I thought that if some of you haven't seen it, that you might appreciate it too. The Java-based Reef Chemistry Calculator is a very popular site for DIY-chemistry people, but they also have one for Ca reactors. Reactor Setup help Here is a picture of my values typed in to show as an example. With a system volume of 125g and of course daily testing, I know that I typically supplement my tank with about 2.5tsp of buffer to keep my dKH where I want it. After setting up my reactor and testing my effluent water, it's dKH was 30 of which I was returning to my sump at a rate of 40 drips per minute (dpm) that comes to about 2ml (just an estimate because NO drops/droppers are identical). Coupled with my initial tank dKH of 11 it tells me that if I do NOT adjust the dKH of my effluent water that I would have to adjust my dpm or rate of flow to equal 19.3ml/min which would of course be too many drips to count, but could be measured nonetheless. You DO NOT have to complete both sides of the equation to get values, I just filled in both sides to see if my calculations on both sides were going to be equal and they only differed by .1ml - I can live with that. Now, I know that this is JUST AN ESTIMATE and that the reactor will still have to be adjusted as corals continue to grow or additional livestock is added, but this is still a nice little java-based reactor calculator that was a treat to find. For those who are always the nay-sayers - I believe that the calculations are based on Dr. Randy Holmes-Farley as denoted at the bottom of the site.