Ditto to what rlederer said. I never have to top up water where i have a lid. Where i dont have a lid i can lose 1/2 inch of water per day.Ditto to what Aiken Drum said, but also consider a top for the tank. If the water is exposed it will naturally evaporate and the more exposed it is the faster it will evaporate.
Top up with whatever you use for water changes, presumably tap water treated with water conditioner.
Even though you might be topping up following evaporation dont think this is a substitute for water changes. Toxins in the water dont evaporate off with the water so get left behind, so you still need to do water changes to remove waste products like nitrate.
Once you are able to dose 2ppm ammonia and 24 hours later you see 0ppm ammonia and nitrite you are cycled.Okay, thank you! Im currently cycling my tank. Once my tank is done cycling do I have to do a water change to add fish or is it okay to add the fish as soon as I’m done cycling and have zero ammonia?
Aquarium heaters dont work like that. They have a thermostat. When the set temperature is reached they turn off. If the ambient room temperature is above the set temperature on your heater they simply don't turn on. So removing the heater during the summer months as suggested wont have any effect on the aquarium temperature as the heater should never come on in those circumstances. Turning the lights off would be more useful than removing/turning off the heater. Even LEDs will raise the temperature a couple degrees.Another note about evaporation. If you have a heater on, water will evaporate much faster. In the summer, especially if you live in a warm climate, you may not need the heater on and water won't evaporate much (this is all with a closed lid, of course. Good to have a closed lid, it keeps what's inside, inside and what's outside, outside).
Do you have a thermometer in there? Do some research on what temps for what fish you're getting. A thermometer will clue you as to whether you need a heater on or not, which will clue as to whether you'll be adding more water when you do your regular changes. I use the very simple and inexpensive JW Fusion Smart Temp Aquarium Thermometer in all tanks. It has an easy magnet that sits on the outside attracting the thermometer, which is on the inside with its own corresponding magnet. It looks like cheap plastic, is priced like cheap plastic, but it came recommended on some "best-must-have" aquarium site and by golly, they are accurate and work for years. Sold by lots of sites.