Sorry please don't hijack this thread, OP 's questions were regarding their situation not debating the effectiveness of a tester. I differ from your opinion but this is not the thread to do this in. Op how is your tank doing currently, are your fish recovering and doing better? Vinnies point is right a small goby wouldn't make too big an impact, especially if you searched and found 0 remains. Your cuc most likely made short work of it. How is your CUC? I found after the first year, hermits become the devil. As they grow they lose their taste for pest algae and then learn to rely on food they catch from feedings. As they grow their tiny shells are useless so naturally they start killing your snails for their bigger shells. Its a matter of a month or two and I realize I get lots of algae building up because my cuc is also no more.