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Hi,
My local supplier reckons that i have to turn my co2 off at nite because he reckons that in the long run the fish wont last as long is this right and he also said that i have to run a air stone at nite to break up the surface because the co2 leaves a covering on the top of the water and the bubbles break up that covering what are your experiences and opinions on this
cheers tim

Not generally a good idea, for one you'll be driving the CO2 out of the water, and for another your tank will go thru a ph swing as you drive the CO2 off.
I would leave everything as it is unless you've seen your fish gasping for air in the mornings.

^_^


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And though it’s red blood bleeding from her now. It's more like cold blue ice in her heart.
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the only time you should be turning off the co2 is either if (a) your fish are gasping at the surface in the morning because they have no oxygen or (b) you have a computer controlled ph meter which will shut off the flow of co2 if a certain target ph is reached. or (c) you are tired of growing plants and don't need it anymore but since that isn't the case (i hope) then you should not have to turn your co2 off at night.

as for a covering on top of the water, that is usually caused by something in the food you give your fish. i get that sometimes in one of my tanks that *doesn't* have co2 on it. if you have this, then you should probably cut back a little on the amount you feed your fish, it isn't caused by co2

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"That's the trouble with political jokes in this country... they get elected!" -- Dave Lippman

Eureka,

What type of CO2 system are you running? Is it a Do-It-Yourself (DIY) set-up or is a pressurized cannister system? What are the water parameters of the tank (pH, Kh)?

Your local supplier gave you interesting advice as plants only take up or use CO2 in the process of photosynthesis. During photosynthesis, plants repire (breathe out) oxygen. This process occurs only during periods of light. At night, plants take up oxygen and respire (breathe out) CO2.

So, at first blush, the advice seems to make sense. Give plants CO2 when they can use it, during the day. Don't give plants CO2 when they don't use it, at night. Additionally, as CO2 rises in solution, pH will decline.

Changes in pH are stressful and in some cases, damaging to fish. A stable pH is perfect for fish. Fluctuations are bad. So...

If you have a well buffered tank with KH of 4dgh or 70 ppm or more. A DIY CO2 system running probably should run all of the time as long as it is not bubbling away like a boiling pot. A couple of bubbles per minute is OK.

If you have a pressurized system, it is a good idea to have a pH sensor that opens and closes your CO2 feed to the aquarium. Better peace of mind.

__________
"To steal ideas from one person is plagiarism; to steal from many is research."
researched from Steven Wright

Hey Bob,
I am setting up a pressurized system that is going to run of my cannister filter and my Kh is 4 with a ph of 6.8 so they are good, im am a bit concerened by what this man told me as i am setting up a discus tank and they cost alot of money, but most people have told me so far not to turn off the co2 and not to run bubblers at nite, bensaf told me not to, but the bloke said that you wont see any problems first up but down the track your fish will not surive for as long

my vet has a big display tank with discus in his waiting room, which he has co2 running pretty much non-stop. he has a computer controlled valve so that it shuts itself off when it reaches a specific target ph, but that is to conserve co2, not for fish preservation. anyway, he has had the same discus for well over a year and no adverse problems that i have seen. and some of his discus are getting to be more than 6 inches across, so they are not having many problems that i can see.

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"That's the trouble with political jokes in this country... they get elected!" -- Dave Lippman

the bloke said that you wont see any problems first up but down the track your fish will not surive for as long

To be honest this sounds like complete hogwash to me ! I would like to know on what basis he came to that conclusion ? Sounds like a man desperate to sell a Solenoid valve to me.

The 2 worries people have about Co2 and fish are:
1) More Co2 = less Oxygen. Nonsense. There is no relationship between the 2 and in fact quite the opposite is true. The water in a Co2 supplemented tank is likely to be more oxygenated then a non co2 tank. Healthy plants produce oxygen, a lot. A common sight in co2 tanks is plants "pearling". What is pearling ? The plants are producing so much oxygen that the water is supersaturated and can not hold any more oxygen so the resultant excess oxygen is seen as bubbles on the plant leaves. You cannot get any more oxygen into your water then that !

2) The plants produce C02 at night therefore the pH will drop or the Co2 content will rise to a level harmful to the fish. Again an old wives tale. Yes both happen but not to any meaningful extent. Think about it, if the plants produced that much co2 at night we wouldn't need co2 injection ! The plants would produce so much at night that there would be enough to sustain them throughout the day. Well we know this is not the case. The resultant pH swing at night are minor , no more so then in a non Co2 tank. The same swing at night will been seen at night in a tank that is Co2 injected or not.

All I can offer is my own experience. I have a large very heavily plant tank, inpenetrable in places. I am overstocked fish wise. I've got fish ranging in size from small 1" pencilfish to a fullgrown adult angel. I pump in a lot of Co2 to maintain at about 20-25ppm. I leave it on 24/7. It has been running this way for about 6months. Never lost a fish in that time. Never seen a fish show discomfort or gasp at the surface. Quite the opposite, early in the morning it's like a roman orgy in there !

As for Discus. I've never kept them but from what I hear they need clean water with low nitrates and a relatively low pH. The single best form of Nitrate control is healthy plants, a co2 injected tank with a good stock of plants is going to struggle to see Nitrates above 5ppm. The only good way to lower and maintain pH level is by Co2 supplementation. So a Co2 tank sounds like Discus heaven to me !

For me it's quite simple. Healthy plants = healthy fish. A fish death is a very rare and shocking event in this tank , illness is almost unknown. I put this down to the plants which keep the water clean and oxygenated, provide a sense of security and a source of food as well as a playground and a home.


Last edited by bensaf at 02-Mar-2005 20:56

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Some days you're the pigeon and some days you're the statue.

Remember that age and treachery will always triumph over youth and ability.

Hey Bensaf,
Once again thanks for the post, how often should i check my ph and kh once i have co2 going.
i tried my co2 set up last nite and there were heaps of bubbles circulating up and down and around in the diffuser then reasling into small ones out of the bottom is this right? and i had 1 bubble per sec, could i increase that to two bubbles per sec in the first couple of weeks to get my co2 level up
thanks tim

Eureka,

Sounds like your diffuser is doing what it should be doing You want them swirling and bouncing around so as they break up to smaller bubbles and dissolve into the water.

Start at about 1 bubble a second and then gradually increase each day until you hit the desired level of Co2.It's important for the fish that the Ph doesn't fall too far too fast.

While you are setting the Co2 you'll want to check your KH and pH daily (or even twice a day)until you have reached your desired level and are sure it's stable.The best time to check is early in the morning before lights on, this will be when your pH is at it's lowest. As the plants use up the Co2 during the day the pH will rise slightly and will be at it's highest just before lights out. Just bear this in mind.

After that you only need to check once in a while. I actually use one of those Co2 indicators that you put in the tank on the glass. They are pretty crappy as they really only give you a high, low , normal reading, but I find them handy as a quick refernce that everything is ticking along rather then check the KH/pH every 5 minutes.

After that keep an eye on Nitrate levels. The co2 should kick the plants up a gear and they will use up the nutrients faster. Don't let the nitrates drop to zero or even below 5ppm.It's a good idea to measure Nitrate now and then every few days(or before your water change) this will give you an idea of how much nitrate your tank can "consume". Once you know that it's quite easy to keep on top of things without frequent testing.

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Some days you're the pigeon and some days you're the statue.

Remember that age and treachery will always triumph over youth and ability.