so my town has used chloramines for years now. when I got into keeping freshwater fish a while ago, I had no problems simply dechlorinating the tap water and adding it to the tanks. for over a year this has worked well for me.
however, today something happened in my 2 month old 20g long cycled reef tank that shocked me. after one of my shrimp was sucked up by the HOB filter on the tank, I removed it and performed a 25% water change with normal RODI water from my RO Buddy unit mixed with instant ocean salt to remove any ammonia or excess nutrients, just to be safe. later that day, I returned to the tank to find something terrible happening. my fish and CUC were all ok, but my 5-6 soft corals and my acan were all closed up. I performed tests for nitrite, nitrates, ammonia, and PH and found ammonia at 1 ppm. I was so confused and ran a test on my RODI water. turns out it was letting ammonia through the unit! I assumed it was chloramines and was glad to have found the root of the issue. I quickly dechlorinated the tank water, my ammonia dropped to <0.25 ppm, and I'm hoping my biological filtration is still intact. my fish all seemed fine after this, with a few corals even showing signs of re-opening! I was relieved that my very first reef tank seems ok, at least for now. but I have a lot of questions. what happened to the RODI water that has been chloramine-free for 2 months? I ordered a TDS meter and it should be here within a few days just to be able to more closely manage my water quality. what can I do to ensure my water quality is safe for my tank? is there something I should know about RODI units? and why did this happen now? I recall my RODI water smelling a tad funky today, but that's all that was out of the norm for me. all input is greatly valued.
however, today something happened in my 2 month old 20g long cycled reef tank that shocked me. after one of my shrimp was sucked up by the HOB filter on the tank, I removed it and performed a 25% water change with normal RODI water from my RO Buddy unit mixed with instant ocean salt to remove any ammonia or excess nutrients, just to be safe. later that day, I returned to the tank to find something terrible happening. my fish and CUC were all ok, but my 5-6 soft corals and my acan were all closed up. I performed tests for nitrite, nitrates, ammonia, and PH and found ammonia at 1 ppm. I was so confused and ran a test on my RODI water. turns out it was letting ammonia through the unit! I assumed it was chloramines and was glad to have found the root of the issue. I quickly dechlorinated the tank water, my ammonia dropped to <0.25 ppm, and I'm hoping my biological filtration is still intact. my fish all seemed fine after this, with a few corals even showing signs of re-opening! I was relieved that my very first reef tank seems ok, at least for now. but I have a lot of questions. what happened to the RODI water that has been chloramine-free for 2 months? I ordered a TDS meter and it should be here within a few days just to be able to more closely manage my water quality. what can I do to ensure my water quality is safe for my tank? is there something I should know about RODI units? and why did this happen now? I recall my RODI water smelling a tad funky today, but that's all that was out of the norm for me. all input is greatly valued.