The worst thing I have to deal with on a regular basis is the fact that my tapwater is full of phosphates. Because of this I have a bad cyanobacteria (blue-green algae) problem. I have to pick it off my plants and gravel on a weekly basis. That turns a 1 hour water change into a 2 and a half hour job. Also, as my tank is a 400 litre jobbie I have to change 10 10 litre buckets of water at a time. All that temperature adjusting and dechlorinating and knowing that I'm adding tons of phosphates to what is, by no, a phosphate free zone. I don't have any room for a RO unit either. Grrr.
The best bit is coming home from work all stressed to the eyeballs and spending 20 minutes just looking at the fish going about their fishy lives. So relaxing!
WK