I just did some testing tonight and need a little advise as to where to go from here. dKH: 10 Ca: 420 Mg: 1350 pH: 8.3 NO3: 20 My tank went down for three days. On Monday, there was a leak. On Thursday, it was fixed, feeding resumed and I am still trying to tinker with my skimmer to get it to work right. I do use RODI water. Last Sunday, I did a 30% water change and ended doing about the same on between Thursday and today. So that's my story and I am sticking to it. Anything I should do looking at the numbers?