# DIY CO2 with HOB filters



## Gatekeeper (Feb 20, 2007)

What "CO2 indicators" are you using?

To be honest, the HOB filters do create some surface aggitation which could degas some of the CO2, but to be honest, as long as its not a huge splashing episode, you should be ok. I know plenty of people who have HOB on planted tanks and CO2 and not many will cry over off gasing.

Don't get me wrong, there is certainly some validity to it, but in my opinion, this is one of those "internet wives tales" that has spun a nasty spell on everyone.

So, lets focus on what your indicators are and what we can do to rule out the HOB first.


If you are really concerned though about the HOB splashing the water, put something below it to keep it from splashing. Any kind of plastic can work by propping it underneath the HOB outfall.


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## lainealex (Sep 27, 2009)

I am using Red Sea indicators with 4DKH water from Greenleaf Aquarium.

The HOB are not splashing, they are just agitating the water surface. The reason I think it's the HOB that are causing the problem is that when/if I turn them off, the CO2 indicators turn green.

Lainey


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## Gatekeeper (Feb 20, 2007)

lainealex said:


> I am using Red Sea indicators with 4DKH water from Greenleaf Aquarium.
> 
> The HOB are not splashing, they are just agitating the water surface. The reason I think it's the HOB that are causing the problem is that when/if I turn them off, the CO2 indicators turn green.
> 
> Lainey


Then you need to focus on getting rid of the surface agitation. Trying something like I proposed may help.


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## lainealex (Sep 27, 2009)

Is there a way to beef up the CO2? Could I use a larger bottle say 4 litre? Or is the amount of CO2 going to be the same coming out of the diffuser regardless of the size of the container and the volume of sugar/yeast solution? For some reason, I can't wrap my head around how that works. Would making a stronger CO2 recipe work somehow? I do think adding another bottle and another diffuser would work, but I'm not too interested in that. 

I can't quite see how I'm going to adjust my Aquaclear HOBs with a plastic piece but I'll try to think of a way...

Thanks for the help...

Lainey


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## i love planted tanks (Apr 27, 2008)

ya,i have HOB filter on my 46gal bow and using diy co2 just for right now to make the plants grow in faster.and plants are growing fast and healthy you just got to have the water above the out take water fall area and you will be good,in my tank i just have ripples from the HOB filter barley looks like any surface breakage


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## i love planted tanks (Apr 27, 2008)

lainealex said:


> Is there a way to beef up the CO2? Could I use a larger bottle say 4 litre? Or is the amount of CO2 going to be the same coming out of the diffuser regardless of the size of the container and the volume of sugar/yeast solution? For some reason, I can't wrap my head around how that works. Would making a stronger CO2 recipe work somehow? I do think adding another bottle and another diffuser would work, but I'm not too interested in that.
> 
> I can't quite see how I'm going to adjust my Aquaclear HOBs with a plastic piece but I'll try to think of a way...
> 
> ...


and yes you can have multiple diy co2 2L(or any other size bottles) to increase co2 in the water


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## lainealex (Sep 27, 2009)

I have the water up above the HOB outlets, but I can't eliminate the agitation. When I turn off the filters, the CO2 indicators go to green but when I turn the filters back on they go to blue again. I think I need "more" CO2. 

The other thing that works to get the indicators to green is to add Excel, but I don't like to use Excel.

If I use a larger volume of CO2 sugar/yeast liquid in my bottle, would this give me more CO2 coming out of my diffuser? Or would I need to add another diffuser with another DIY bottle? What about a "stronger" recipe for the DIY bottle that I already have?

Thanks!

Lainey


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## Nymsley (Mar 24, 2009)

Excel shouldn't cause a color change with drop checkers, its not CO2.

A "stronger" recipe implies at more yeast is added which would increase the initial production but it will cut into the duration of the mixture. It would be better to just add another bottle. Having it go to the same diffuser or another one is up to you.


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## sparkysko (Jun 11, 2004)

I had CO2 to yellow injecting it into a powerhead. I changed powerheads, and it's in the blue again. I also have surface agitation with a HOB. I'm going to go to the brew store tomorrow and pick up a 5 gallon container and champagne yeast. From other reports it'll last up to 6 months.

I'd suggest just adding more bottles.


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## Stasiu (Sep 9, 2007)

I had a 10 gallon with a full HC carpet that died off when I put a HOB filter on it. All I had before that was a small power head to circulate the water, no other flow/filtration. One thing I was able to do to decrease the surface agitation with the HOB filter is cut a filter pad so that it was wedged on the overflow and the water kind of flowed through it.


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## jreich (Feb 11, 2009)

sparkysko said:


> I had CO2 to yellow injecting it into a powerhead. I changed powerheads, and it's in the blue again. I also have surface agitation with a HOB. I'm going to go to the brew store tomorrow and pick up a 5 gallon container and champagne yeast. From other reports it'll last up to 6 months.
> 
> I'd suggest just adding more bottles.


 i second adding more bottles. run them both threw the same difuser or powerhead. a 5 gallon bucket of yeast should last you a lifetime!i have a 1lb brick of yeast, and have bin using it for a year now and i'm only half way threw it.


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## Hoppy (Dec 24, 2005)

In a planted tank the filter helps circulate the water in the tank, and it removes fine particles that otherwise give you cloudy looking water. Both of those functions can be done by a small powerhead with a sponge on it, or one of the small in-tank filters, which is basically a powerhead with a small filter media chamber attached. Then, you can use that method of filtering to also be the CO2 reactor - kill two birds with one stone. I found I much preferred having to try to hide the in-tank filter to having the hang on back external filter in the way all of the time. And, you waste less CO2 if you use the in tank filter to chop up the big CO2 bubbles into microscopic bubbles.


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## talontsiawd (Oct 19, 2008)

Gatekeeper said:


> Don't get me wrong, there is certainly some validity to it, but in my opinion, this is one of those "internet wives tales" that has spun a nasty spell on everyone.


I just want to reiderate this point. Outgassing is minor. Don't get me wrong, there was a noticeable change at night for me but my BPS didn't change much to get my drop checker to green. It is minimal and should not stop you from being sucessful. 

If you really feel it is a problem, I would recommend an internal filter, or better, a canister filter. But at that point, it almost seems better to invest in a pressurised system where you can easily overcome your issues anyway and it is a lot less work. 

You may also want to upgrade your diffusors, I haven't heard great things about what you are using. Or try a different method all together.


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## mikinct2 (Jan 18, 2017)

lainealex said:


> I am struggling with two tanks that have two litre bottles of CO2 running strongly through Red Star diffusers. One tank is ten gallons, the other is 20 gallons. Both tanks have HOB filters and I think the filters are releasing the CO2 when they break the water surface. Filling the tanks to the brim doesn't help.
> 
> I can't get my CO2 indicators out of the blue zone. My CO2 flow seems strong, and I have tried different recipes - nothing seems to help.
> 
> ...


If I leave media & sponges in HOB Filter, will the C02 going into my intake make it through the filter media & into my tank for the plants or be wasted getting diffused only in the filter area.


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## Tvadna (Jan 17, 2013)

Use a small piece of filter floss cut the width of the outflow of the HOB filter. Cut it long enough so that you can wedge it between the filter and the media to hold it in place and also long enough so that it barely lays into the tank. This cuts the surface agitation to nearly zero. 
You're not crazy Lainey, this does boost the CO2 in the aquarium a small amount. Just because your drop checker is blue, doesn't mean there isn't any CO2 in the aquarium. If you're using low light plants have have low lights, they won't use much CO2 anyway. Find a balance that works.

You can also add a bottle or get a larger bottle. If you have two bottles, you just connect them with a cheap airline Tee fitting. 
If you want your mixture to last longer with DIY, order some champagne yeast. They have a higher tolerance to alcohol(which is the waste they produce and eventually kills them) then bread yeast. That way when you make your new batch with the champagne yeast, you can add more sugar and it will be used before the yeast die off thus lasting longer. 

Feel free to message me if you have any questions or want me to send a picture of what I'm talking about.


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## GrampsGrunge (Jun 18, 2012)

Honestly many. many years back I used 2 liter DIY yeast bottle CO2 injection systems on two tanks.

One each in either a DIY bell-jar, with a special outlet off my ancient Metaframe DynaFlo, that swirled water underneath it, or the Hartz Mountain HOB on my 32 gallon, which I just drilled a hole in the long outflow pipe from the impeller and it blew CO2 bubbles down the length of the pipe while the turbulence broke up the CO2 bubbles before it reached the return. Neither of these two filters did much in the way of surface disturbance like modern HOB filters do. The third tank had a AquaClear with no CO2 and it almost grew plants as well as the other two.

I'm still of the opinion that you don't need a lot of CO2 to grow plants well, I think an active, healthy substrate and micro-nutes on a regular monthly basis, for a proto-low tech tank.


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## dkraft12 (Sep 26, 2016)

DIY co2 IME will never get you close to a bright green indicator. Even if you can get it flowing very fast, it will run out quickly. Switching to pressurized was the best thing i've done since getting into planted tanks. I use a 20oz paintball bottle and aquatek regulator with solenoid that goes for about 100 bucks(meant for paintball tanks). With this you can just increase how much you inject into the tank until you find the sweet spot. Startup cost is somewhat high but is well worth it in the long run. I have to run 4-5bps to get a 35ppm during the day because i also have a hob filter and i assume a lot of it gases off. Still, a 20oz tank lasts 3 months and i get them refilled for $5ish dollars at dicks sporting goods. Also, the nice thing about Paintball is it doesn't take up any more space than a 2 liter bottle of pop


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