# Oxygen levels?



## Daz2162 (4 Jul 2013)

Hi guys, 
Is there a way of testing oxygen levels in the water.  Ive got co2 running and my drop checker is a good green colour but my fish seem a bit gaspy as of late,  cant tell if they're just chilling out or they're struggling to breathe. 
I have a little bit of water movement bit im not sure whats enough for good gaseous exchange. 

Is there a kit that tests  oxygen and is there a right or wrong amount? 

Cheers

Darren


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## Matt Warner (4 Jul 2013)

Hi, I'm sure Tetra do an oxygen test kit, I'm not sure how accurate it would be though. Is there much movement on the surface of the water?


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## Daz2162 (4 Jul 2013)

Cool okay,  I'll have a look for it in a bit. Yeah there is movement,  nothing crazy but there is movement.  My spray bar is submerged and pointing upwards, it doesn't make a splashing sounds but it agitates the surface.  Is this enough?


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## dw1305 (4 Jul 2013)

Hi all,


Daz2162 said:


> Is there a way of testing oxygen levels in the water.


Not really without some pretty expensive kit.


Daz2162 said:


> Ive got co2 running and my drop checker is a good green colour but my fish seem a bit gaspy as of late, cant tell if they're just chilling out or they're struggling to breathe.


They are struggling to breathe.


Daz2162 said:


> I have a little bit of water movement bit im not sure whats enough for good gaseous exchange.


You either need to turn the CO2 down or add some more surface movement, these both work in the same way by decreasing the level of CO2 in the water.


Daz2162 said:


> oxygen and is there a right or wrong amount?


 It isn't a simple case of enough or not enough, it depends upon all sorts of  factors. Have a look at this: <plecoplanet: Aeration and dissolved oxygen in the aquarium> it should give you a bit of back-ground information. I wrote it specifically for L. number keepers, but it is relevant for most fish.

cheers Darrel


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## Daz2162 (4 Jul 2013)

Ah cheers darrel,  thats a good read.  I just want to say that when i mentioned gasping i dont mean near death and not being able to breathe,  they're not at waters surface looking for oxygen and their gills are a good colour.  I just noticed that they were opening and closing their mouths every now and then just abit more than normal,  so hopefully nipped it in the bud before it becomes an issue.  Do you think itll be beneficial to move my spray bar along the surface to create more movement? 
I have a medium planted tank so would imagine they're pumping a little bit of oxygen out,  and my drop checker is a good shade of green.  What you think? 

Cheers

Darren


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## dw1305 (4 Jul 2013)

Hi all,


Daz2162 said:


> I just want to say that when i mentioned gasping i dont mean near death and not being able to breathe, they're not at waters surface looking for oxygen and their gills are a good colour. I just noticed that they were opening and closing their mouths every now and then just abit more than normal, so hopefully nipped it in the bud before it becomes an issue. Do you think itll be beneficial to move my spray bar along the surface to create more movement?


Yes, I probably would, hopefully your fish should become a bit more active and have less rapid gill movements. This isn't really an oxygen effect, it is because the CO2 will out-gas more efficiently.


Daz2162 said:


> I have a medium planted tank so would imagine they're pumping a little bit of oxygen out


The plants will have fully oxygenated the water during the photo-period.  We use the tank in the lab to give us a rough idea of whether the membranes on the DO meters are OK, following calibration assuming the meter reads about 7 mgl-1 the membranes is all right, if it doesn't we are about £100 worse off. High levels of oxygen help, but this is really a CO2 issue.


Daz2162 said:


> and my drop checker is a good shade of green. What you think?


 I'm not a CO2 user, and others will have different advice, but I'd turn the bubble rate down.

cheers Darrel


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## Daz2162 (4 Jul 2013)

So during my 9 hour photo period my plants will fully oxygenate the water column? I noticed this fish behaviour this morning when my lights were off,  could that be why then?  Maybe an air stone to be used for a few hours at night. 

Really appreciate all your advice mate,  very helpful. 

Cheers

Darren


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## dw1305 (4 Jul 2013)

Hi all,


Daz2162 said:


> I noticed this fish behaviour this morning when my lights were off, could that be why then?


Yes that is it, CO2 levels will have built up over-night when all the bio-load (including plants) is respiring. If the CO2 comes on before the photo-period, and you have higher residual levels of CO2, the fish may be stressed. As soon as the light is on ("above photosynthesis light compensation point") the plants are using CO2 and producing oxygen.


Daz2162 said:


> Maybe an air stone to be used for a few hours at night.


You can do, or you can increase the surface ripple.

Have a look at this thread: <Surface Agitation | UK Aquatic Plant Society>

cheers Darrel


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## Daz2162 (4 Jul 2013)

Just read the suface agitation thread.  It summed up everything that you have just said. 

Thank you so much for your help darrel.  I'll be asking you allsorts now! Haha


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