discus fish, water changes

Question
I'm reading and reading.......but I seemed to be getting more confused..........the water changes...........how can you change water (what percent) weekly in a 90 gallon tank.......and make sure it is the same temperature, ph, and all that......if this is a stupid question that the answer was in the reading, I'm sorry......but please help me.................do you have to have a 45 gallon holding tank or something............????

Answer
Hi Monna:  Things in the fish world do not have to be so exact as most of the reading implies.  Fish are use to a changing environment so as a fish keeper you only need to worry about getting it close.  The temperature should be within a few degrees, the pH within .5 of the tank pH.  For a 90 gallon tank I would change 10-20 percent weekly depending on the water chemistry tests.  Unless your tap water chemistry is off the charts then there is no reason you can not use your tap water and a water conditioner.  If this is still confusing just reply back to me and I will go into more detail... dave