When you change water, unless the new water has been sitting in the open for several hours, you are introducing CO2 to the tank. This raises the level of CO2 in the tank for a short time, and that fluctuation in CO2 can trigger algae to start growing. Ten percent may be too small to do that, but why take the chance? Ten percent is also too small to do much in the way of resetting the water parameters, such as hardness, that topping off the tank for evaporation has changed. If you are still in the planning stages, and have access to a water line plus a place to drain water easily, you could set up a continuous water change system, that adds a dripping flow of water, with an overflow getting rid of the excess. That seems to work fine in my tank.