Smuts on the substrate- good or bad?

[GreenCircleGirl]

The smuts or gunk on the substrate, is it good or bad? I hate the gunk that flies around when the substrate is stirred, so I over filtrate and vacuum. Is there any benefit for planted tanks? Should I be working so hard to get rid of it in planted tanks? 

[Tihshho]

Smut? I'm not sure I follow. If you're talking about detritus it all depends on the tank and the fish. Some species thrive with detritus, others who spawn in the tanks and rear their young also can benefit from detritus as it's food for microorganisms fry can eat. In terms of a planted tank, detritus breaks down and ends up being food for the plants. If you're getting a lot of build up your tank is either being over fed, has a ton of pest snails creating waste, or you don't have adequate flow to stir up waste on the surface of the substrate for filtration to pick up. 

[GreenCircleGirl]

It is a 40 gallon breeder with aquaclear 70 HOB and 2 sponge filters. How can I increase circulation across the bottom?

[Tihshho]

A powerhead is a great solution for flow. If there is a specific area that is getting to much mulm buildup, you can aim the outlet over that area (not at) then the flow will prevent the debris from settling. IME sponge filters are not great for debris collection, so your AC70 will be the power house doing that work. Until everything is stable in terms of the old stuff getting pulled out, I would put a sponge prefilter on the AC70 just to collect the debris. 

[sumplkrum]

I let it work it's way into the gravel so the plants can eat it. If you don't have many rooted plants I guess bacteria still eats it, but it becomes unsightly in excess.

I don't really vacuum the gravel. I gently swish my hand to move the water near the bottom, then vacuum up whatever loose stuff kicks up.

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You could add a powerhead near the bottom of the tank to add more movement. Make sure the fish have somewhere to rest though. You don't want so much flow that they're just constantly fighting the current.

[Brian]

What Tihshho said.   I agree