Hello, i have a question about water changes and cycling that deals with evaporation.


Well, my tank is about 2 weeks old. i just did a 25% water change bc i had a bit of ammonia and nitrite. My water is fine now and has no nitrite and no ammonia, but a bit of nitrate; around 20,30 ppm. however, since my tank is only 2 weeks old, and i want to have my cycle done, my water evaporates pretty fast. I would just like to know if its safe to just add a gallon or 2 after the water evaporates for quite some time. of course with aqua safe and some cycle product. keep in mind i have a 2 week old tank and my cycle is not done yet. also, how do i know i have established a biological filter. I know its once i get 0ppm ammonia/nitrite and like 20-40ppm nitrate. but that can be caused by a slight water change or/and cleaning up some excess food/waste.


please let me know about if its safe to add water after evaporation and about how i know when the cycle is complete.

You are always going to get evaporation in a fish tank, it is unavoidable. If you notice the water level has gone down slightly, just top it up again. It is perfectly safe so don't worry. It's going to be a few more weeks before your tank cycles properly. It obviously depends on how many fish you are cycling the tank with a how quickly ammonia builds up. But like you are already mentioned, a fully cycled tank will have an ammonia & nitrite reading of zero, and you will have nitrate present. What you got to remember is when a tank is newly cycled, the biological filter is quite delicate. Also, don't make the mistake of piling lots of the fish in a newly cycled tank, this will only result in an ammonia spike. Fish must be added gradually over a period of a few weeks.

My friend went on hols for 2 weeks and i was given the job of feeding his fish. He always leave his lid open a bit (dont know why) and the cover glass open a bit. I was amazed at how much water he lost in the 2 weeks. A good cover to your tank will reduce evaporation. If you get evaporation then just top it up, just dont forget to use the dechlorinator