I wanted to know if Ammonia, Nitrites, and Nitrates evaporate in a fish tank when the water evaporates, or does the concentration get stronger as more water evaporates.

How much can ur tank evap? Unless u dont change ur water for like 1 year

As your water evaporates, the concentration of all three will increase. That is, they won't evaporate with the water. Of course as was indicated above, the amount of evaporation (as a percentage of your total tank) is relatively small, so the solutes in the water will increase in concentration only slightly.

Dennis

the amonia, nitrite, and nitrates dont evaporate. thats why just adding water isn't the equivielent of changing the water. the concentration gets stronger.

Actually, in fact- the ammonia - a portion of it does gassify if you have a well aerated tank.
Eric