Ok, long time member but back posting from awhile away. I have a 125 Gallon 300+ gallon system with Refugium and sump and deep sand bed, that seems to have lost it cycle. Yeah I neglected it for awhile my bad, fish are doing great, but corals and anemones aren't, I stopped adding anything and got myself back on track, after the neglect now. But curious how do you re-establish the nutrient cycle in an established tank, fish and most inverts are doing great. I don't want to rush things and kill everything but need to get things back to how they should be. Tank is a bit on the acidic side and is why I think fish are ok, the salinity is low and just starting to raise that slowly. I did order some bacteria to see if that works (MicroBacter7 - Complete Bioculture - Brightwell Aquatics) saw decent reviews. Anyway thanks in advance for your comments and help.