Most odd ball problem you have found with your tank

[afamousjohnson]

I have been having multiple issues with my system this year. Its easy to be said as there has been 2 tank moves over that time - new lights - new flow - new this new that.

Despite the changes I am still having coral issues and looking for culprits. We all know of the pests, changes in a quick manner, or just bad water params and matienence care.

But what are some odd ball problems folks have been able to put their finger on?? Say a pump leaking crud into make up water - containers leaching - a fouled line - etc. etc etc
Just looking to get other angles not thought to look at that others may have already stumbled upon.
Or say a dollar store air freshener the wife put under the tank to try and help it smell like roses lol if you can smell it well it is in the air - hmmmm close to my skimmer air inlet... hmmm see like that. prolly couldnt put my finger on it but if removed and over a short period probs subsided it would have to be a variable.

so what are some odd ball out of the norm variables folks have found when having tank issues.

 

[Waters]

The weirdest issue I have had is a knocking noise coming from my sump. After hours with my head stuck under the tank, plugging and unplugging things.....rearranging pipes, etc. it was traced to an Aqueon heater. Still not sure why it was making the noise (one R2R member stated it is due to hot water being "trapped" against the acrylic?) The noise did go away if I left the heater floating in the sump and not suctioned against the acrylic. I was able to trace the noise to only when the heater was on so it proves the hot water trapped theory I guess. Still makes no sense to me o_O