DIY CO2 Issue

BoneyT

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11 Feb 2020
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uk
Hi All,

I am after a bit of help please. I have an issue where I have clearly done something wrong but I dont know what or how to fix it...

I have a 400L tank and since day 1 adequate co2 output has always been an issue, this week I have attempted to use the DIY method that @foxfish uses. Please see link here -
https://www.ukaps.org/forum/threads/high-flow-diy-reactor-now-with-video.23337/

The problem is, is that my setup is not diffusing the CO2 all the bubbles seem to be making there way back into the outlet pipe and forming in the spray bar as shown in the picture below

IMG_20200505_133648[1].jpg


I am using one of the newer 10" water filter canisters as the old 12" ones are now impossible to find, the clearance at the bottom of the canister is about 4 and a half CM see below

1.png


Heres a couple of poor quality photos showing the canister setup
IMG_20200505_133653.jpg
IMG_20200505_133704.jpg


So heres some technical details

CO2 solenoid switches on 3 hours before lights come on in tank, releasing roughly 8 bps

My Filter is a Betta Choice 2000 UV filter which will turn around 2000L an hour, tank is 400L

At lights on my co2 drop checkers is still green it looks like it hasnt changed (fluid was replaced on Saturday)
so I am doubtfult any CO2 is dissolving in the tank.

I think my problem is one of the following

a) Clearance at the bottom of the canister is too large, majority of bubbles are pushed below this threshold and are escaping

b) The flow isnt strong enough into the canister and this is why the bubbles are not dissolving

c) co2 is coming out of the diffuser with too much force, being pushed straight down and then escaping before having chance to react with the water coming into the filter

But these are all just guesses, I dont know what I am doiung, more imprtantly I dont know what I am doing wrong.

Can anybody please help? please let me know if you would like any more info/pics etc

Thanks!
 

foxfish

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11 Oct 2009
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It seems the bottle shape can make a difference as can the flow rate but as you can see in my video it will work with high and low flow rates.
Is there any way you can adjust the flow, is there an inline valve you can adjust?
I think I only had one inch clearance below the bottle.
The principle is that the flow is quickly diffused as the water enters the bottle and the C02 try’s to float back up and then gets pushed down again and again until it dissolves.
So if it is going out the bottle bottom I would think a wider bottle with a neck that immediately opens out will be the best shape the longer the better, just 22-25 mm off the bottom should be fine.
 

BoneyT

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11 Feb 2020
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Location
uk
Thanks for responding @foxfish so if I am understanding this correctly, you would recommend a bottlle shaped more like this

Splash.png

Than say a sprite bottle?

640x640.jpg
 

BoneyT

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11 Feb 2020
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uk
Spraybar is pointing down - should be pointing horizontal with the water ideally hitting the front glass when you remove 50% water for WC

Hi @Zeus. Usually it is, I adjusted it to this to capture the bubble buildup. Unfortunatelty though the output is no where near powerful enough to hit the front glass, maybe covers 60 - 70% of the distance but thats it
 

ian_m

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Flow needs to be something like this in order to get sufficient CO2 flow around the tank.

 

BoneyT

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11 Feb 2020
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Location
uk
Hi @ian_m unfortunately my tank has never had that level of flow, I have had issues with my filter since day 1, its meant to be silent but makes a racket, something in the head unit is loose and I think it is probably effecting the flow rate,

This is the filter https://www.cmcaquatics.co.uk/betta-choice-2000-uv-external-aquarium-canister-filter-540-litres

You would have thought the above video would be achievable with that filter and a 400L tank but im just not gettting it. All the reviews I have read about the filter seem to be promising so I think mine is probably just faulty. As soon as the lockdown is over I am going back to my LFS to see about getting it looked at.

@foxfish Thanks for your responses, unfortunately I cant get anything with that shape as they are all too wide for the canister but I have found a bottle which is as close as.... sadly its not long enough so i brough 2 and joined them together it more or less works....

So I used this new setup yesterday, still getting bubbles come through unfortunately.. I think they might be coming out at the top rather than the bottom so I will use solvent weld to join the bottle top to the canister and see how that goes. Despite all the bubbles still coming though for the first time yesterday with about 2 hours until lights off, several of the plants started pearling, this is the first time I have ever seen this happen in the tank in the 8 months its been set up so it looks like I am on the right track, thanks again to everyone who has responded/helped with this issue so far.
 

foxfish

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Guernsey
Oh well a bit of progress ... it is a shame those older shape 12’’ canisters are no longer available as mine worked faultlessly for many years.
You might be able to wrap some electric insulation tape around the fitting to get a better fit.
Are you using an atomiser on the C02 or just the bare tube end?
It might be worth experimenting by pulling the tube down to a lower level ... i cant really see how yours is set up?
 

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