I will try and make this as short as possible. I have a 125 gal DT and over the past year it has gone down hill. I always have this brown blanket like covering on my rock. It seems to coat everything and has bubbles on it. I have been dosing hydrogen peroxide for 4 days and I am not seeing any results. I need help in identifying the problem as I have tried things over this past year an it always comes back. If I lights out the tank for 3 days the slime/algae is gone but turn the lights back on and it is back within days. Over the past year I have tried GFO, weekly 35 gal water change, slime remover don’t remember which one and lights out several times. Unfortunately my test kits for ammonia nitrite and nitrate are out of date but in the past they have always been fine. I have never tested for phosphates. The tank has been up for approx 2 years but half the rock came from a 10 year old smaller tank and half was dry base rock. I am at my end. This algae has killed numerous of my corals. I would scrape the whole thing but fish are healthy. Please help. I can will answer any questions or provide more photos if needed. This sits in my livingroom and is an eyesore at the moment....it must be fixed. Source water is RODI made in garage with IO salt.
