Near disaster with CO2

What a nightmare I've just had.
Did a big WC on my planted tank tonight, cleaned both filters, big gravel vac, 100+ litres of RO water and I have to say it was past due on this tank.
I put it all back together and got stuck into boob whisperer on the sky plus.

I happened to glance over at the tank about 20 minutes later to see two of my biggest Severums huddled up in the top corner of the tank.
WTF are they at? I wondered, then the rest of the horror show focused in.
All the fish were floating around the tank, some barely swimming, some obviously dead.
Panic set in big time and I was in a state, luckily the wife calmed me down and started throwing options at me.
Thank God for her, (love you babe), I had a 120l tank empty of fish but half full of ph 8.0 water.
It was panic stations so I filled it up with some 7.0 I had heating and the mass netting of fish began.
Fish were so docile they were caught by hand in some cases.
Threw them into the hospital tank with no time for testing water or anything, sure half of them looked dead.

Amazing things, fish.
All bar one baby Angel are now swimming freely and looking fairly normal, though I have no idea what kind of permanent damage was done by.....the CO2 system, I must have hit the knob on the control valve when I was putting the cylinder back into the cabinet. Bloody thing was bubbling like an airstone.

I'm guessing a massive ph crash due to the CO2, anyone got any experience with this?
How do I cure it? What I do know is I'm knackered and 30+ fish ain't gonna live in a 120l tank for long.
That's if I haven't done terminal damage by throwing them into what must be ph 7.6 at least, but it was an emergency.

Lucky alright, you didnt have a Ph crash you just added to much CO2.

Run an airstone in the tank with the CO2 switched off for a couple of hours to try and drive it off and then reintroduce the fish or you could just do another 50% water change, don't know about long term health effects on the fish they should be ok I would imagine.

Hope it ends well for you and not a late night looking after your fish!!

Hi Didihno
Hows everything now after your CO2 incident....???

Lar

Well all my fish survived so far.
I did a big WC again and have a test fish in the tank the past 2 hours with no ill effects so far.
I think it might be safe to reintroduce the stock.

All fish back in tank, looking alright so far.
Only one loss, a stunning little Firemouth.

The thing to remember is to get the waterm oving fast!!!!!! this will drive of the Co2 quicker than anything. power heads full blast and anything else to rapidly give surface agitation,

Been following this thread closely because im setting up a new tank with Co2 very soon.

Justing wonder how do you know if you have enough/too much Co2, what do i use in my drop checker../

And with the reg how do i set that up right..?

Sorry im not tryin to hijack the thread.

Alan

You have to get 4dkh solution and a bottle of API low range ph solution (for colour).

Best advice is invest in a Ph monitor/controller!!!!! cost about 100 euro, may sound expensive but what do you value your fish at?????