I think it will be alot better as when i do water changes it drops my levels a little, add that to the fact that it does drop fast anyway and you have an extra low reading. Then you have to add extra calcium, mag, etc to bring it back up which costs more money plus the fact that when your levels are lower it takes longer to bring them up. But still you ave a good point is it cost affective. If nothing else it might save on time and effort.