I agree, lots of water changes are extremely helpful for growth and overall health, however, not all at once. For example, I will do roughly 100-150% per week, but it's in the form of 50% at a time, every 2-3 days. This way it's not as much of a shock on the tank, but I still keep constant fresh water at all times. Not doubting 90% hasn't worked, just sharing a different view. Nice terror, too, by the way!