Gravel vaccuuming and bio-filter

[wetmanNY]

I've just had a quick look, with a flashlight, up under the bottom of the only tank I have that's on an open metal stand. As RTR predicts, what's settled to the very bottom and is visible is the finest-textured pale ochre cat-litter silt, speckled with small dark brown bacterial colonies that could be sources of some hydrogen sulfide, which in turn must attract the sulfide-oxidizing bacteria that turn it to sulfate, since all souces of energy attract the bacteria that utilize them-- certainly in undisturbed freshwater microenvironments.

By the time organic particles have broken up and been broken down and have settled deep into low-oxic levels of the substrate, they have been so thoroughly stripped of their nutrients and so thoroughly reworked by detritivores and decomposers, that what remains isn't potentially harmful, just an excellent silty substrate for attracting iron or phosphate. And for anaerobic bacteria.

But if I were disturbing my substrates, all kinds of rich organic goodies would be finding their way down to anoxic levels, there to cause troubles with anaerobic decay.

(I'm completely ignorant of fish-only tanks: even my childhood guppies had Cabomba and Elodea to pick through. So I'm only describing the one kind of fishkeeping I know.)

 

[99RedSi]

Excellent information. Thank you all.

The consensus then is deep vacuuming for non-plant FW tanks and no vacuuming for plant FW tanks.

 

[O-man21]

yes and no........ You may still need to vacuum planted tanks. just around where the root ball is. and yes, you do need to deep clean unplanted tanks once a month usully unless you have messy fish

 

[RTR]

I only have one tank now where I can see the bottom glass from underneath - I do miss those old stands.

I vacuum FO tanks fully every week. that is part of my protcol for the best water quality I can manage. It works for me, YMMV.

Planted tanks I vacumm into the the substrate only at very long intervals when I am breaking up and redoing overgrown clumps of crypts, val etc.. Otherwise I do not go into the substrate at all - but my planted tanks are planted - no substrate visible if viewed from above.

Edit: I forgot to react to Wetman's foci of anaerobic activity under the substrate - those things are harmless in undisturbed substrate as a rule. Gaseous sulides, etc. are unlikely to make to and through the substrate surface - other bacteria will oxidize them in higher oxygen layers. Extensive areas of anaerobic activity are higher risk just from their greater mass - but still relatively safe other than from human intervention.

 

[O-man21]

yea I guess you have a point there.......I thought we meant lightly planted tanks not heavily

 

[Tiger15]

From practice, I do wall to wall substrate vacuuming every couple weeks, sometimes together with replacement of new filter pads, and I have never had any problem but rather prevent problems from occuring. In a cycled tank, I don't believe you can uncycle it by over cleaning unless you follow through with chemical sterilization. There is enough bacteria left on all surfaces that they will quickly repopulate if there is a population deficit.

What you are siphoning out of the substrate is mostly organic matter, dead bacterial cells and heterotrophic bacteria, fungus, protozoas and other microorganism. They feed on organic matter and produce CO2 and ammonia just like fish. Nitrifying bacteria is only a small fraction of the total microbial population and inevitably some will be removed. But the overall effect is a substantial reduction of organic loading, restoration of the substrate pore spaces, lowering demand for but providing better living environment for the nitrifying bacteria.

 

[99RedSi]

Originally posted by Tiger15
From practice, I do wall to wall substrate vacuuming every couple weeks, sometimes together with replacement of new filter pads, and I have never had any problem but rather prevent problems from occuring. In a cycled tank, I don't believe you can uncycle it by over cleaning unless you follow through with chemical sterilization. There is enough bacteria left on all surfaces that they will quickly repopulate if there is a population deficit.

What you are siphoning out of the substrate is mostly organic matter, dead bacterial cells and heterotrophic bacteria, fungus, protozoas and other microorganism. They feed on organic matter and produce CO2 and ammonia just like fish. Nitrifying bacteria is only a small fraction of the total microbial population and inevitably some will be removed. But the overall effect is a substantial reduction of organic loading, restoration of the substrate pore spaces, lowering demand for but providing better living environment for the nitrifying bacteria.

So leaving the substrate untouched (except for cleaning the surface) in a planted tank (medium-heavy) isn't going to harm anything or do any damage down the road?