DIY CO2 reactor/surface skimmer

Tug

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* The Duetto is no longer manufactured, Post #14 explains the work-around for modifying the Fluval Nano filter.

To modify the Duetto multi filter to perform as a surface skimmer.

I had a few of these filters when I decided to add CO2 to a 20t. Lighting was bright in this tank, 360mml PAR at least, from a large window, as in the full length of a south facing wall, 7floors up, bright light, with two T5's over the tank. For high CO2 demands such as this, I used 2 x 1 gal. diy yeast generators. I used only one successfully for some time, but maintenance is easier with two.

For the reactor, all the parts are interchangeable for both Marinland filters, so I scavenged the DJ100's larger impeller to use in the DJ50's smaller filtration housing.

Tools for this project are;
  • needle nose pliers
  • a flat head screwdriver
  • any drill, auger or power drill
  • and one insert coupling, (little black thing that comes with the filter).
    Be resourceful. Crush off an old air stone ceramic cover (using the little plastic thingamabob inside)​
    Or, just stuff the air hose in the opening.​

First:
  • This modification allows water to flow in the direction you want, positioning the filter's intake vent parallel to the water's surface as the filter attaches horizontally against the tank. This allows the pump to work as a surface skimmer and/or allows CO2 to gas off in a case of EOTD or when yeast is gassing off CO2, but the pump is turned off.

Horizontally, as in...
LiWei9BM_800x711.jpg


The filter's suction cups are designed to be placed on either side of the filter with just the removal of two punch outs. Use the screwdriver to pry off the top of the lid and remove the tabs. Then, move the suction cups from the original position to their new home, allowing the filter to be used as a surface skimmer/aerator. Of course, if the filter already faces the way you want the water to flow and the suction cups are were you need them for the surface skimmer to work, move on to the next step. :untroubled:​
 
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Tug

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So easy!

Second:

To make the reactor;

  • Using a power drill or hand tool, drill an opening to the largest chamber, directly across from the impeller.

    :confused: Where?
    Say, the pump were to stand vertical, pump on top.
    Drill the hole in the bottom of the clear filter housing into the largest chamber.​


Just enough of an opening for your fitting or hose to attach.

Now that you have an opening for a CO2 line.
Snap the filter back together, insert the CO2 line, check valve and your good to go.

P9090039.jpg


P9090040.jpg


P9090036.jpg
 
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Philosophos

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Nice adaptation of the powerhead/needlewheel concept. Have you bothered to do anything with the impeller?

One thought; if possible, try to modify the output to get lower down in the tank. I love the idea of it as a skimmer, but sending the CO2 enriched water down as low as possible would probably help with the diffusion efficiency.

-Philosophos
 

Tug

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Most of the CO2 diffuses into solution. There is a small pocket of air that stays in the chamber.
I notice micro-bubbles at fairly high gas rates if the air pocket is big enough to be sucked into the impeller.

When the pump is turned off by the timer, CO2 in the main chamber gasses off through the intake vent.
With the CO2 off, it can run at night as a skimmer.
 
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Philosophos

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The small pocket of CO2 is no big deal unless it's interfering with something.

I think I'm using a powerhead of a different brand, but identical manufacturer for most of the components. Parts of yours look like a ViaAqua mini. If it's the same impeller, I believe tom rigged up a brillo pad glued to the top of it. This may take care of your CO2 bubble as well.

Someone over on APC mentioned drilling/melting small holes in a finer impeller on a thread I'm posting. I think it's mentioned on the needlewheel thread here as well. Maybe that'd be worth a shot as well?

-Philosophos
 

Tug

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Counting Bubbles

The DJ100/50 provides a clear view of the bubbles as they enter the filter housing - a bubble counter.

When the pump is running it creates a negative pressure pulling the CO2 into the chamber.
For tanks of 30 gallons or smaller expect high levels of CO2 with a relatively low bubble count.
The DJ100 reactor housing is able to handle a steady stream of CO2 with little effort or noise.

[video=youtube;RH4Po_gSNCQ]http://www.youtube.com/watch?v=RH4Po_gSNCQ[/video]
 
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Tug

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What's to Like...

  • A small and efficient reactor for diffusing CO2.
  • Easy to make with simple tools.
  • No need for a bubble counter and a relatively small size powerhead, behind the plants. :chargrined:
  • The CO2 line attaches to the filter in a way to create a venturi effect.
    :torn: This pressure difference in the line is very helpful w/diy sluggish fermentations.​
  • Easy to clean when a yeast/DIY is providing the CO2.
    :semi-twins: Yeast is messy, fouling lines and check valves.​


Cons:
  • Suction cups can release the filter, allowing it to sink to the bottom of the tank.
    I avoid this by securing the power cord once the pump is in position.
  • Marineland could use the same impeller in both the DJ100 and the DJ50, but they don't.
  • The pumps have become more expensive.

 
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Biollante

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Good Job!

Hi Tug,

That is a nice set-up and good application. :)

I have found the ‘Brillo Pad’ option is very effective. ;)

Biollante
 

DaBub

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I use the same arrangement in my planted brackish aquarium. It works well.

Foucault's Pendulum?
 

Tug

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An intellectual adventure story

Foucault's Pendulum, written by Umberto Eco.
The description of the pendulum at the abbey church of Saint-Martin-des-Champs is mind-blowing and the book just gets better.
 
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Tug

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Here is a less verbose description of the modifications. :surprise:

1. Remove all of the filter pads and bio balls that come with the filter. The filter chamber should be empty.

2. Drill a small opening for the CO2 line into the largest chamber of the main filter housing.
Use a small air intake adapter to attach the CO2 line. A small elbow fitting works best.

P9090040.jpg


The filter is then attached to the side of the aquarium glass,
parallel to the waters surface with the filter intake facing the waters surface.

34360a25-1d23-4d77-a6f7-fe4e25601728.jpg


In this picture the filter is being used as a skimmer. For CO2,
the filter is placed lower in the tank but the position of the filter intake is the same.


3. This last step is for when you need to move the suction mounts, to position the filter.

Remove the aqua-sweep outlet and pry off the top. All this is easily understood when looking at the filter.
There are two tabs that can be removed. This allows the suction mounts to be placed on either side of the filter.

b21b347c-c43e-403d-82f2-ae1c31f723b5.jpg


I am using this diy on a 30 gallon tank with good results.
It did require careful placement and adjusting surface ripple but most CO2 methods require this anyway.
 
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Tug

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Thanks Matt,
Unfortunately, Marineland no longer makes the Duetto multi filter (the sponges needed daily cleaning to prevent loss of flow) but Fluval makes a filter almost identical to the D100 for around $22. This is a good thing because I've gone through my available stock trying to improve this little reactor. There's one work-around when modifying the Fluval nano filter and I'll be posting it next but first, one additional modification is needed to make both filters even more efficient reactors.

The original modification could drop my 4.5 dKH water from a pH of 7.4 to 6.6 in about 2 hours.
This next modification dropped it to a pH of 6.4 in 1.5 hours.
_DSC1900.jpg

API kit was used for determining pH & dKH.

All of the previous modifications are the same except,
another hole is drilled into the filter housing and the CO2 line is attached to this new opening using an elbow fitting.
The filter is then placed upside down into the tank. The filter is about 8" long so you will need a fairly deep tank to run it this way.
_DSC1895.jpg
_DSC1896.jpg


They still work sideways but more efficient run upside down.
The filters have three chambers in the filter housing.
The second hole drilled is into the area of the middle chamber about an inch from where the filter comes apart.
_DSC1897.jpg


The original hole drilled into the bottom of the filter housing now allows the chamber to fill with water but won't let CO2 escape while the filter is running. This makes it an excellent reactor to use with yeast powered CO2 generators because it provides a way for gas to exit the filter when the pump is off. For pressurized CO2 systems the upside-down position provides additional dwell time in the reactor and a second layer of security should the solenoid valve stick open the CO2 just bubbles out to the surface until the pump turns on again.

[video=youtube_share;a3BNkdBrhPE]http://youtu.be/a3BNkdBrhPE[/video]

In the video I have placed the filter out in the open for easy viewing. Otherwise, it can be placed anywhere to provide the flow pattern you prefer or to reduce it's profile as you like. The bubble count in the video is a little high compared to the output of most yeast CO2 generators but I should get about a year out of a 20lb CO2 tank. And, for someone just starting to add CO2 this a is quick and easy DIY reactor perfect for yeast run generators.
 
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Tug

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Fluval Nano Modification
This filter might not meet the low cost requirement of most DIY projects but it does offer a needle-wheel/reactor option for CO2 users, for around $22. I have not tested the Fluval but the bubbles that come out of the Duetto filter act very much like water and most never make it to the waters surface.

I decided to post the modifications because they are both quick and effective. Well that and the possibility that someone's Marineland Duetto was sitting in a box of junk until a time when lemonade could be made out of their lemon.

Unfortunately, Marineland stopped making this filter and our source for lemons dried up. Time for an updated version.

Enter the Fluval nano filter. Placed under a pile of oak leaves for over two months it was still circulating water.
So, it's not a bad little filter and should be around for some time.

Seen in the following picture, the filter has a removable center partition for easier cleaning. This also makes it easy to reach when modifying the large opening on the far end.

So, to modify the fluvial follow the previous Duetto modifications. Next, a 2.5" by 1.25" piece of plexiglass is added to the removable partition, restricting the flow of CO2 entering the main chamber. It should fit snug - you shouldn't need glue.
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