C0 2 And Aerators Together?

[weathermen]

Hi all
I have read an article saying that if you are injecting C0 2 into your tank it is pointless if you have a bubble aerator as well, turn of aerator when c0 2 is injected once it has dispersed then turn on aerator! As anyone ever heard this??

 

[njw]

Surface water movement/disturbance accelerates the removal of co2 from the water. So an air stone will aid/accelerate the removal of co2 - running them together probably is pointless!

When people inject co2 for plants, in heavily stocked tanks the injection should be stopped at night (plants produce co2 at night, not consume it) as you run the risk of suffocating your fish. Some people use an air stone at night to inject more o2 to balance the tank, usually when they use co2 systems that cannot be easily controlled/regulated (like DIY kits, yeast systems etc).

 

[Wonderboy]

Surface water movement/disturbance accelerates the removal of co2 from the water. So an air stone will aid/accelerate the removal of co2 - running them together probably is pointless!

When people inject co2 for plants, in heavily stocked tanks the injection should be stopped at night (plants produce co2 at night, not consume it) as you run the risk of suffocating your fish. Some people use an air stone at night to inject more o2 to balance the tank, usually when they use co2 systems that cannot be easily controlled/regulated (like DIY kits, yeast systems etc).

I use an aerator at night and co 2 during the day. Works great for me. I know that my plants can put out aenough oxygen during the day to keep my fish breathing, but at night, I feel better putting in more oxygen mechanically to make up for all the day time co 2. It's really a matter of what you feel like rigging up.

 

[ncjharris]

Just a quick reply. I seem to remember reading somewhere that the levels of o2 in the water and co2 are mutually independant - that is running both a co2 injection system and an airstone will have no effect on the co2 level.

I think - let me see if I can find the article to back this up.

I also seem to recall that unless you are using a HUGH amount of co2, you won't suffocate fish with a co2 injector.

brb......

EDIT:

Thought so, check here
http/www.####.co.uk/Diyco2.htm

there is another article I read somewhere. Its the pH that is important to monitor with regard to o2 & co2

 

[Ptarmigan]

.

 

[Bloo]

Certain websites are "banned" from linking here and will appear as #### with an autoscript.

If you really want to find that article, do a google on Diyco2.htm

 

[Ptarmigan]

.

 

[ncjharris]

Certain websites are "banned" from linking here

Well I didn't know that! Shows I should check my posts after I write them!

Who chooses? or is it automatic?

 

[chrismr]

Thanks Bloozoo2, yep I am understanding now !

Let me see if a link I found to Henry's Law will be accepted :
http/en.wikipedia.org/wiki/Henry%27s_law


edit later
Yep that looks good and tests out ok

Can someone read that and put it into english. Am so bored at work that my brain has completely shut down...

 

[Bloo]

Who chooses? or is it automatic?

The higher powers that be

 

[andywg]

The dissolved levels of oxygen and CO2 are independant, but that is not the issue here. The issue is the increased surface area/agitation provided by the airstones meaning increased gas exchange which results in a lot of the CO2 you are injecting into the water dissipating into the air.

The real problem with co2 is the plants. Once the light is off the plants become aerobic, that is they consume oxygen and exude co2. This is why you should not rely on plants for oxygenation and also when people keep big fish they do not have the tank planted (as the larger fish require more oxygen).

Essentially there is a choice, big plants, or big fish?

 

[iggy01]

This topic has been debated quite a lot recently on planted tank forums.

My personal belief is if you are using pressurized CO2, there should always be a certain amount of surface movement. Yes, when plants pearl during the lighting period there is plenty of O2 available. But, as andywg stated, things change at night. Having a bit of surface movement won't cost that much extra in CO2 anyway. Some people have no noticeable surface movement and inject CO2. If you don't create agitation at night in these circumstances you may be asking for trouble. I've seen countless posts on forums from people who inject CO2, wake up to a tank full of dead and dying fish and blame the CO2. Sure, sometimes the CO2 is to blame, but sometimes it may be due to a lack of O2.

Here is part of a post from someone who tested the dissolved oxygen levels in his planted tank

"I dug out some dissolved oxygen (DO) numbers for my 29g jungle tank that can provide a bit of numerical perspective. The tank has pressurized CO2 with no surface agitation, good internal flow, low pollution, and is moderately overstocked. It’s covered by a glass partition such that there’s a 1/2” strip in front and 3/4” strip in back open to the atmosphere. I run it a bit cool, at 72F => saturated DO ~8.7ppm .

4wpg lighting
a) morning ppm 6.6
evening ppm 13.7
next morning ppm 6.6 (no overnight aeration)

b ) morning ppm 7.4
evening ppm 13.0
next morning ppm 8.2 (continuous high level overnight aeration)

c) morning ppm 8.2
evening ppm 14.8
next morning ppm 7.8 (continuous modest overnight aeration)

2wpg lighting
d) morning ppm 4.1
evening ppm 6.9
next morning ppm 4.1 (no overnight aeration)

It's obvious that when photosynthesis is really kicking during the day (a,b,c), DO is high the next morning. It’s significantly higher if overnight aeration is provided however. Under conditions of low light reduced photosynthesis during the day (d) DO is quite low the next morning. If the tank were even more overstocked, more polluted, or covered, DO would be even lower under low light, possibly approaching dangerous levels for the fish. DO concentrations of 5-6 ppm are generally recommended for good fish health with saturation levels possibly even better. Fish are severely stressed at <2-3ppm and will die at <1ppm"

HTH.