The problem with filters is that they concentrate the smell between changings. Also, in my distant past I was into tropicals in a big way, as was my dad, and found that under gravel filters simply didn’t work well, if at all... They concentrated poop under the gravel and made for some pretty smelly tanks.... Also, I really advise against getting piranha....it will be a passing fancy at most and will likely piss off your co workers....if you care....

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...Tracy

'00 ML320 "Casper"
'92 400E "Stella"