Been using IO for 5 years now, never had any problems. Tried Kent once, we had a group buy with great prices, slowly swithed over and all my SPS started to bleach. Had to take all of it out of my 150g and put it in a friends tank (10g) while I switched back to IO. Mixed up 320g in two weeks to get tank back on track. Never again will I sway from what is working in my tank.