Oxygen And Carbon Dioxide Issues

[fry_lover]

a good friend came to see me today, someone very experienced with heavily stocked malawi set-ups, he commented that i dont have any specific air-pumps in my set-up and he thought there probably was going to be too much Carbon-Dioxide in my set-up.

It got me thinking, in non-planted set-ups is carbon dioxide a problem?

I think i will just add a powerhead to stimulate more water movement at the surface, after all thats the key isn't it? Thats the most effective way to drive off carbon dioxode and promote available oxygen for the fish?

None of the fish have been "gasping" but he also looked at my "other Rio 300" which is next to the Malawi and contains Parrots and other cichlids. Sometimes i notice if the current from my filtration gets too slow the fish will gasp (not rocket science as to why!)

So basically, today has re-inforced to me the important of strong water surface movement consistently for my fairly heavily populated tanks (especially the Malawi)

I have quite a few spare Fluval 3 and 4 Filters, i reckon its probably just as good to use them (without media) to agitate the surface of the water more? It is agitated, i know the importance of good surface movement, i just think it might need to be improved.

PS - it also makes me wonder if i am packing my Eheim Externals too full of media as i am not getting quite the desired "flow" from them really.

 

[afishdude]

use an air pump and airstone. thats the best way. but it also can look bad.

 

[dthoffsett]

I've found the key with overstocked tanks is to have abundant filtration. Filter(s) cycling the tank 6 or more times per hour work. Mine turn over the tank just shy of 10 times per hour, I have plenty of surface movement, but little to no splashing. So depending on what filter(s) you're using, the addition of the internals with just bio-media could be a good idea, IMO you can't have too much bio-media.

As far as the water flow slowing on your other tank, how frequently does this happen? Cannister filters should be able to go several months before slowing, if not, your waste load is probably too high for the filter to handle. Or, you could have too much filter floss packed in, I used the fine floss for water polishing in the past and found I had to rinse or change it every week, needless to say I quit doing that.

 

[fry_lover]

I've found the key with overstocked tanks is to have abundant filtration. Filter(s) cycling the tank 6 or more times per hour work. Mine turn over the tank just shy of 10 times per hour, I have plenty of surface movement, but little to no splashing. So depending on what filter(s) you're using, the addition of the internals with just bio-media could be a good idea, IMO you can't have too much bio-media.

As far as the water flow slowing on your other tank, how frequently does this happen? Cannister filters should be able to go several months before slowing, if not, your waste load is probably too high for the filter to handle. Or, you could have too much filter floss packed in, I used the fine floss for water polishing in the past and found I had to rinse or change it every week, needless to say I quit doing that.

i had some "performance issues" with flow rate BEFORE i added the floss as well, i think perhaps i am stacking the trays too full of media? I have a Eheim 2028 (rated for 600 litre tank) and a 2026 (rated for 350 litre tank).

In terms of ammonia and nitrite my filters are performing (not detected ammonia or nitrite in any of my tanks and i test weekly) i just find i need to help the "flow" along a bit by using internals (sometimes with out media).

the 2028 is supposed to be 1050 l/hour and the 2026 950 l/hour

The main thing is that (biologically) they are doing their job

EDIT: i am not a massive fan of the "how many times the filter turns the tank over arguement" altho i can see the sense in it...

but...

most if not all filters are "rated" for their flow with NO media in, let alone dirty media AND you could have a filter with a tiny filter "volume" that pumps fast, but the trouble is, the water doesnt stay in the filter long enough for the bacteria to do its job properly, therefore i believe the "turn the water over" argument is slightly flawed, although it is a factor i know.

 

[dthoffsett]

EDIT: i am not a massive fan of the "how many times the filter turns the tank over arguement" altho i can see the sense in it...

but...

most if not all filters are "rated" for their flow with NO media in, let alone dirty media AND you could have a filter with a tiny filter "volume" that pumps fast, but the trouble is, the water doesnt stay in the filter long enough for the bacteria to do its job properly, therefore i believe the "turn the water over" argument is slightly flawed, although it is a factor i know.

I'm well aware of that, which is why I advocate oversized filters. There are test kits that allow you to test the dissolved oxygen levels in your tank, why not take a more scientific approach and see what your levels are?
http/www.petsolutions.com/Dissolved-Oxyg...720201+C46.aspx

 

[Aphotic Phoenix]

If you know what your tank pH was before adding all of the fish the pH test can actually give you a guestimation on what your CO2 levels are...this is after all how many people determine the out-put of their CO2 injection systems, but it should work in this case as well.

Here is a handy link about how CO2 affects pH (with charts and such):
http/www.csd.net/~cgadd/aqua/art_plant_co2chart.htm