Need help figuring out the cause ...

[hobogato]

wish i had seen this thread 4 weeks ago! this is what i would have said to do - the leather corals you have could be causing the problems you were seeing and the carbon helps remove the toxins they release. the other things you are doing are probably helping as well - glad you got it turned around

- ran carbon every week

[aquasport24]

What kind of vinegar are you using?

[eleyan]

just plain old HEB distilled white vinegar. I have a 6G top off water container that I fill up every three days. I add 8 table spoons of kalk and 210 ml of vinegar and let gravity do the work