# [Wet Thumb Forum]-CO2 reactor for small tanks



## Hawkeye (Aug 20, 2004)

I have a 15gal tank that I am trying to get high light to work on (65w cf 9700K) But the problem I have is algae due to low CO2 levels SO what to do?

The tank is using pressure CO2 with a DIY bubble counter. From there it goes to a glass diffuser with a ceramic stone. I could not get the PH to drop no matter how much CO2 I pumped in. SO this tells me I have poor CO2 being dissolved or to much water turbulence at the surface. I think both.

To solve this problem I needed a filter I could submerge and all so use as a CO2 reactor. This is what I came up with. Duetto 100 submersible power filter.









They are really nice little filters. They work like a small canister filter. As you can see the water flow should give this small 15gal tank plenty of filtration.









Here are the parts. I will use the sponge but I have no use for the charcoal canister.









First thing to did is cut a ceramic air stone to a size that will fit inside the filter. I did this with a rotary tool and a course hard stone tool to cut and smooth the cut end.









Next I drilled a hole just big enough to push a 1/8 air line hose thru. I attached the air stone on one end and a 90 degree 1/8 air hose fitting on the other end.









Since I am not using the charcoal canister, that gives me room for the air stone.









Here is the final job. I have installed it today and so far so good. I will do a water test tomorrow and see if the PH has dropped any. It looks like its working. Once every few minutes I see some bubbles come out so its just a matter of get the CO2 bubble count to a level that will cut down on CO2 loss.







.

Just thought I would share my latest project with you guys. I'll keep you posted on my results.

Hawk


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## imported_BSS (Apr 14, 2004)

Nice pictorial and good info, Hawk (as always







). I have a similar sized filter for my 10g, but I really like the extra water flow path on yours. The one I bought just has water coming in the bottom and an undersized sponge directly under the impeller. I also really like the way you "integrated" the CO2 and diffuser. It should work out great.


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## Hawkeye (Aug 20, 2004)

Thanks BSS I just want to share what I have experience over the years so others might have it easier. Most Of my knowledge is from trail and error.

Looks like this is going to work better then I had hoped. My PH dropped form 7.5 to 6.8 . The bubble count is 1 bubble/sec. I still get the spurt of bubbles every couple of min. so I will cut back on the bubble count and see if I can still maintain a PH of 6.8 , which is my target PH level.

Hawk


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## StrungOut (Nov 8, 2004)

I used to just plug the tubing straight into this filter. After awhile gas builds up and the flow stopped working on me. Nowadays the filter for me builds up I don't know what gas and flow is gone, I think my impeller is really weak now, and my filter is really worn down. Just my experience with this filter. But the way you set it all up is very creative, and I'm interested to see how it works. I always thought this was the perfect internal filter, seeing your pictures makes me want to get this old guy back working again. Very interesting







.

Denny S.


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## cheesehazard (Mar 2, 2004)

Do they make one small enought for a 6 gallon tank? I just made a new shrimp tank and I need some new type of filter.


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## Hawkeye (Aug 20, 2004)

Yes I think they have two smaller filters. a mini 2-40gal/hour and DJ-50 12-60gal/hour.

Hawk


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## JamesHoftiezer (Feb 2, 2003)

Verry nicely done.

How is the airstone working out? I've been debating on trying one for CO2. I may also help people that are using no reacotor at all.

I've been debating on doing a similar thing. On my grow-out tank I have a circulating pump that also aerates. I've been thing about putting it in the bottom of the tank and piping CO2 to it.


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## Hawkeye (Aug 20, 2004)

I have all ways preferred the ceramic air stone to any of the wood stones. They last for ever and make the smallest bubbles. Thing seem to be working as planed. Its getting it set to the right bubble count. It looks like setting the bubble count to one bubble per sec. is going to give me PH 6.8. I can see my plants starting to perk up all ready.

Hawk


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## imported_russell (Sep 14, 2004)

does the mini version have the same flow structure? and also, whould it make a difference if i just get the mini? i would be using it on my 30gal.


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## Hawkeye (Aug 20, 2004)

I don't think this filter/reactor is big enough for a 30gal. On my 30gal I use a DIY external reactor that works great.

Hawk


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## imported_russell (Sep 14, 2004)

do you have a link to the plans for your diy reactor?


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## Hawkeye (Aug 20, 2004)

Russell
I'll take some better pic of it next time I get the camera out for some pictures. I have a partial pic of it in
http://aquabotanicwetthumb.infopop.cc/groupee/forums?a=tpc&s=4006090712&f=8006023812&m=8371034611

Its a very bad pic I'll get some better pictures to show you. There really easy to make and work very well.

Hawk


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## Hawkeye (Aug 20, 2004)

Well its been three weeks and I have a problem. Its not a biggie, here it is. Its time to clean the filter, to do so I have to take off the CO2 line running to the air stone. When I do this I will loose my pressure in my bubble counter. I wonder if I put a plastic in-line ball valve in the line if I can hold my pressure when I clean the filter. OR will I have to use a brass valve. I have run into problems with some of the cheaper plastic valves not holding up to line pressure.

Hawk


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## Aqua1 (Mar 2, 2005)

I think this is fantastic what you are willing to share.Hwakeye. I am having a 10gallon with 36 watt CF using Eco-complete and now I am seeing some brownish Algae on the Java Fern. I thought My CO2 was not getting disolve enough to lower the ph. I just might give this a try.


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## sarahbobarah (Sep 5, 2005)

Why do you have to clean the filter???


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## Hawkeye (Aug 20, 2004)

The same reason you clean any filter. They clog up with debris. I just have the sponge but it need to be rinsed out twice a month. 

Hawk


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## sarahbobarah (Sep 5, 2005)

Oh, duh!









I think I might be missing something here, though. Couldn't you just remove the sponges while they're still in the tank, and therefore keep the airstone under water?


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## sarahbobarah (Sep 5, 2005)

I actually saw this and made one myself. still pretty new, but works like a charm. Thanks for the diagrams. They were uber helpful.


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## Ben C (Apr 16, 2006)

i'm having trouble getting the co2 to dissolve before its spat out into the tank. What medium are you using Sarah? just interested. I currently have filter floss, but found that after a while the bubbles kinda make a path for themselves through the floss, and consequently make it to the impeller in pretty much one piece. 
Still gonna need some tinkering i guess.


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## sarahbobarah (Sep 5, 2005)

Well, since I work at a pet store, I can experiment with pretty much whatever is at my disposal. For the large Duetto filter, I've found that cramming ceramic rings into it makes the bubbles have to go through a lot of mini-paths before gettnig to the impeller, so it's kind of like using the Hagen CO2 ladder and then the impeller chops the bubbles up even more. 
The filter floss, if you're using the polyester teddy-bear stuffing typ, tends to disintegrate after time into a gross kind of sludge that clogs up the filter. 

Also, if you lay the Duetto on its side, the bubbles will take longer to go through it.


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## Hawkeye (Aug 20, 2004)

Any thing you can put in to slow the bubbles down will help dissolve more CO2. I haven't had this problem. I have dropped my PH from 7.8 to 6.8 and a CO2 level in the low 20s. With light at 2.4w/gal this is fine for me. I did notice this was the max level I could get no matter how much CO2 I pumped in. SO as Sara did you will have to do something to slow down and break up bubbles to increase CO2 levels.

Hawk


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## Ben C (Apr 16, 2006)

i think the filter that i am using is considerably smaller than the one you used hawk. I am still playing with the medium, but since adding a little more floss to the mix, things have started pearling in my tank. It still spits out bubbles occasionally, but i think i can live with it! its better than it used to be. 
thanks again Hawk


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## JaySilverman (Jun 19, 2005)

That works perfectly. I use the same idea. But my sub.filter is a the small Fluval 1 by Hagen. It disolves about 85% of my co2 at 1 bubble per 3 seconds. It burps out a bubble every now and then but no biggie.


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## sarahbobarah (Sep 5, 2005)

Has anyone else had a problem with the filter sucking in the yeast mixture from the pop bottle? It did that to one of my tanks.


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## Hawkeye (Aug 20, 2004)

Use a 12oz plastic bottle for a bubble counter. If you have any yeast leaking it should be caught in the bottle before it reaches your tank. I use pressure tank CO2 now but it the past when I use DIY CO2 I used a bubble counter as a save guard against yeast dumps. 

Hawk


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## TommyBoy (Jan 9, 2006)

I like your idea Hawkeye. ANd since imitation is the best form of flattery...

Besides the Duetto I am looking at 2 others:
1) Hagen's Elite Mini filter (http://www.hagen.com/usa/aquatic/product.cfm?CAT=1&SUBC...OD_ID=01001300021501)
2) Zoo's Micropump [Model 104] or modifying the filter version [Model 304] (http://www.zoomed.com/html/aquatic_pumps.php)

However, I am a DIY CO2-er (still), and reading of people creating unwanted / too much sucking pressure on their DIY/Yeast CO2 from using powerheads as part of their diffuser/reactor set up (here in this forum and elsewhere) makes me concerned.

One idea I have to compensate for this problem is simply to use the old internal reactor design that attaches to a Rio or pump with an airline. Another is separating the CO2 diffuser from the powerhead/Duetto/etc. So the diffuser would end up a few inches below the pump/powerhead.

Any thoughts? ...qualms? ...considerations?

TIA,
--TommyBoy


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