CO2 and O2 injection posts

[JJP2]

Tom,

The last couple of days, you posted about injecting O2 and CO2 using a reducing T's (these are on PlantedTank.net). This thinking has me intriqued as I had thought about plumbing an O2 line into my CO2 reactor but was given feedback that would not be good.

I have several questions about them and thought this might be the best place to list them.

1. Are you suggesting that injection with the reducing is better than a reactor when a Cannister filter is used to drive the flow?

2. Will the CO2 mist or dissolve? Would this be decided based on the flow rate?

3. Will the O2 mist, buble or dissolve? Again would this be decided based on the flow rate?

4. Won't the excessive O2 bubbles cause the CO2 to de-gas faster at night, thus causing increased Ph swing which would result in more BBA?

Thanks,

John

 

[Tom Barr]

1. Yes, simpler and no flow related issues, might waste a bit more CO2 though.

2. Both, mostly dissolve generally.

3. Air is very insoluble by comparison to CO2. So bubbles and mist.

Adding aeration at night does not matter nor does pH due to CO2 change.
CO2 is not a salt like say baking soda which also can change pH or a strong acid which destroys bicarbonate(KH).

Fish are much more concerned about the TDS, CO2 will not chaneg the TDS of water, adding baking soda most certainly will.

When we add CO2, the pH issue is not very applicable.

BBA is an issue when CO2 is low when the lights are on, not off.
Low CO2/high O2 is good at night, during the day, high O2 comes from the plants and high CO2 from the CO2 system.

Regards,
Tom Barr

Regards,
Tom Barr

 

[JJP2]

Thanks, Tom. This clears up a few things, especially about BBA. Most posts indicate its a result of low CO2 but don't mention its low CO2 when the lights are on.

I'm in the process of upgrading to a 125 gallon tank and will be using a fluval FX5 and a Current Gamma 40 watt UV (got all really cheap).

By plumbing the O2 into the return, I will be able to reduce the turbulence at the surface from the outlet since I have O2 going in. This will off-set any increase in CO2 and could save some.


What are your thoughts on plumbing in the CO2 reducing T before a UV, thus having more dwell time to dissolve, the O2 after the UV since it won't dissolve well and out to the return?


Thoughts on spray bars vs the typical outlet?

Thanks,

John

 

[Tom Barr]

I keep surface turbulence right before it starts to break the water's surface.
So fairly high.

Aeration is at night only in addition to this.
You have a canister, you have no issues adding enough CO2 because all you do is turn the needle valve a bit more to account for any loss. Very easy and you lose hardly anything/cost next to nothing etc.

Yes, the Plumb prior to the UV is fine.

As far as the spray bar, I do not use them.
But you can get an idea based on the above about what type of moevement on the surface you want.

Do not worry about saving CO2, if you have enough current, the CO2 will mix well, CO2 is cheap and ain't gold. To account for the flow/surface movements etc, we add a little bit more, but this is only when the lights are on, 10 hours a day or so.

So it's not much "loss" and all the flow, surface movement and aeration at night helps the fish and keeps things pretty clean.

Regards,
Tom Barr