Help required with an aeration puzzle please.

[shawn barker]

I have a planted 500liter discus tank that I inject CO2 into at about a bubble a second during the lights on phase only. This maintains a concentration of about 16ppm which according to "Chuck's Planted Aquarium Calculator" is good (pH=6.8, kH=3.4degrees). (see the link below)

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

Anyway the plants all seem to be fine, pruning back once or twice a week and the fish seem in good health.

On with the problem(?) I think I need to increase the aeration within the tank to incease the oxygen levels as the fish have started to ocassionally gasp near the surface. I don't want to agitate the surface as this would negate the injection of CO2 so...

if I use an air pump and pump air into my CO2 reaction chamber would this raise the oxygen level within the water whilst, at the same time, it increases the CO2 concentration? :idea:

My reaction chamber consists of a gravel syphon unit connected to the outflow of one of my filters and the CO2 unit. I used the top from another syphon unit to make a bottom to it so I could connect an "L" piece and a spray bar so water exits the chamber just above the substrate and this setup seems to work very well.

Sorry about the length of post :shock:

[Phlipper]

Putting air into your reactor will negate the Co2 effects completely, even more so than surface agitation. I think the main key in maintaining good oxygen levels in a Co2 injected tank is to have lots and lots of plants which through the process of photosytheseis oxgenate the water, plant very thickly !

I have a similar setup, with lots of fish in a 6 foot tank with no problems at all, my spray bar is at water surface so as the surface water is moving but not splashing, this seems to be the happy medium for plants and fish. I also do 50% water changes twice weekly as is reccomended for discus, this also helps boost oxygen levels for a day or two anyway. Maybe the fish appear to be gasping for another reason ? maybe more water changes are needed ?

[shawn barker]

Thanks very much for the advice.

I wasn't sure about the air pumped into the reactor as I had never heard or seen anything else about it...obviously, that would be the reason why.

I tend to do 10-20% water changes 3-4 times a week and the fish seem to be more active after these.

Someone else adviced reducing the amount of CO2 injected but this would lower it to the point of being pointless(if that makes sense). At the moment I have NO surface movement and rely on an improvised surface skimmer to keep the surface like a mirror, therefore I shall twist the spray bar a fraction and see if a little movement helps.

At the moment I have plenty of plants as you can see, but could maybe squeeze in a few more...if my wife lets me!!



Have just moved the large piece of bogwood to a more central position...what do you think? Needs the plants to grow around it a bit more I think.