Re: Bubbles during water change

>Subject: Re:  Bubbles During Water Changes
>> This very same bubbling occurs in all 3 of our plant tanks every time we
>> do a water change - new water is 100% DI reconstituted and stored for 1
>> - 3 days before use.
>The same thing happnes in my tanks after a water change.  Does this 
>happen to everyone?  It seems like it does.  In the latest issue of FAMA a 
>man said he has this happen to his tanks.  He tested his tap water and 
>claims it is high in CO2 and its the CO2 from the tap water that causes 

IMHO, the bubbling is could be caused by dissolved gases _or_ new nutrients.
And the dissolved gases can very well include CO2. When water is changed in
a tank without plants, expecially in the winter when cold water dissolves
move air, you will see bubbles form on the glass... even on the fish. The
dissolved gas should also include more CO2 which I think make up around 3%
of air at sea level. You will also see the effect of temperature on
dissolved air if you mix some hot water with the cold from the tap.  I put
my tap water directly into the tank and I then see a mist of bubbles coming
out of the hose.  

Afterwards, however, in a plant tank you will often see more than bubbles
sitting on the plants and glass .... you will see bubbles eminating from the
plants.... the so-called pearling effect due to increased photosynthesis
under O2 saturation. It seems that if the new water causes the O2 levels to
go to saturation, the photosyntesyzing plants will start to pearl... If all
nutrients including CO2 are already sufficient, then I would conclude it is
caused by the quick achievement of O2 saturation. On the other hand, in a
tank without CO2 injection... the extra CO2 which dissolves very quickly can
give the plants a little boost. Together with new nutrients which could be
coming from the tap water, any limiting nutrient (including N) can be
replenished which would also help the plants to photosyntesize more quickly.

I think that the two potential causes *(nutrients vs. other dissolved air)
might be investigated by timing a water change after fertilizing the
plants....or by first shuting down any injected CO2... or by doing it first
thing in the morning before the plants are active.

>  It was FAMA so I would take it with a grain of salt.

Sometimes the problem lies with the author, not the magazine. I don't think
that  FAMA is the only magazine that is guilty of printing incorrect
information. We find misinformatin in many aquarium books as well.

Neil Frank      Aquatic Gardeners Association         Raleigh, NC