# CO2 Overdose???



## pdoutaz (May 13, 2010)

Checked my 120G this AM - have 2 fatalities and another dozen or so fish hanging aroud the surface - seem to be trying to get air. The other fish also seem to be gilling quickly - is this too much CO2??

Just replaced an XP4 and 2 AC110's with a new FX5 - transferred some media from old to new when I swappped out - could this be an issue?

Currently doing a 50% water change and have shut CO2 off completely

ALL comments / feedback greatly appreciated


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## neven (May 15, 2010)

Most likely its a lack of oxygen. How are the temps there? i know yesterday got pretty warm in the afternoon and caught my place off guard (no AC on), so it could be that. another thing is how is the surface agitation, Since you a co2 tank, its more worth it to have a little bit of co2 degassing for the agitation.

Also do you have a drop checker? if not get one. They are handy little things that give a great visual indicator on co2 levels, keep in mind theres an hour to two hour delay when fine tuning it.

One last thing, i always keep an air pump on hand, so if i notice the fish are looking starved from oxygen, i throw the air stones in under the filter outtake, and plug it in. Normally in no time i got happy fish again.


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## pdoutaz (May 13, 2010)

I agree it's probably lack of O2, but I'm confused, I thought a bubbler was a no-no whern running CO2 (surface agaitation)??


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## davej (Apr 28, 2010)

There's a good chance you had an overdose of CO2 from the sounds of it. If you have a solenoid on your CO2 system it is a good idea to have a timer on it to shut it when the lights go out. As there is no photosynthesis going on there is no need for the extra CO2. In fact the plants to a small degree use a little O2 and give off small amounts of CO2 in the dark.


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## neven (May 15, 2010)

I wasn't saying run it all the time, i just said its a great emergency measure when the fish are suffering, as it'll drive oxygen into the water column at the expense of your co2. As for the agitation, gettin the surface to the point where its moving fast but the surface isn't breaking is where you want to be


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## pdoutaz (May 13, 2010)

Thanks Neven and davej,
CO2 is on a timer, goes on/off same time as lights. 2 more questions for anyone - I have a drop checker, but it ALWAYS shows a higher PH then when I use my (new) PH test kit - why is that?
Secondly, do I need to have a bubbler running now that I've removed the AC110's, I was told with CO2 I do not want any surface agitation, but as the fish all look MUCH better after completing a 50% water change, I'm not sure if problem was lack of oxygen or CO2 overdose (maybe both)?


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## CRS Fan (Apr 21, 2010)

I would say it could well be a mini cycle. I suspect that the change in filtration did it causing a spike in ammonia. I have had this happen with my high tech tanks when I overwash sponges, convert filtration types (using cycled media), and adding additional substrate. I usually see my fish gasping. 

It could also be a CO2 overdose or a lack of oxygen. Do you have a drop checker? Many planted tank enthusiasts will run an airstone overnight when the CO2 is shut off because in highly planted tanks, the plants compete with the fish for O2 at night.

You could also angle the FX5 spraybar up at a 45 degree angle to the surface so a rolling boil effect is noticed at the surface. I do this with my Fluval 205 and I have stopped using an airstone at night. I use an atomizer as a diffuser an it is extremely effective at disolving CO2 in the water column. 

Hopefully this helps. 

Best Regards,

Stuart


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## pdoutaz (May 13, 2010)

Neven, you posted while I was typing the previous - the FX5 does seem to get the water moving quickly, so if I'm reading your replies correctly - I had my CO2 too high???


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## 2wheelsx2 (Apr 21, 2010)

If the drop checker shows yellow while your CO2 cycle is on, then you have it too high. One thing that's missing from this thread is, what is your fish load compared to your plant load? Ideally, you want to show your CO2 off before your lights go off too, and start it a bit before your lights come on. That would help keep you CO2 at 30 ppm during the photo period and dissipate it after the period.

Perhaps a picture of your tank as it is now would help. One thing I do with my filter outlets is to point the outlets parallel the surface or even angled up slightly to help the surface turnover without breaking it. This would promote gas exchange without excessive CO2 offgassing. And I also agree with Stuart that it may be a mini-cycle. Have you measured your ammonia and nitrites? Ideally, you would have put ALL of your biomedia from the other filters into your FX5, but since your tank is planted, it shouldn't have been a problem, but it depends a bit on how densely planted it is, and what kind of plants are in there.


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## pdoutaz (May 13, 2010)

Heavy fish load, but also heavily planted
Current parameters after water change:
GH: 120
KH: 40
PH: 6.4-6.6
Nitrate: 50+ (VERY hard to tell with this test kit)


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## 2wheelsx2 (Apr 21, 2010)

Are you dosing EI? The nitrates seem very high for a CO2 injected tank. Especially after a 50% WC.


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## EDGE (Aug 24, 2010)

nitrate test kit can be very inaccurate if you feed a lot in the tank. I stopped testing altogether when I was feeding beefheart in the planted tank The nitrate test kit would registered the highest concentration and yet the plants would still show signs of N deficiency. Most plants cannot use organic nitrogen and a few nitrate test kits I have come across picked up the organic N and factor that in the ppm level. Same goes for phosphate test kit. Back in the days, I used to do 80-90% water change with no fish loss. 


Do you have any surface agitation? You can do more harm with no surface agitation than good trying to keep as much of the CO2 in the water as possible with little to no surface ripple/movement. oxygen exchange is at the surface. Water movement below the water surface does not equate to aeration in the tank. I tried to run all my planted tank water surface like a ripple across a shallow stream to help with the gas exchange. I don't worry too much about degassing CO2 because plants need O2 to consume the nutrients and CO2 as a source of carbon for building block. If they can't consume nutrients, they aren't using the Carbon source anyways. 

Roots is where the plants take in the oxygen, day and night. Any other parts of the plant, the plant take in CO2 during the day and O2 during the night.

AC 110 is the Hang of back, so you would have tonnes of aeration in the tank. XP5 is a canister. Unless you have a lot of surface agitation like the AC110 created, I am 99% sure your fish suffered from lack of Oxygen and not over dosed CO2.

pH test kit will registered a different number than a drop checker or a pH controller/monitor because when you shake the tube, you degassed the CO2 which in return will raises the pH level in the water.


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## pdoutaz (May 13, 2010)

THANKS for all thye replies - especially EDGE - that seems to make sense as I was concerned when I removed to 2 AC 110's. For the moment I have a small airpump and bubbler set up. Just trying to decide if I want to attach that to a timer for about 6-8 hours overnight, or if just angling the FX5 output towards the surface will do it...

Any thought on that option??

Thanks again to all the replied!!!!!!


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## EDGE (Aug 24, 2010)

angling the output upward will work as long as you can get a really good ripple. Just have to keep the water level high enough so the ripple doesn't become a geyser.


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## 2wheelsx2 (Apr 21, 2010)

That's what I do in my 125. But I have also taken to running an airpump or a powerhead with a venturi setup on a timer which comes on an hour or so after lights out until an hour before the CO2 comes on, in my tanks which have plecos That way I don't have to see the annoying bubbles or hear the noise during the day. This way, the CO2 is offgassed quickly when it isn't being utilitzed, and you also maximize the gas exchange to bring in fresh air. I started doing this as the weather got warmer because I had some problems with my plecos, and since that time, have not had a problem, even when the inside temps hit 30 C.


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## pdoutaz (May 13, 2010)

I think I like the way 2wheelsx2 does it, covers both options nicely 

Mods - please close this thread - Thanks All


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## VinnyD (Apr 21, 2010)

hmm might be lack of oxygen...i dunno tho...i had diy co2...the water turned a bit acidic...like overnight too...shocked some of the critters...decided not to add co2 thats not "regulated" with solenoid and yada....now the tanks all good


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## pdoutaz (May 13, 2010)

Thanks for the replies - based on multiple replies (on 3 diff forums) - it seems 2 factors were causing the problem. Lack of Oxygen and lack of biological filtration - have added an airpump on a timer for 6 hours overnight, when he CO2 and lights are off, and will be pulling an AC50 from my 30 gal to try and kickstart the bacteria again.
Feeling kind of foolish as I should have known better then to pull ALL the old filters off when I bought the FX5


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