When planning an aquarium setup, many folks forget to think about evaporation, and just how much of it their layout and equipment choices will cause. For open top aquariums, evaporation can happen at rapid rate. Throw in some high intensity lighting or energy intensive pumps, and you only hasten that evaporative rate. Fans don’t help either, as they help induce evaporative cooling. Combining all of these together, you might experience a loss of several gallons per day, forcing you to top off frequently or to add an auto top off device to your setup. Fortunately, there are little things you can tweak to change the evaporation rates.
By using lower intensity lighting (e.g. LEDs) or switching to pumps that consume less energy, you lower the amount of energy entering the water, thereby also decreasing evaporation. If buying new pumps or lights isn’t an option, try cutting back on how long they run during the day, or even shift their usage to the evening hours. Using a less open design also helps. Canopies and aquarium braces aren’t always the most attractive aquarium accessories, but they do slow some of that evaporation at times.
If too much evaporation is an issue, we recommend trying the advice above. If none of those alleviate the issues, an auto top off may be necessary.