# DIY CO2 Diffusion via Aquaclear HOB - Learned something interesting...



## kidgrave (Feb 4, 2014)

Thank you so much for the interesting advise that you shared. You have a really nice tank, so keep up the good work. Just wondering, what is the name of the plant all the way to the right?


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## burr740 (Feb 19, 2014)

kidgrave said:


> Thank you so much for the interesting advise that you shared. You have a really nice tank, so keep up the good work. Just wondering, what is the name of the plant all the way to the right?


Thanks. The far right plant in front is regular Baby Tears - http://www.plantedtank.net/forums/myPlants.php?do=view&p=73&n=Baby_Tears_Lindernia_rotundifolia

So far it has been an absolute weed, a gorgeous weed, but man does it grow fast. Those pics were taken 2 weeks apart.

Behind that in the far right corner is some kind of sword Ive yet to identify. First thought it was a Rubin or Osiris but it's not turning red, so idk.










Im about to rescape this whole tank. Some of the larger stems are going in my 75. Thinkiing about moving the Baby Tears to the left rear corner, along the sides and back. The right side will open up, the HC can continue to spread all the way across and the sword'll be visible.


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## cordova (May 30, 2014)

burr740 said:


> ...So anyway, I thought this might be usefu l for anyone using HOB filters, powerheads, etc to diffuse their DIY CO2. :icon_wink


Under what conditions would the CO2 aerate out of the water when going through the filter?


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## burr740 (Feb 19, 2014)

cordova said:


> Under what conditions would the CO2 aerate out of the water when going through the filter?


Not sure I understand the question? 

I dont think a cartridge-type filter would be very efficient due to the open chamber between the propeller's output and the filter media. After leaving the propeller chamber, a good portion of CO2 could gas out in the open surface area there, before getting drawn into the media. 

Aquaclears are designed so that isnt the case. Water from the intake is forced straight into the lower sponge, and goes up from there, passing through all stages of media. There is no in between area with an open surface like a cartridge filter.


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## dru (Mar 9, 2013)

How has the impeller held up over time?

Great tank BTW!


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## jrill (Nov 20, 2013)

Ummm. If you can see the bubbles coming out even if its a mist doesn't that mean that your not getting the diffusion you should?


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## burr740 (Feb 19, 2014)

jrill said:


> Ummm. If you can see the bubbles coming out even if its a mist doesn't that mean that your not getting the diffusion you should?


It means it's not 100%, sure. But so are ceramic diffusers or any type of diffuser that renders bubbles or a mist. This small Aquaclear filter has been great for up to 3 bubbles per second, near reactor level efficiency. Certainly better than ceramic. Larger models Im sure could handle more.

The point of this thread, which is fairly old btw, was to illustrate the difference between having an * open line* pointing straight up, and having it positioned horizontally. Just a small change I thought was interesting. 

Im still running diy on the same tank using the same Aquaclear filter. But Ive since started using a small piece of chopstick in the end of the co2 line, as sort of a pre-diffuser. That way the filter is working against lots of tiny bubbles instead of one big one, or a few big ones. For all practical purposes it's 100%, with just the occasional small bubble or two coming out, which could just as easily be bubbles of air.



dru said:


> How has the impeller held up over time?
> 
> Great tank BTW!


So far it seems totally unaffected, going on 8 months or so.


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## jrill (Nov 20, 2013)

I gotcha. Then cool beans.


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## dru (Mar 9, 2013)

Sorry to bump an old thread


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## burr740 (Feb 19, 2014)

dru said:


> Sorry to bump an old thread


No worries, mate. It was a valid question, one that could only be answered after considerable time had passed. 

I actually just now edited the title to make it more search friendly


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## quiquik (Dec 13, 2013)

May I ask what your lighting and substrate are? Thanks. I was also contemplating diy co2 and had envisioned putting the hose into the intake tube through the side, that's what caught my attention when I saw this post. Also too what do you mean by chopstick?


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## burr740 (Feb 19, 2014)

Substrate is 100% Black Diamond blasting sand ($7.99 for 50lbs at Tractor Supply) heavily supplemented with Osmocote Plus.

Lighting is two 18 watt spiral CFL bulbs, 5000K, in aluminum dome type clamp-on reflectors. I ran 23 watt bulbs for a while but they were a little too much.

Chopstick means exactly that, a 3/4" long piece of bamboo chopstick, available at any Asian restaurant or grocery store. They make a decent diffuser all by themselves. In this case, what you have is already partially diffused co2 going into the filter rather than one big bubble. It really makes a big difference.

Look close and you can see the chopstick piece. Tank has turned into basically a grow-out/experimental tank. Pic is a couple months old, this is the 3rd HC carpet growing here, I sell most of it off when it gets thick like in the previous pics











CO2 is two 1.89 liter juicy juice bottles + a gas separator/bubble counter bottle. I change out one bottle per week, it stays around 2.5 bubbles per second.











Oddly enough, I put this whole set-up together for about $100. Tank was $20 from Petco dollar per gallon sale, then a $35 filter, another $30 on lights, $8 plus tax for substrate, and say 10 bucks worth of DIY CO2 components.


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## quiquik (Dec 13, 2013)

burr740 said:


> Substrate is 100% Black Diamond blasting sand ($7.99 for 50lbs at Tractor Supply) heavily supplemented with Osmocote Plus.
> 
> Lighting is 18 watt spiral CFL bulbs, 5000K, in aluminum dome type clamp-on reflectors. I ran 23 watt bulbs for a while but they were a little too much.
> 
> ...


Thank you for the info. Got my brain spinning again... just read your 75 gal journal and diy co2 posts. I have a 50 gal that I am considering redoing for the 4th time sooo love seeing methods that succeed.


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## kman (Dec 11, 2013)

That's a great little setup you have there.


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## burr740 (Feb 19, 2014)

Thanks. Ive really learned a lot by keeping this tank.


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## MaiDoM (Jan 23, 2014)

Just wondering, since you added the chopstick to pre-diffuse the co2 and now have smaller bubbles, wouldn't it be more efficient to place it back at the bottom of the filter intake? That way the co2 has to travel a longer distance before hitting the impeller, providing a more efficient diffusion?


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## burr740 (Feb 19, 2014)

MaiDoM said:


> Just wondering, since you added the chopstick to pre-diffuse the co2 and now have smaller bubbles, wouldn't it be more efficient to place it back at the bottom of the filter intake? That way the co2 has to travel a longer distance before hitting the impeller, providing a more efficient diffusion?


In theory, yes it would seem that way. In reality though, it doesnt make any difference from my own experiments. Some of us were brainstorming in another thread (linked now in my sig) how to best use AQ HOBs. I took some PH readings from different positions. To save reposting all the what ifs and various pictures, the results are on the last page.

Edit: Gonna go ahead link the thread in case I ever take it out of my sig this post will still make sense 

http://www.plantedtank.net/forums/showthread.php?t=821665


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## quiquik (Dec 13, 2013)

MaiDoM said:


> Just wondering, since you added the chopstick to pre-diffuse the co2 and now have smaller bubbles, wouldn't it be more efficient to place it back at the bottom of the filter intake? That way the co2 has to travel a longer distance before hitting the impeller, providing a more efficient diffusion?


Just started my new set up with pressurized co2 and put the lines in the hole in the plate of both of my 70 AC's like what burr740 and others and myself were brainstorming in the other thread and it is working flawlessly. I have made another hole with drill in the plates so if for some reason power is lost and comes back on the pumps will start back up with no problem now. Bur740 mentioned this might have been a problem with the one hole being used for co2 line and it did when I started up my new set up so therefore I did drill an extra hole in each plate. No problems now and I have my 1.0 ph drop in about 1.5 hrs and steady from there on out till co2 is shut off with timer. Very pleased


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## MaiDoM (Jan 23, 2014)

Alright thanks for the input! I might give it a try next time I replace my yeast/sugar.

Have you done something to reduce the waterfall/splash effect of the filter that could offgas the co2? At the moment im topping the tank everyday to keep the water level high enough for the filter, and it's a bit of a pain to do so


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## quiquik (Dec 13, 2013)

MaiDoM said:


> Alright thanks for the input! I might give it a try next time I replace my yeast/sugar.
> 
> Have you done something to reduce the waterfall/splash effect of the filter that could offgas the co2? At the moment im topping the tank everyday to keep the water level high enough for the filter, and it's a bit of a pain to do so


during the winter about 1 gal a day or so, as summer approaches it won't be much if any here in nw Indiana. It is what it is, not any different for me than wc's or ferts, feeding, or anything else that goes with the passion of keeping fishy's


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## burr740 (Feb 19, 2014)

I usually top mine up once, mid week between water changes. I like there to be a strong rolling of the surface coming off the filter. Just shy of an actual splash that breaks the surface.


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## mickmac (Dec 29, 2020)

Sorry to bump up this old — but very excellent! — post. But can you tell me the best/safest way to drill into the side of the intake pipe so I can insert the CO2 tube? Don’t want to crack the plastic!


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## NotThePainter (Dec 17, 2020)

mickmac said:


> Sorry to bump up this old — but very excellent! — post. But can you tell me the best/safest way to drill into the side of the intake pipe so I can insert the CO2 tube? Don’t want to crack the plastic!


I've done this before, a bazillion years ago, and I think I just used a hand held drill and got lucky. I was drilling in the thin wall Fluval pipe, which seem thinner than the Aquaclear hang on tubes. 

Build a drilling jig, a 90 degree corner held up at 45 degree angles. This will hold your pipe. Clamp it in that. Now, if you have a drill press, just start with a small bit and drill a pilot hole. Then start going bigger.

Without a drill press. Well, you'll really want to clamp your pipe well and keep a steady hand.

Or.... Slice the intake tube and insert a length of flexible tubing, making it longer. The flexible tubing is pretty easy to drill into and if you mess it up, discard it and try again.


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## EmotionalFescue (Jun 24, 2020)

mickmac said:


> Sorry to bump up this old — but very excellent! — post. But can you tell me the best/safest way to drill into the side of the intake pipe so I can insert the CO2 tube? Don’t want to crack the plastic!


i like putting a piece of gaffer's tape over the pipe before drilling. keeps the bit from slipping and comes off clean. as an alternative, duct tape might help with the slippage, but will leave some funk.


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## mickmac (Dec 29, 2020)

Thanks to you both, @NotThePainter and @EmotionalFescue (love that moniker!). Sounds like me and my paltry toolbox may not be adequately prepared for this job!


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## NotThePainter (Dec 17, 2020)

You're welcome and yes, the tape trick will really help. It is intimidating, but go for it!


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## mickmac (Dec 29, 2020)

Thanks @NotThePainter! I’m intimidated but not afraid. I will be giving it a go ASAP!


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## NotThePainter (Dec 17, 2020)

I really over thought it when talking about building a jig to drill holes in rigid plastic tubing. I'm always doing that.

Here's a guy doing it with a dremel and the pipe held in his hand. Easy!


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## mickmac (Dec 29, 2020)

Well thanks @NotThePainter! I have a dremel and the fitting he’s using to drill the pipe in that video, so I’ll be able to do that I hope! 

My remaining question is perhaps not one you can answer, but here it is: I understand about putting a piece of chopstick in the end of the CO2 line, but can’t picture how it works. Does the chopstick piece need to be sized so it allows some room between it and the interior line so that CO2 flows around the chopstick (in effect the chopstick slowing the CO2 down but not blocking it)? Or is the chipstick bit supposed to fully block the CO2 line, forcing the CO2 to somehow travel through the chopstick?!?


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## quiquik (Dec 13, 2013)

mickmac said:


> Well thanks @NotThePainter! I have a dremel and the fitting he’s using to drill the pipe in that video, so I’ll be able to do that I hope!
> 
> My remaining question is perhaps not one you can answer, but here it is: I understand about putting a piece of chopstick in the end of the CO2 line, but can’t picture how it works. Does the chopstick piece need to be sized so it allows some room between it and the interior line so that CO2 flows around the chopstick (in effect the chopstick slowing the CO2 down but not blocking it)? Or is the chipstick bit supposed to fully block the CO2 line, forcing the CO2 to somehow travel through the chopstick?!?


The CO2 does flow through the chopstick just like a diffuser.


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## mickmac (Dec 29, 2020)

Good to know — thanks! Do you need to make a hole slightly bigger than the tubing to accommodate the square chopstick piece?


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## quiquik (Dec 13, 2013)

mickmac said:


> Good to know — thanks! Do you need to make a hole slightly bigger than the tubing to accommodate the square chopstick piece?


I would use the small end of the chopstick that is round and cut the very end off about 1/4 inch then cut again to make the total piece about a inch long. The larger end into the tubing and the smaller end into the intake tube. Or you can try not using a chopstick altogether and just stick the co2 tubing into the intake tube and see if the propeller will be enough to "diffuse" the co2


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