Re: Water temperature and fans

> >To lower temperatures, a simple fan can be more economical than a chiller.
> I have been talking about this to others and the question I asked was should
> you blow air ONTO the water surface or AWAY from the surface?

The question doesn't mean much since you must have air circulation
near the surface of the water; you are blowing air onto or across the
surface of the water and at the same time away. The more turbulent
air flow near the surface of the water, the more evaporation will
occur which will lower the water temp below ambient room temperature.

> I can get up close to 40 degrees C (38 is probably the
> hottest that I can remember) without any noticeable effect on fish or plants.
> What evidence is there to support the theory that this water temperature is
> bad?

It may be fine in your circumstances. It really depends upon the species of
fish, the types of plants and the amount of dissolved oxygen in the water.
If the plants you are interested in are growing ok, then I wouldn't be
concerned. There are several temperate plant types which won't grow under
hot conditions however these are not commonly sold since the majority of
tanks are kept at tropical temperatures.

The higher temperatures can affect the amount of dissolved CO2 and O2
in your water since these gases will diffuse out of the water faster
with higher temperature. The higher the temperature, the lower the
concentration of a gas in solution at equilibrium.