[fisherman]

Hi all,

I am going to start a new 300 gallon freshwater tank and I just need to know if it is necessary to add a CO2 with this big tank?

Do plants live in a tank without the CO2 injector ? If yes which plants ?

Thanks alot.

[Hoplosternum]

Hello Fisherman,

You would be better off asking at a more dedicated FW site than here probably. I am not really an expert but the answer does depend on what sort of FW set up you are going to have rather than how large the system is. While a large tank will have less surface area (for both CO2 and O2) to volume than a smaller one (usually) this is a problem only if you do not have enough surface water movement.

All my FW tanks have had plants in and I have never used CO2 injectors. However if you are going to have a very densely planted tank then you may want to consider one as well as fertalisers etc. A mix of plants and fish and you are more likely to suffer from too little O2 at night (when both the plants and fish are using it) than too little CO2. Powerheads or airstones (to agitate the surface for gas exchange) should solve this.

It is only a very dense true planted tank that really needs CO2 injections. I am afraid I have no experience of these. I would try another forum for that.

If it's just a few dozen plants (for a tank as large as yours!) plus a full fish load your problems are more likely to be low O2 levels at night, not low CO2 in the day.

Good luck!

[eses]

Like said above, it depends on how many plants you are going to have. From my experience, and from what I've read, your need for CO2 is dependant on your plant load. If your plants start sucking up your KH and dropping your PH you will need to counter it with adding more buffer and using CO2 to keep your PH low.

It also depends on your lighting, higher intensity of lights for more plant growth means more nutrients and co2 that will be required.

But alas, like also already said, you may want to find some people with a bit more experience and dedication to freshwater planted tanks.