I can only tell you my experience.... I change the water 2 times a week (25%) in all of my shrimp tanks. All of the species breed very well for me and I do not think that there are any negative effects of doing a water change. However, you can definitely cause problems with doing a water change if you do not do it properly... i.e. trying to mix hot and cold to match tank temp...not using dechlorinator...etc.