Questions about vacuuming the sandbed

[homer1475]

So last night while I was doing my normal WC routine, which includes vacuuming the sandbed, I got to thinking, "I wonder if I'm vacuuming out all the microfauna I'm trying to build up for an eventual mandarin and leopard wrasse?" I don't see a ton of microfauna in my WC bucket after vacuuming the sandbed, but I do see some. I was attributing the small amount to my tank being newish at only 3 months old and not having a ton of microfauna to begin with.

So basically the question is:

Are we sucking up all the microfauna when vacuuming the sandbed that we are trying to grow out to support fish that eat said microfauna?

[downbeach]

If this is an oolitic DSB, it would be best to not disturb it, and I would let the microfauna do their job. But, I would make sure there was enough of these critters, by adding both this and this. I would also keep some Cerith, Nassarius Vibrex snails, and a Conch to keep the uppermost layer loose.

[homer1475]

Naa no DSB, most newbies now a days have no idea what a DSB is or what its purpose is. I also know that a DSB is better left untouched.

I'm strictly speaking of a 1 to 2" regular reef sand sandbed, which is what most do now.

[C.Eymann]

How deep is your sand bed? I generally recommend people to not disturb the deeper layers as it could lead to releasing hydrogen sulfide into the tank, as well as disruption of hypoxic bacteria causing it to die off.

Personally. I'm a supporter of regular light stirring as opposed to vacuuming also likes of detritus eating critters like nassarius snail and maybe a sand sifting star if you have a large enough tank / sand bed.

[CStrickland]

I think it would be impossible to remove all your microfauna even if you tried.

I notice that in my tank, when I get lazy with cleaning and little piles of detritus accumulate in the sump and at the bottom of the overflow, they get covered with pods and bristleworms pretty quickly. When I clear out those accumulations, I don't see those pods, but also my nitrates drop a few ppm. So there is tension between keeping the water quality I want for my corals and the dirt that pods require for a large population.

I think the same thing happens under the sand where we can't see it. When I vacuum I am removing some of the small critters, many are too small to see, but mostly I am getting rid of their food before it decays into the water. Basically, it's not so much about physically removing them before they can make a large population, it's more about creating an enviro that doesn't support a large population.

I think the small critters can bloom very quickly in the right conditions. The best example I've seen of that is when I qt'd my anthias. I did it when I upgraded to my new tank. I took almost all the rocks and sand out of the old tank, as well as my micro-fauna-assassin wrasse, and put on an auto feeder to fatten up the new fish. So the tank became a little sand that had been vacuumed every week for a year, and a few rocks, but no predators and plenty of leftover food. Within 2 weeks the tank was crawling with all kinds of spaghetti worms, pods, bristles, etc. So I think they are always there and just waiting for an opportunity.

[NS Mike D]

I limit vacuuming my sand bed to just the surface, usually just to remove cyano. I will on occasion disturb the sand up against the front glass above the black trim to remove the algae - but that is only for aesthetic reasons. The top half of my sand bed is fine sand, so I trust my clean up crew to maintain the sand bed.

It may be different for courser sand beds where particles can make their way deeper into the bed. If that was the case, I would be include to limit the cleaning to small sections at a time to give the microfauna a change to replenish between wc/vacuuming.


As for not knowing what a DSB is, the short story is that below 2" (some think deeper), oxygen does not penetrate so that anaerobic bacteria work on ammonia converting it directly to nitrogen. The top level has aerobic bacteria that converts to nitrates/nitrites. If you disturb the sand bed, the bacteria will die off - anaerobic being exposed to oxygen, and aerobic being denied oxygen - producing hydrogen sulfide.

[C.Eymann]

Originally Posted by NS Mike D

I limit vacuuming my sand bed to just the surface, usually just to remove cyano. I will on occasion disturb the sand up against the front glass above the black trim to remove the algae - but that is only for aesthetic reasons. The top half of my sand bed is fine sand, so I trust my clean up crew to maintain the sand bed.

It may be different for courser sand beds where particles can make their way deeper into the bed. If that was the case, I would be include to limit the cleaning to small sections at a time to give the microfauna a change to replenish between wc/vacuuming.


As for not knowing what a DSB is, the short story is that below 2" (some think deeper), oxygen does not penetrate so that anaerobic bacteria work on ammonia converting it directly to nitrogen. The top level has aerobic bacteria that converts to nitrates/nitrites. If you disturb the sand bed, the bacteria will die off - anaerobic being exposed to oxygen, and aerobic being denied oxygen - producing hydrogen sulfide.

Top layer convert waste ammonia/ nitirite into nitrate, deep layers turn nitrate into nitrogenous gases, which is why you typically see the little "bubbles" up against the glass in the sand.

[CStrickland]

Originally Posted by NS Mike D

I As for not knowing what a DSB is, the short story is that below 2" (some think deeper), oxygen does not penetrate so that anaerobic bacteria work on ammonia converting it directly to nitrogen. The top level has aerobic bacteria that converts to nitrates/nitrites. If you disturb the sand bed, the bacteria will die off - anaerobic being exposed to oxygen, and aerobic being denied oxygen - producing hydrogen sulfide.

Originally Posted by C.Eymann

Top layer convert waste ammonia/ nitirite into nitrate, deep layers turn nitrate into nitrogenous gases, which is why you typically see the little "bubbles" up against the glass in the sand.

You're both a little right. You don't want to think of nitrogen processing as a single bacteria that only functions one way. There are several paths that nitrogen can take around, and out of, our tanks. The majority of ammonia conversion is performed by bacteria that can switch between using free oxygen and nitrates. Nitrate is NO3, without oxygen they can take an O leaving NO2 - nitrogen dioxide gas. Because they can switch, they are called facultative; bacteria that have only one option are obligate. The facultative denitrifiers can live in deep sand, rock crevices, or right on the glass of the tank. They also form little clumps where they are feeding each other with the top guys using oxygen and the bottom ones nitrates.

There may be some denitrification by obligate bacteria (can't switch, or live in oxygen rich water) like anammox pathways and such. These would die if you stirred the sand I guess. But it's not the whole story.

In any case, it is very common to disturb the 1"-2" sand bed that OP is asking about. Homer didn't say they don't understand dsb, they said that it's not the focus of their inquiry because most newbs don't even know what it is. Like, dsb is irrelevant.

[desjardini]

Originally Posted by homer1475

So last night while I was doing my normal WC routine, which includes vacuuming the sandbed, I got to thinking, "I wonder if I'm vacuuming out all the microfauna I'm trying to build up for an eventual mandarin and leopard wrasse?" I don't see a ton of microfauna in my WC bucket after vacuuming the sandbed, but I do see some. I was attributing the small amount to my tank being newish at only 3 months old and not having a ton of microfauna to begin with.

So basically the question is:

Are we sucking up all the microfauna when vacuuming the sandbed that we are trying to grow out to support fish that eat said microfauna?

Probably not all of the micro fauna, but over time you will definitely make a significant dent in the population. This is why I prefer to use a small power head and stir up my SSB on occasion as opposed to using a vacuum. It's amazing what can accumulate under the rocks sometimes, a place a vacuum can't get to. When all is said and done though quite of bit of the detritus is either removed via a siphon or a filter sock, leaving the pods, worms etc untouched. I know I'm not going to get all of that muck out, but after almost 9 years so far so good.