My swfo tank is fully cycled, yeeepeee, all readings are 0 no2, 0 amo, 80 ph, 5.0 no3. How much water should I change on the first water change? I have read 50-100 percent? That's alot of water, any suggestions on my 215g tank? Also, do I clean and thus disturb my 4" dls bed?Any suggestions would be much appreciated.