# Contemplating CO2



## ourmanflint (16 Nov 2016)

Hi

After 18 months of non co2 in my two cubes, I am considering adding CO2 to the 40cm cube. I have been running them as softwater tanks with a KH of 0.5 (approx. 10ppm KH Test ) and a pH of 6-6.5.

What parameters would I need to move to, to provide a more stable environment? A bit worried that tank would be unstable to pH crashes etc

Also what size cylinder ran at absolute minimum CO2 would I need to get so I can only do refills 1-2 times per year, or is that not possible?


Thanks


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## ian_m (16 Nov 2016)

I use about 0.01gr per litre per hour of CO2 with a green/yellow drop checker.

So 60litres on 8 hours a day is about 5gr per day.

Thus 2 litre FE will last 400 days.
420gr sodastream about 80 days.

I would possibly harden the water up a tad to say 4-8KH, to give you more "getting CO2 levels wrong" wiggle room.

Remember decent light and ferts levels will be required to maximise growth with new CO2 levels.


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## Planted Bows (16 Nov 2016)

Hi,

I have a 30l cube and I have a 2kg fire extinguisher. Thay has been running for around 6 months now and still half full. In terms of your water parameters, your ph will drop around 1ph when Co2 is on. To give an example mine is around the 7ph mark and drops to just over 6 which can be really harmful to fish. Just keep an eye on your fish/shrimp to judge that way. Im not to great with gh and kh values.

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## ourmanflint (16 Nov 2016)

Ok, so a 2-3kg cylinder should last me a year if I don't go crazy with the CO2. Good to know. even the sodastream cannister is not bad I suppose, and I could just switch at my local Argos right? Ian, thanks for the kh advice, I will start shifting it upwards over next couple of weeks, eau de thames should do the job, I think it's around 13KH near me.


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## Planted Bows (17 Nov 2016)

I had my FE delivered to my house 

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## tubamanandy (17 Nov 2016)

Planted Bows: Really not sure if your comments are right.

"To give an example mine is around the 7ph mark and drops to just over 6 which can be really harmful to fish"

Surely the PH drops depends alot on what your KH is and how buffered your water is ? Also, from my experience I don't think a PH drop of 1 would matter in the slightest to most fish as long as its a slow drop.

Anyone else agree ?


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## Planted Bows (19 Nov 2016)

No I do not agree! A 1 ph drop xan be fatal to fish and I've learned the hard way. A slow ph drop isn't as fatal but can still be harmful

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## Planted Bows (19 Nov 2016)

All dependant of the ppm value

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## tubamanandy (19 Nov 2016)

I agree that a 1Ph (x10) drop in PH can easily be fatal but only if its fast - most fish that I keep easily cope with a slow drop


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## Planted Bows (19 Nov 2016)

Yes what I meant was a fast drop lol

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## Planted Bows (19 Nov 2016)

I have noticed that shrimp can't handle it as much though 

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## kadoxu (19 Nov 2016)

The PH drop of 1 being fatal, depends on your water's KH and initial PH.

I use this as a reference



 

Check this PFK article for more info
http://www.practicalfishkeeping.co.uk/features/articles/co2-striking-the-balance


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## ourmanflint (20 Nov 2016)

So what kind of diffuser would you recommend for my AquaNano 40 bearing in mind it's an all in one so no exterior filter.

Thanks


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## kadoxu (20 Nov 2016)

It's up to your taste... the only type you can't use is inline diffusers, which are meant to be used with external filters.

You can get a bazooka atomiser, or a glass diffuser (which comes with a ceramic disk).


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## Planted Bows (25 Nov 2016)

I use a pollen glass diffuser 

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## three-fingers (29 Nov 2016)

This has been written about and discussed extensively on these forums and comes up all the time. Most people seriously misunderstand what pH is and how important it is in different contexts.  A pH crash is not necessarily a bad thing, in a *fish-only* system it could indicate something else bad has happened, the actual pH change itself isn't what hams the fish but most fish keepers do not realise this.

In planted tanks with (often even without) added CO2, large pH swings are commonly experienced at night when the lights go out, and this can happen in nature too. Do not worry about pH when adding CO2 to a soft water (low KH) tank to grow plants, the pH value will drop very low, however it is rather meaningless in this context. If you are really worried, you can add some bicarbonate of soda to the water when doing a water change to boost the KH (which would reduce the pH change). I have very soft tap water too, when I add CO2 I basically just ignore the pH of the water, I have never had an issue with low pH.  Low pH being an issue is basically a myth, with regards to planted tanks anyway. Even if it was an issue...it's very easy to solve...

I was concerned about pH swings too many years ago, so added some crushed coral to my substrate when setting up my oldest planted tank, you can add some in a filter bag (oyster shells/chicken grit works equally well apparently). These will slowly dissolve when the water is acidic, gradually releasing buffering KH compounds.

Darrel (member dw1305) has written some very good replies on this such as the following one: Co2 - sufficient produced overnight?  (Follow the links in each post for more details, there's probably a better sticky topic or article on the forums somewhere, I cant find anything atm though). 

This is a great thread on the topic too: https://www.ukaps.org/forum/threads/ph-less-than-6-digital-ph-monitors.18116/#p185647

I would highly recommend the Bazooka Atomiser for inside a tank, this type seems to produce the finest mist.  The glass ones look nicer, but I've never had a glass one that works as well as the Bazooka.


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## dw1305 (29 Nov 2016)

Hi all, 





three-fingers said:


> A pH crash is not necessarily a bad thing, in a *fish-only* system it could indicate something else bad has happened, the actual pH change itself isn't what hams the fish but most fish keepers do not realise this.





three-fingers said:


> In planted tanks with (often even without) added CO2, large pH swings are commonly experienced at night when the lights go out, and this can happen in nature too. Do not worry about pH when adding CO2 to a soft water (low KH) tank to grow plants, the pH value will drop very low, however it is rather meaningless in this context.


That is it. The drop in pH (acidosis) and fish death are both symptoms of whatever has gone wrong with the underlying water chemistry, it isn't that the pH drop has killed the fish.  

"Racoll" in <"this PlanetCatfish thread"> is a <"biologist"> who works with S. American fish. There is a further discussion, and actual figures here: <"pH drop">.

cheers Darrel


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## ourmanflint (29 Nov 2016)

Just bought a set up today. It consists of 3kg cylinder and dual stage Aquario reg with solenoid and pH Controller. I doubt I would use the pH controller to control the solenoid, but I guess it might be worth keeping it just to monitor pH levels for a while until I feel I know what's happening with the system. Ordered a small bazooka as well, so will try to get up and running end of the week.


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## ourmanflint (27 Dec 2016)

Well this has been going for about a month now and I am really pleased, have set bubble at just under 1 bubble per second, which I know is very low by some but results have been great so far. All the plants you can see were struggling before but are now going a bit mad, and my ongoing cyano problem looks to be turning the corner.


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