Changing out the water completely

After tiring of trying to improve my water quality with additives and such, I decided to improve the basics; my water and salt. So I bit the bullet and bought an RO/DI unit today. I will also order some new salt. To this point I have purchased RO water from the grocery store dispensing machine and believe the purity probably varies more than I know. Also after reading I've decided that my "Reef Crystals" salt may be a "sink" for some of the elements we desire in our tanks rather than raising them. I'm going to give Tropic Marin Reef Pro a try. My primary problems are very low alk (4dKH) and low magnesium (890)but Calcium seems to be ok ranging btwn 440 and 480(a one time high).

My question is this: How best to begin to replace the 25 gal of water that is now in the tank, is 20% water change too much? How often can I do this?


Thanks for any advice or personal experiences.
Onjinsan

 

25% changes bout every 10 days IMO 480 CA just a touch high

 

Hi, this must be done slowly, like reef pointed out. 10-14 days would be an appropriate time span between changes. I like to reduce the stress as much as possible so I would do 15-20% water changes. You have a 30 gal. tank but your signature doesn't say if you have a sump. You have to calculate exactly how much water you have taking into consideration displacement for rock and substrate. This is important. After each change, check you water parameters twice a week while you wait to do the next change. All the water should be changed out after the 4th water change. Add live bacteria a couple times in the 6-8 week period you are changing out the water. You may double each dose.

 

Jed,
Thanks, my water volume is 25 gal ( I know because I had to pour it in a gallon at a time!)
So I will change out 20% about every ten days.