I normally do 10% a week. However my wife and I were out of tow 3 out of 4 weeks, came home and got caught back up in life (kids, dogs , family…) then BJD. So it’s been 6 weeks, so I was thinking 50% of the missed water changes. On a side note I have an ICP test here and I am curious what has been depleted in this time. In July I am consolidating all my stuff into one tank that will be about 450 G system. I’m toying with the monthly ICP and simply replacing what’s missing. I’m going to have to go read up on that.