Fish gasping

[A.Rashid]

Lately, my fishes are mostly at the water surface gasping for air and this only happen at nite,is bcos lack of O² or too much CO²? should I shut the CO² at nite or should I juz pump air to the tank? anyway my tank is 3x2x2 with CO² at 1bpm.

[A.Rashid]

sorry rephrasing my sentence. should be: My fishes will be found on the water surface, gasping for air, in the morning.

[PeterGwee]

CO2 running 24/7 or just when lights are "on"? If you are running CO2 24/7, there might be a possibility of CO2 overdose...it all depends...do a test to find out.

If your CO2 is just "on" when lights are "on", the likely issue is lack of O2 produced by the plants to last the critters throughout the night. Look at your plants...are they growing well? Is your bioload too high for your tank size?

[geoffrey]

I will go along with Pete on making sure your plants are doing well. I have a second smaller tank, 2ft, that runs 24/7 CO2, DIY. No such problems when the yeast/sugar is new, running at 2~3bps using a reactor.

Your plants may not be producing enough O2 to last the night. One good way to check is to see if your plants are pearling on the under side of their leaves. Your bioload also affects the consumption of O2 and your filter/substrate loaded with bacteria will also consume lot of O2 when they decompose wastes.

[juggler]

I guess there's too excess CO2 in the tank. The fish gasping for air in the morning means you are pumping in too much Co2 that can be used up by plants in the lights on period.

Try to reduce the CO2 rate to something like 1 bubble in 3 or 4 seconds.

Other considerations:

Is your lighting level/duration adequate to help the plants photosynthesise efficiently?
Is the tank adequately planted?
Is there too much bioload in comparison to plants?

[vinz]

Ehh... he asked if he should turn off his CO2 at night, so I take that to mean it's 24/7.

Rashid, first we got to take care of your fishes. The cheap automatic solution is to get another timer and connect a small airpump to it. This airpump should be on when the lights go off, and off when the lights turn on. This will lower the CO2 levels in your tank and make sure there is enough O2 all through the night.

The expensive solution is to get a solenoid.

Now, as Geoff and Peter were saying, if you have sufficient plants and they have enough lights, CO2 and fertilisers to photosynthesis well, then your tank should be loaded with enough O2 to last the night by the time the lights go off. This is also dependant on how many fishes/shrimps you have in there.

If your plants are not photosynthesising well, then it could be one or both of the following:
- Simply not enough O2 produced during lights on, to last the night.
- CO2 build up (because the plants are not taking it up), causing CO2 poisoning.

If its because of the plants, then fix that and you can remove the air pump.

[theodore]

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On 8/26/2003 7:55:18 AM

Lately, my fishes are mostly at the water surface gasping for air and this only happen at nite,is bcos lack of O² or too much CO²? should I shut the CO² at nite or should I juz pump air to the tank? anyway my tank is 3x2x2 with CO² at 1bpm.
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Do you have any pH and KH measurements for your tank? If I'm reading your posting correctly :

- CO2 is at 1 bubble per min (that's what bpm means rite?)
- tank size = 3ft x 2ft x 2ft

Even if the CO2 is being injected at 1 bubble per sec for 24hrs everyday, the amount is still too low to result in CO2 poisoning for a tank that size.

[Allen_1971]

Its important to take note of when the event occurs and also if your CO2 is on 24/7. On the assumption that it is, then I agree with vinz's take. A simple air pump on a timer should solve your problem.

As a minor refinement, you may not want to turn on your pump immediately after the CO2 is cut. This is because your tank should be quite O2 rich immediately after the lights go out (assuming your plants are growing well). In which case, switching on your air pump 1-2 hours later will ensure that all the hard earned CO2 doesn't just get outgassed to the atmosphere immediately.

[A.Rashid]

theodore, I tot so too... but in any case when I pump in air to the tank the fish got well, swiming freely. during the day it's fine.. I guess photosysthesis is doing it's job generating O² but at nite... problem arises the next morning....lucky there was no casualty... I hate to see my fish died bcos of my stupidness. I think I will try Vinz method and see how....

will let you all know the outcome...
Thanx alot for the advises....

[geoffrey]

This happened only recently? Did you do anything before this happened?

[eric_kclee]

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On 8/26/2003 2:41:55 PM

theodore, I tot so too... but in any case when I pump in air to the tank the fish got well, swiming freely. during the day it's fine.. I guess photosysthesis is doing it's job generating O² but at nite... problem arises the next morning....lucky there was no casualty... I hate to see my fish died bcos of my stupidness. I think I will try Vinz method and see how....

will let you all know the outcome...
Thanx alot for the advises....
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Becareful with air pump, observed for algae and BBA. Dennerle guide book do suggest that algae do thrieve in oxidising environment and plant doesn't. I had same experimented air pump like you and what the guide book say is very true.

Use it in a control manner(not 24hr) and stop using it after a week or two. Your tank only need temporary assist.

[bclee]

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On 8/26/2003 3:17:44 PM


Becareful with air pump, observed for algae and BBA. Dennerle guide book do suggest that algae do thrieve in oxidising environment and plant doesn't. I had same experimented air pump like you and what the guide book say is very true.

Use it in a control manner(not 24hr) and stop using it after a week or two. Your tank only need temporary assist.
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Oxidising environment... what does that means? I really do not buy into that. In most planted tank, the water is oversaturated with O2 from all the photosynthesis. Is that considered oxidising environment?

Using an airpump will drive out CO2 (& O2 too if the water is already oversaturated with O2). I think the BBA is likely to be due to lack of CO2 rather than "oxidising environment".

BC

[eric_kclee]

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On 8/26/2003 3:41:13 PM
Oxidising environment... what does that means? I really do not buy into that. In most planted tank, the water is oversaturated with O2 from all the photosynthesis. Is that considered oxidising environment?

Using an airpump will drive out CO2 (& O2 too if the water is already oversaturated with O2). I think the BBA is likely to be due to lack of CO2 rather than "oxidising environment".

BC
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Well, I don't have to convince anyone....Just a piece of info/knowledge that I pluck directly from DENNERLE KNOW-HOW guide book on 'ALGAE PROBLEM? We solved them long ago:'.

Not invented myself, tried it and convinced by the result, I used the air pump 24/7.

Also, fully agreed that algae can be caused by other factor too, no doubt about that.

[bclee]

Quite a number of us do not agree with the Dennerle publications. This is one of them.

It is simply because planted tank is full of O2.

If you are using air pump, you are driving out O2 rather than introducing O2. At the same time, you are driving out CO2.

It is well known that lack of CO2 is the cause of many algae problem, especially BBA.

BC

[PeterGwee]

I don't buy the oxidising environment idea like BC...Planted tanks are usually very high in O2 content that no number of pumps running could hit the range. Low CO2 and ammonia are major causes of algae infestation...not high O2.

[vinz]

First, in a tank full of plants that are photosynthesising well (which is what we are striving for), the water is saturated with O2, but these tanks seldom have algae problems. Think about that.

More recently (that Dennerle one has been around many years), there was a discussion about high levels of O2 causing algae to self-destruct. I don't have time to dig up the links at the moment, but you can go search around in the APD and AQ (one or a few threads that referred to the APD discussion). Some of the other AQers who were active in that discussion might be able to dig up the links sooner then me.

Second, using an airpump, at the very most, you can raise and maintain the O2 levels to ambient levels, and that level is much lower then saturation. In fact, if the water was saturated with O2, aerating the water will LOWER the O2 levels until it reaches ambient levels. (Ambient levels are sufficient for fish to breathe normally). So even if Dennerle's theory is correct, aerating the tank will infact reduce the "oxidising environment".

Third, this theory of Dennerle's has been debunk by many experienced hobbyists.

[bclee]

In fact, algae do suffer more under high O2 environment due to photorespiration.

Aquatic plants often use C4 biochemical pathway of photosynthesis instead of C3. C4 provides a possible pathway for recycling CO2 from cell respiration. Therefore, plants can cope with photorespiration better. This contradicts what Dennerle suggest about algae do thrieve in oxidising environment and plant doesn't.

BC

[eric_kclee]

Well, thanks for all the explanation, learning something new today.

Then I should consider re-use my air pump again....because...the last time I use, I throttle it very low (like 1bps, to prevent affecting the PH) through air stone. I use it because my tank was accidentally off-balance by over-trimming.

Then I realise that all the surface slim or protein layer was gone in one day. I like this effect and may want to use it again. Any advice?

I stop using air pump because algae also start to form. After reading all your advice, it may not be related to air pump , may be related to 'off-balance' tank.

[vinz]

Eric,

Your air-pump was on all day? If you aerate the water, you will bring levels of gases dissolved in the water to ambient levels... including CO2. So if you aerated the water of a high-light/growth tank, you will not have enough CO2.

That's why the air-pump is only used during lights-off hours.

[bclee]

Errr... it is still related to the airpump.

Just that it is not the airpump introducing O2 which is causing the algae. It is the airpump removing CO2 that resulted in algae.

If you want, turn it on only during lights off. You do not want to drive away CO2 when the plants are photosynthesising.

But take not like what Allen and some others had mentioned... using the airpump actually reduces the O2 level from the oversaturated level down to ambient level when the lights just go off. If you really want to maximise the O2 level, turn on the airpump only about 2 hours after lights go off.

BC