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Planted Tanker
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Discussion Starter · #1 · (Edited)
As some of you know, I've been experimenting with DIY CO2 in a 20H these last few months. For diffusion Ive had the raw CO2 line running into the intake of an Aquaclear HOB. The prop chops up the bubbles, which then have to flow up through the media before reaching the outflow.

Due to the Aquaclear's design, it is actually a more efficient version of the popular little Hagen filter mod - https://www.youtube.com/watch?v=liuXWQcJCcU

But I digress...What I discovered is that it makes a huge difference whether the line is running vertically or horizontally. Initially I had the line running straight up through the bottom, like you see here -



There was one big bubble at a time coming out. When it hit the propeller there was a distinct chirp sound. From the outflow came a small amount of very tiny bubbles, larger than mist size, but small enough, and few enough, to indicate that decent diffusion was taking place.

Just to tidy up the look of things, I decided to drill a hole in the intake pipe near the surface, and run the line in there instead of having it come up through the bottom. Like so -




This one change made a huge difference in what kind of bubbles came out of the line.

Instead of one big bubble at a time, there is now a steady stream of small bubbles, too many to count, in rapid succession. The change in position alone became it's own diffuser of sorts. No more chirping sounds. You can still hear it, but it's more like a very faint, steady hiss. Visible from the outflow now is a sparse, extremely fine mist, which I believe indicates a better rate of diffusion.

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

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Planted Tanker
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Discussion Starter · #3 ·
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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Planted Tanker
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Discussion Starter · #5 ·
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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Planted Tanker
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Discussion Starter · #8 ·
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.

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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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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Discussion Starter · #13 · (Edited)
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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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.

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.
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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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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Discussion Starter · #18 ·
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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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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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 :p
 
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