Possibly emergency, maybe coincidence?!

[bobd_uk]

OK. I installed a CO2 unit in my (30 UK L) tank yesterday morning. Only running at 30% as I plan to gradually increase it so as to lessen the stress on my fish.

Tested ph, gh, kh and iron last night - no change in any since before it was installed. This morning I have one dead cardinal. All the other fish seem fine.

I think this is just coincidence - anyone else got any thoughts?!

Other fish in the tank:

13 cardinals
5 white widows
1 glowlight
1 x ray tetra
2 ancistrus
(No I haven't finished stocking yet - just moved house)

 

[bobd_uk]

Oh, and I meant to mention that it is an electronic CO2 system, not a gas canister.

 

[Sea_Monster87]

Test the nitrates, they can be killers if too high, and I learned that the hard way.

 

[Cian McLiam]

Are any fish gasping for oxygen? as you add CO2 you push out useful oxygen, but im sure you knew this, if that isnt it, then its possibly coincidence, cardinals are pretty delicate anyway. I wouldnt run the CO2 at night though when CO2 will rise naturally anyway.

Ken

 

[Globel]

Try using an airstone or soemthing at night to release the co2 at night.

 

[becs66]

As far a I understand the levels of CO2 in water have no direct effect on the levels of other dissolved gases in the water but at night when the plants are no longer photosynthesing CO2 levels will increase. This causes a problem for the fish as when CO2 levels in the surrounding water get too high CO2 from their gills can not exchange into the water causing the fish to suffocate.

If you are worried about this one way to prevent this is to run an air pump at night or increase filter output, anything that increases surface aggitation which causes rapid CO2 loss from the water. Another alternative is to turn the CO2 off at night. Using the air pump/running CO2 only in the day however can cause problems with shifts in pH, another thing that upsets the little fishes, but this will depend somewhat on the buffering capacity of your water ie its carbonate hardness(alkalinity). The best thing to do is to monitor your water's pH first thing in the morning before the lights come on, and compare this to when the lights have been on for a good while to make sure there is no great fluctuation.

Hope this info is of use!

 

[bobd_uk]

I think it will be.

Unfortunately I have just had a mass death spate in the tank, and I'm now left with just 8 fish. Nitrite went from absolute zero yesterday to 0.6 today. Have done a 30% water change - remaining fish look better.

For now, CO2 unit is off and airpump is running. Long term, I think I'll go for CO2 in the day and O2 in the night. Does this sound OK to anyone with experience of this?

Thanks again!