So it may sound weird but Im a Floridian and I go to the beach A LOT. So I know the taste of saltwater. So after 21 years of playing in the surf I know about how salty ocean water is by the taste. So...I always poke my finger into the tank to guage the salinity along with my hydrometer...its like a back up...and this may sound weird to most who dont surf but I actually love the taste of fresh salt water....its so clean tasting. Anyways last night I tasted the water while hydrometering and the water was bitter as crap. I was like.....ewwwwwwww. So I measured ammonia, nitrites nitrates and all the usuals and everything was perfect. My tank is in the middle of a red algae outbreak so I guess that may be contributing. So then I turned the filter on and smelled rotten eggs. To my dismay I realized I hadnt used the filter in weeks......you can put two and two together. I didnt realize saltwater stagnated that quickly.