Here's the myth debunked simply. It doesn't matter what your pH is. Fish will survive and thrive in any pH. Trying to make perfect pH is the worst possible. Consistency is much better. If your pH out of the tap is consistently 6.2 or 8.4 ( for example ) and you do daily WC's, there's no problem. If you need to age it for a day to match the tank of 7.3 ( example ) that's fine also. There's nothing wrong with tap water as long as it's consistent.
As far as the bb goes, it's all ( 99% ) in your filter. If you looked at both my pics you can see I keep a bare bottom also. With every WC, I wipe down ALL the glass surfaces inside as they do get a slimy buildup. You're just not gonna lose any volume of bb unless you do something drastic like change all your filter media at once.
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