causing some flow loss but there were a few reasons for choosing them over the Eheim or other similar plastic bends. Number one was space savings. The Eheim bends have a radius of ca. 40-50mm (which puts the hose approximately that far from the body of the filter) whereas the 90° elbows allow the hose to sit only 12,5 mm away. When you think that the entire filter has an outer diameter of only 80mm that makes quite a difference. The next reason is positioning. The 90° Elbows have a tapered thread which gives me some wiggle room as far as positioning goes when tightening them into the filter body. With a plastic thread which seals axially to the body the thread needs to line up perfectly to ensure that the inlet/outlet pipes sit how I need them to sit and won't leak (something that is more easily done with a plastic body than a metal one). The pump that I have chosen does 200l/h and in a cube with probably 15L of water after substrate, hardscape, plants etc. I should be alright as far as flow goes even if I have 25% loss due to plumbing (still puts me at or just below that magical 10x turnover per hour).

The pump is mounted to a plastic bracket and has a layer of silicone between itself and the body of the filter. I think this should do a pretty good job of minimizing noise/vibration. The whole filter also sits on a rubber pad to help with vibration noise transferring to the table that it sits on. A media basket is also something I had in the first version of the filter. I am planning to try it first without one but if it turns out to be too much of a pain I will add one later. A sparge is a cool idea for injecting the CO2. Will have to look more in to those maybe for the future. The nano diffuser is already on the way. Will see how that goes and can adjust if necessary.

Here is a quick render of the filter with a 40mm bend radius pipe vs. the current 90° Elbow. Think this shows the difference pretty well.

Bend.jpg
elbow.png


PS: Thanks for the input!!
 
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Another random thought!? Many filters rely on the water flow to expel trapped air - rocking the filter whilst it’s running aids this. I’m not sure what problems you may encounter if the water flow is out of the bottom of your filter?
 
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