CO2 Spray Bar

[Hanuman]

Kudos for the putting time and effort into trying something new. I have to say you went full bore with this and whether it works out or not at the end you did it for the sake of passion to the hobby. 👍

So far the only real drawback I see from this is the addition of yet another piece of hardware inside the tank specially at the front which can be an eye sore for some. Other than that it seems effective but one small note, I think one needs to slightly oversize the bar from inception (one way or another, either length or diameter wise) else you end up with a less than desirable PH drop since the geometry is fixed and you have an overflow which would prevent PH dropping further, assuming you have proper surface agitation, of course. One would then need to decrease the efficiency of the bar by adding something to decrease the surface area of waters/co2 to adjust it, just like you did by adding the tape.

 

[22802]

Kudos for the putting time and effort into trying something new. I have to say you went full bore with this and whether it works out or not at the end you did it for the sake of passion to the hobby. 👍

So far the only real drawback I see from this is the addition of yet another piece of hardware inside the tank specially at the front which can be an eye sore for some. Other than that it seems effective but one small note, I think one needs to slightly oversize the bar from inception (one way or another, either length or diameter wise) else you end up with a less than desirable PH drop since the geometry is fixed and you have an overflow which would prevent PH dropping further, assuming you have proper surface agitation, of course. One would then need to decrease the efficiency of the bar by adding something to decrease the surface area of waters/co2 to adjust it, just like you did by adding the tape.

Thank you for your kind words @Hanuman

So far the only real drawback I see from this is the addition of yet another piece of hardware inside the tank specially at the front which can be an eye sore for some

You can hardly see it when the lights are on. In fact only the three suckers to the glass. The tube is virtually invisible, is obvious only at night when lights are off.

I think one needs to slightly oversize the bar from inception (one way or another, either length or diameter wise) else you end up with a less than desirable PH drop since the geometry is fixed and you have an overflow which would prevent PH dropping further, assuming you have proper surface agitation, of course. One would then need to decrease the efficiency of the bar by adding something to decrease the surface area of waters/co2 to adjust it, just like you did by adding the tape.

Actually mine is oversized, it gives a 1.6 pH drop at full capacity.
I am using the below end piece to create a smaller CO2 reservoir in the tube, reducing its power to 1.4 pH drop. By rotating the end piece clockwise I push the CO2 meniscus up and can further reduce power.



I have some excess bubble escape from here every few minutes, this is how I guarantee that the reservoir is always filled to the same level, while minimising CO2 loss. As long as I see some excess CO2 escaping, I don't care about the precise setting of my CO2 regulator as I know that injection from the bar into the water is a constant.

 

[Hanuman]

ou can hardly see it when the lights are on. In fact only the three suckers to the glass. The tube is virtually invisible, is obvious only at night when lights are off.

Well this is arguable and I am pretty sure that on display tanks it would bother some. One way of minimizing the sucker view but also of making the bar more future proof, is by having adjustable height hooks that hold the bar from each side instead of having suckers in the front. This would also be safer as suckers can also sometimes slide/drift when they get older.

I am using the below end piece to create a smaller CO2 reservoir in the tube, reducing its power to 1.4 pH drop. By rotating the end piece clockwise I push the CO2 meniscus up and can further reduce power.



I have some excess bubble escape from here every few minutes, this is how I guarantee that the reservoir is always filled to the same level, while minimising CO2 loss. As long as I see some excess CO2 escaping, I don't care about the precise setting of my CO2 regulator as I know that injection from the bar into the water is a constant.

Yes was actually going to comment on that. Having a rotary end piece enables you to adjust the contact surface since it's a cylinder. 👍
Here is an improvement you can do to make it safer and more reliable. The rotary cap could have clicking notches with some graduation to make it easy to visualize and assure you are always at the setting you want it to be.

 

[22802]

Well this is arguable and I pretty sure than on a display tanks it would bother some. One way of minimizing the sucker view but also of making the bar more future proof, is by having adjustable height hooks that hold the bar from each side instead of having suckers in the front. This would also be safer as suckers can also sometimes slide/drift when they get older.

Agree. BTW, I take the bar out at each maintenance, replace it afterwards. Perhaps in the future we mount it on the back, just under the water spray bar, but here we lose the benefit of the dissolved CO2 going straight down with the water flow to the plants.

Yes was actually going to comment on that. Having a rotary end piece enables you to adjust the contact surface since it's a cylinder. 👍
Here is an improvement you can do to make it safer and more reliable. The rotary cap could have clicking notches with some graduation to make it easy to visualize and assure you are always at the setting you want it to be.

Here they are, you see the black dots? I use these to precisely reproduce my rotation settings 🙂
From the top view you can also see the meniscus of CO2, and that indeed the bar is only about 60%-70% filled.

 

[Hanuman]

Perhaps in the future we mount it on the back, just under the water spray bar, but here we lose the benefit of the dissolved CO2 going straight down with the water flow to the plants.

Not sure it will change anything. In my opinion, having the bar under the spray bar wouldn't be detrimental because the flow momentum would carry automatically the CO2 charged water up to the spraybar and accros the tank again. It's a circular motion so whether in front or at the back I don't think it will change much if anything. Try it and let us know.

 

[22802]

Not sure it will change anything. In my opinion, having the bar under the spray bar wouldn't be detrimental because the flow momentum would carry automatically the CO2 charged water up to the spraybar and accros the tank again. It's a circular motion so whether in front or at the back I don't think it will change much if anything. Try it and let us know.

You are most likely right on this one, although I still have some doubts how much efficiency would be lost due to increased outgassing.

If like you, most people worry about mounting on the front, I may have to give priority testing it on the back. For me personally, and I am one who really likes a clean view, I have very little problem with the front mounting as I really can't see the tube. But my main reason to report here is to serve the hobby, rather than just my own tank.

PS just checking my tank, and see that my spray bar would not fit on the back, it is too long. Would have to make another one, just when I thought I was done making prototypes... 😉

 

[Wookii]

Interesting concept - this harks back to the CO2 diffusion systems that first came out when CO2 started to become commercially available for aquarium use. My first Dennerle CO2 diffuser that I bought some 20-25 years ago was essentially an inverted clear plastic try with a CO2 inlet pipe on the top - the tray was positioned with suckers on the glass just above the filter outlet. The tray would slowly fill with gas, and the water movement underneath it would diffuse that gas into the water column.

They then moved onto the various bubble track type diffusors to increase contact time (though I think they were more popular simply because people like to watch the bubbles travelling up) - amazingly Dennerle appear to still sell them!

 

[22802]

I just built prototype V.5, after some gentle pressure from @Hanuman . As I mount it on the back, it can't be full tank length as I have some limitations with hardscape.

After giving my plants a very hard time while playing with CO2 levels I was just for one week stabilising the tank at a 1.4 pH drop. I hope this shortened V.5 CO2 Spray Bar, positioned in a less optimal position for CO2 absorption will get me to that same level otherwise my plants get still another challenge.

 

[Hanuman]

I just built prototype V.5, after some gentle pressure from @Hanuman .

dammmm you sound like my wife that told me the other day that I forced her not to take her 3rd covid vaccin shot 😂. Despite me being very skectical about this vaccin and having shared that with her, I couldn't believe I was being branded an authoritarian dictator... Since then she realized the madness of her words... well I think she did... I'll check tonight again to make sure 😂

 

[22802]

I am now running a new CO2 Spray Bar, on the back just under the water spray bar. This one is only 80% of tank length, due to limitations with the hardscape.

I tuned it with the end button rotation at pH 1.1 drop, slightly below its maximum capacity.

After coming from 1.4 my plants won't be happy with another pH 0.3 adjustment, which corresponds to about 50% CO2 ppm change. I will now settle for the long term at 1.1 pH drop and will hopefully be forgiven for the inconvenience I caused.

pH 1.1 compared to my old 1.4 is more comfortable for livestock, reduces CO2 consumption and is faster to stabilise.

Below the FTS, it looks indeed a bit cleaner than the mounting on the front.

 

[22802]

My focus over the past weeks has been to optimize long term CO2 stability, day-to-day and week-to-week.

With the CO2 spray bar on the front of the tank (as per my first postings) CO2 stability is really good, both short term and long term. Yet after mounting on the back I experienced a slow long term drift of pH, about 0.1-0.2 over several weeks.

With the CO2 spray bar mounted on the back, below the water spray bar, it is impacted by changes in the water flow -- as plants on the back of the tank grow towards the surface:



The solution with improved performance is to position the CO2 Spray Bar in front and slightly above the water spray bar:



The most relevant parts of the water flow (around CO2 Spray Bar and surface agitation) are now virtually independent of the planting and flow lower in the tank, and I find long term stability within a couple of hundredths on the pH scale.

With only 80 cm of CO2 Spray bar in my 200l tank the pH will drop 1.5, with my current setting of the overflow (see below).

A full tank shot, the CO2 Spray bar is hardly visible (slightly above the water spray bar).



Building the CO2 Spray Bar is now a bit more work, but with the experience of nearly 10 proto types I manage within one hour and just a few GBP materials expenses.



For the finetuning of the pH drop (i.e. size of the CO2 reservoir) I do not longer rotate the end piece (it is now fixed with a screw), but prefer to exchange end pieces that each have a hole drilled in slightly different positions. The picture shows my favourite (1.5 pH drop), with the CO2 meniscus visible in the overflow.



Yesterday I celebrated a milestone, bought a bunch of new plants that will not anymore be mistreated with CO2 experiments. Will farm these plants and try a nice and healthy tank again. I hope that my experiments, and final solution will be helpful for others in the future.

I will not go back to a reactor again, let alone diffusers, the CO2 Spray Bar is simple and is the best solution I have had over the years.

 

[Wookii]

Interesting idea, but what about surface agitation? I always angle my spray bars up so the outflow hits the surface - I'd consider this essential to get enough surface agitation and sufficient surface gas exchange, With the CO2 diffuser placed there it looks like it will kill any potential surface movement?

 

[Hanuman]

Interesting idea, but what about surface agitation? I always angle my spray bars up so the outflow hits the surface - I'd consider this essential to get enough surface agitation and and sufficient surface gas exchange, With the CO2 diffuser placed there it looks like it will kill any potential surface movement?

Look to the right of the tank 😎

 

[22802]

Interesting idea, but what about surface agitation? I always angle my spray bars up so the outflow hits the surface - I'd consider this essential to get enough surface agitation and and sufficient surface gas exchange, With the CO2 diffuser placed there it looks like it will kill any potential surface movement?

You may still direct the spraybar upwards, and just position the CO2 spray bar a little higher as well. I usually direct my water spraybar parallel to the surface, which gives enough agitation.

 

[22802]

Look to the right of the tank 😎

On the right 20 cm I don't have spray bar, as I have wood over there.

 

[Hanuman]

Isn't that a wave maker?

 

[Wookii]

Isn't that a wave maker?
View attachment 191915

Yes, a gyre by the looks of it - I'm guessing that's just for use at night or something, as it would defeat the purpose of the spray bar configuration otherwise.

 

[Aleman]

Hmmm, I'm liking this, and as it so happens I have a piece of 32mm Polycarbonate tubing that I could 'sacrifice' in the interests of science ... Just need some 32mm polycarb or acrylic end caps ...

 

[22802]

Isn't that a wave maker?
View attachment 191915

Yes I bought that one when I used a different set up, with a spray bar on the right. Now, with spraybar on the back I don't really need it anymore, but let it spin for 2 min every hour to give the water a bit of a mix and the fish some fun. I find a flow from the back to the front most friendly to stem plants that don't have to bend from left to right, as well as for the fish.

 

[Aleman]

Hmmm, thinking about this a bit more. Just how do you make 2 straight 90cm cuts in polycarbonate tube without it cracking, splitting or melting? I have a Dremel, with cutting wheel ... would melt and gum up, diamond wheel ... same, Circular saw .... err just no, Recip saw ... not a frickin' chance! Multi-tool ... vibrating with a fine blade on slow speed, and take it slowly ... Possible ???