Fishes swimming to surface after intro CO2

**Biofeedback** · 1st Aug 2009, 09:56

Hi guys, I've just started injecting CO2 2 days ago, I realize that my smaller fishes are swimming to the surface this morning. Is it because there's not enough O2 in the tank?

Mine is a heavily planted 1ft tank with a glass cover, i use a fountain filter that constantly circulate the water surface. I don't turn on my CO2 at night.

RIght now I have removed my cover, thinking that it might have trapped the CO2.

Any other opinions?

**gentle** · 1st Aug 2009, 10:24

i think you introduced too much CO2

the fishes are gasping for air...

better stop the CO2 and introduce air pump to aerate the water before they die of CO2 poisoning...

**Jimmy** · 1st Aug 2009, 10:27

reduce the CO2 input level bit by bit till all of them happy again. CO2 is good for plants! the more the better! hehe...

**Biofeedback** · 1st Aug 2009, 10:40

Thanks guys.

But I've only been using 1.5 bubbles, the most 2 per sec.... and I do switch it off at night. Isn't the photosynthesis of the plants suppose to help?

**rav** · 1st Aug 2009, 18:25

Seems like you're pumping in too much CO2. Remember it's always a juggle between CO2, Fert and Lighting. Any deficient in 1 item will slow down plant's photosynthesis. Usually we'll go slow on the CO2 and increase it until the optimum is reached. 1.5/2sec for a 1ft tank might be an overkill. 3ft tanks usually will go to a max of 1/1sec.

**pustefix8965** · 1st Aug 2009, 20:13

During the night, plant will stop photosynthesis and will produce CO2 during respiration. That's why CO2 will accumulate and might be high in the morning. In my low tech tank without CO2 injection if I have not enough surface agitation, sometimes my fish will grasp for air in the morning.

**Biofeedback** · 2nd Aug 2009, 21:54

Good News!! After doing a 30% water change and shutting off my CO2, and running my lights for the whole day, the fishes are not swimming to the top all the time.

Now I just have to fight off the temptation and leave my CO2 off for one more day

**|squee|** · 4th Aug 2009, 11:23

Adjust your filter output to create some water surface agitation. Although this results in some loss of CO2 while you're injecting it in the day, it saves your fishes.

**Biofeedback** · 4th Aug 2009, 23:42

The fishes seems to be doing better. I have reduced the CO2 to about 1 bubble per 10 to 15 secs, introduced a fan and adjusted the filter to agitate the surface.

**Jimmy** · 5th Aug 2009, 08:54

Originally Posted by Biofeedback

The fishes seems to be doing better. I have reduced the CO2 to about 1 bubble per 10 to 15 secs, introduced a fan and adjusted the filter to agitate the surface.

1 bubble per 10 to 15 sec? wow... how's the plant then

**|squee|** · 6th Aug 2009, 19:17

1 bubble per 10 to 15 secs, with the fan and agitated surface... the CO2 you're injecting is negligible. Increase the CO2 bubble count bit by bit day by day, until your fishes start to gasp at night. Once that happens, reduce down the bubble count to the last safe level.

That's your maximum CO2 input. Now all there's left is how well you mix your water and CO2.

**Biofeedback** · 7th Aug 2009, 10:14

Originally Posted by |squee|

1 bubble per 10 to 15 secs, with the fan and agitated surface... the CO2 you're injecting is negligible. Increase the CO2 bubble count bit by bit day by day, until your fishes start to gasp at night. Once that happens, reduce down the bubble count to the last safe level.

That's your maximum CO2 input. Now all there's left is how well you mix your water and CO2.

Mine is a 36cm tank. So would too much bps be too much? I've increased the bubble count to 6 per sec this week. ONly 3 or 4 or my glow eyes would be gasping on the surface at night, they've stopped doing that in the day.

My plants are growing pretty well for now. Will try finding the Max CO2 input like you suggested.

Thanks for all your advice

**|squee|** · 7th Aug 2009, 10:40

I see, then the bps should be fine if your plants are growing well and there's no algae!

**Foxtrotperv** · 14th Sep 2009, 15:59

I'm having the tank size like yours but without the cover.

Try 1 bubble 2 sec and use a photoperiod of 6 hours.
Put the remaining 18 hours on air pump.
Thankt ought to settle the isse.
Another thing that might cause them gasping for air is the fact that the water might be dirty due to ammonia spike.
How often do you do water change?

**Biofeedback** · 15th Sep 2009, 15:30

Thanks for all your advices.

I have tried a few things and played around with a few scenerios.

1) The fishes have seemed to gotten use to the CO2 after a while.

2) After that, I had to increase the CO2 capacity and decrease light hours because I started having algae. Some fishes went up gasping again, not as many as the first round though.

3) I've changed the position of my diffuser, i think that has somehow improved the CO2 concentration in the water without affecting the fishes. I'm basing this on the increased amount of pearling and no fish swimming to the surface. At the same time, I'm also doing more frequent water change, so that might have helped.