Carbon dioxide

[Rob-Rah]

I have been reading up on CO2 dissolved in water (you know, the way people do...). It creates a weak solution of Carbonic acid. Some of the CO2 creates this acid, whereas the vast majority of the CO2 is merely suspended in the water as CO2.

I don't want to play with other acids or CO2-injectors if I don't have to, for my aquatic utrics and Aldrovanda. I was wondering what people thought of the idea of simply pouring some supermarket bottled carbonated water into each tank every so often (not much, just a bit - I don't want to go overboard on the Ca/P/Na ions added [is there a mineral-free carbonated water on the market?]). This stuff is simply a solution of CO2 in water with extra CO2 added beyond what can be held in solution. Sounds ideal to me...

Any thoughts?

[Tim]

Rob, I lost my Aldrovanda last year, but this year, the new one I got is growing quickly and happily. The difference is from a tip I got from a commerical grower. He said to occasionally pour old water from your plant trays (with some decaying matter that's always on the bottom of the trays) into the Aldrovanda container. I've been doing this, and you can see bubbles coming up from the bottom of the Aldrovanda dish. I know that doesn't answer your question, though.

[Bob H]

Rob if you want to add carbonated water why not get a Soda Stream and make your own, using Rain water?? I'm not sure there is enough carbonic acid in carbonated water to make much of an effect though, after all acid rain isn't THAT acidic is it? No where near 4 or 5 pH??

If you do experiment, please let as more timorous beasties know how it goes.

[Cromp]

Hi Rob,

If you pour carbonated water in your Aldrovanda tank, the dissolved CO2 will quickly dissipate into the atmosphere. The part "beyond what can be held in solution" will vanish almost immediately. If you put organic waste in the water this will decompose and release CO2, like Tim says. Rain water has a pH of 5,6 due to the dissolved CO2 as carbonic acid.

[Rob-Rah]

The idea isn't to increase acidity with Carbonic Acid - that is better done with peat-tea, I think. It's to provide a source of CO2 dissolved in the water - which Aldrovanda in particular is said to appreciate. For people with a chemistry bent, the equilibrium equation lies well to the left, meaning that acidity (concentration of H+ ions) is very low:

CO2 (aq) + H2O (l) -> <- H+(aq) + HCO3-

Acid rain isn't acidic becuase of CO2, but mainly becuase of SO2 (produced during combustion of many organic materials, which forms sulphurous (H2SO3) and sulphuric (H2SO4) acids on solution in rainwater).

I am starting experiments with U gibba in various concentrations of tea this year, green and black. This ought to hinder algae, but I don't know what the other chemicals present may do. What with this and soda-stream Aldrovanda, I hope to present a cocktail of results later on (pun, pun).

Anyway, any more ideas on fizzy water? I didn't know you could still buy soda streams to be honest, I assumed they were a part of my lost youth...

[Bob H]

Why not just aerate the water? Little airstone and pump, increased air/water contact = increased gaseous exchange.

[Binataboy]

Adding soda water to the container will work... sort of... I have heared of this before however the water must be added regularly as the CO2 is lost fairly quickly. In my opinion not worth the effort

CO2 acidifies the water so make sure you have Carbonate Hardness in the water or you can bottom out your pH.

The easiest way to add CO2 is with a yeast reactor, simple and cheap, just don't add to much yeast and watch your KH (Carbonate Hardness)and pH levels.

Airateing the water with an air stone will stop the CO2 levels bottoming out so is recomended in tanks with no "animals" to produce CO2 although CO2 is very soluble so standard surface exchange is usualy good enough if there are not to many plants. You will generaly get better growth with added CO2.

George