Hi, for some unknown reason I decided to smell the air above my tank today and it was reeking (the fish were swimming on the top too). It smelled like hydrogen sulphide and methane (rotten eggs, swamp gas type of smell). Is it possible that the gravel(eco-complete+flouritemix and a small amount of epoxy coated gravel(~0.5-1lb) for added volume on a terraced part) may have undergone that anaerobic thing? I also realized that I had used cotton pads once in my HOB filter and then left it there, forgot about it, for more than a month. Also, I did some heavy feeding the last few days, with frozen bloodworms, frozen brine shrimp and live BBS, I dont recall any more food going uneaten immediately, than normal. I had to leave for work but I plant to completely change the water, refill and empty again, this evening and was looking for suggestions/pointers to the problem and how to combat it. Thanks!
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