Gravel vaccuuming and bio-filter

[99RedSi]

I was wondering if gravel vacuuming your tank with a syphon/python disrupts or even possibly destroys (if taken too far) the beneficial biological bacteria in the gravel?

Or maybe I'm way off?

[ArkyLady]

From what I've read, the bacteria will be securly attached to the gravel and you shouldn't be able to dislodge enough of it to harm your bio filter.

[FishBait]

Agreed, you will inevitably remove some of your bacteria, but not enough to cause any significant loss. Of course if you are worried about it, you could always do the 1/2 gravel method, where you only siphon half of it at a time.

[99RedSi]

How long does it take to re-establish it after it's been vaccuumed out?

[NJ Devils Fan]

I would imagine about a week or so.

[Hammerman]

Originally posted by ArkyLady
From what I've read, the bacteria will be securly attached to the gravel and you shouldn't be able to dislodge enough of it to harm your bio filter.

Originally posted by FishBait Agreed, you will inevitably remove some of your bacteria, but not enough to cause any significant loss. Of course if you are worried about it, you could always do the 1/2 gravel method, where you only siphon half of it at a time.

I agree with both ArkyLady, and Fishbait... You shouldn't have an issue.

[ewok]

crud mixed in the gravel will disrupt things as much or more than being vacuumed........

[RTR]

Agree w/ewok. Smothering the biofilms with mulm is harder on the bacteria than vacuuming. Consider the case of fluidized bed filters - they are effectively being vacuumed 24/7/365 and function as nitrification devices.

[wetmanNY]

My fears that bacteria were ground off gravel surfaces used to be exaggerated, until calmed by RTR's point about fluidized bed filters. I still think a floc of humus the same size as a grain of gravel offers enormously greater microzones for bacteria.

I prefer to leave the microhabitats of facultative bacteria that can switch between aerobic and anaerobic metabolisms-- and maybe even some obligate anaerobes-- to develop in peace, oxidizing any sulfides to harmless sulfates, creating acidic low-oxygen microzones where the iron in my substrates is ferrous and available to plant roots, maybe even giving me some de-nitrification (my nitrates typically run <10ppm). Besides, my older (5 or 6 year) substrates are probably quite laden with phosphates by now.

I keep reading "algae problems" threads in all the forums that reinforce my impression that algae problems are related to: overwashed "aquarium" gravel with no humus "crud"or silt, substrate disturbance and a snowstorm of flake feed. My tanks have many kinds of algae in them, but not much of any one kind.

Gravel-digging roles are taken up by Melania snails and Botia modesta hunting for them like truffle dogs, since I don't have any big earth-shifting Cichlids.

How would "crud" work its way down into the substrate if the fishkeeper didn't stir it all in, from time to time? What happens to detritus below the surface: doesn't it break down pretty completely, leaving only some dark "humus."

You see, there is a successful different way...

[RTR]

That mulm, at full digestion, is very fine particulate, close to an organic clay. It does not take hobbyist intervention to get it to sift down between the gravel grains. For planted tanks within reason it is great nutrient reservoir. Unfortunately for FO tanks it is the same, and IMHO is more likely to result in algae issues than not. For FO, I'll stick with routinely full-depth vac'd substrates and low nitrate and phosphate water columns. For planted tanks I'll leave it in place, and get low nitrate and phosphate water columns by the action of the plants.

There is one caveat here which we have ignored - if the substrate has been ignored itself for long periods, the nitrifiers (and other aerobes) will have been suffocated on the gravel particles and have migrated into the mulm. Massive cleanup of this after long neglect is likely to affect the bacterial colonies/biofilms.

[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?