Everyone survived the switch from gravel to sand and wow what a behavior change

[Fishmanic]

To prevent gasses from forming under the sand, I often stir up the sand and then let it settle back down. Just turn off your filter till it settles. I just skim the surface with the python wc device and not much get sucked up so much it ends up in the sink. I use pool filter sand. It is white but required very little rinsing before putting it into the tank. I have lot of plants, driftwood, and rocks so substrate is not totally white...I guess most fish prefer darker substrates. This works for me in 2 or my tanks...one of which has cories.

 

[FishGuest5123]

That will be H2S. Its important not to have the sand deeper than 1 - 2". Deeper than that and you will get anaerobic de-nitrification and hydrogen sulphide, think deep sand beds in marine tanks. I only ever pick up dead leaves etc. I do occasionally move it away from the glass to clean off the algae that grows beneath the surface where the light gets to it.

When I first switched to sand I used to vacuum it then give it a good stir at every water change (with the pump turned off) because I was terrified of getting pockets of the foul smelling stuff (which kills fish BTW). Chopsticks are useful tools for this. When I realised this wasn't happening I just left it alone with the same results as @AbbeysDad. In fact it was he who recommended that and he was right.

I stir it for that very reason. Why do you not want to stir it? I have less than an inch in mine. I read it could bubble up and release the gas on its own if you don’t stir it. Now I’m confused.

 

[Fishmanic]

Byron is saying if its not too deep there is no need to stir it up. Mine is a bit deeper than yours so I do stir it up. Just turn filter off if u do stir it up occasionally.

 

[FishGuest5123]

Why does mine smell like sulphur? I stir it but never turned the filter off. Is that to keep it from sucking it up?

 

[Fishmanic]

Yes, prevents sand from getting in the filter so it wont bind . Your sand must be over a couple of inches deep so sulfur gas is being formed .. Stirring it up occasionally releases the gas so it doesn’t continue building up and potentially harming the fush.

 

[FishGuest5123]

I cleaned yesterday and stir it as I vacuumed. Just vacuumed it again. Just started noticing the smell about a month ago. Sand has been in about a year. I use to just run a knife through it. Now I’m really stirring it.

 

[AbbeysDad]

I think stirring sand may be very bad...here's why...
The particle size of sand is so small that organic matter can't get down under to decompose and produce foul gases/smells. But if/when you stir, you're mixing any uneaten food and/or waste on the surface down under into the sand where it can be subject to anaerobic decomposition. Like I posted, my 60g has had pool filter sand for 8 or 10 years now and I just leave it alone! <see photo above>

 

[FishGuest5123]

I am so confused! Been reading and everything says to stir. Spoke with fish buddy who does the aquatic research and she says I need to stir more often. Been reading all night. I am a natural born worrier.

 

[Colin_T]

If you have sand in the tank you need to be careful about anaerobic pockets forming under it. This normally occurs in deep sand more than a couple of inches thick. If the sand is shallow (1/2 inch thick), it is unlikely to get anaerobic pockets. Anaerobic pockets turn the sand black and it usually smells bad.

If you gravel clean the sand you will remove any uneaten food and fish waste from it and this helps prevent organic matter getting into the sand and causing anaerobic areas.

Anaerobic simply means lacking oxygen.

 

[FishGuest5123]

Well, my sand is black so that doesn’t help. I was just thinking though...I have lots of MTS in that tank. Shouldn’t they be enough to prevent anaerobic pockets from forming? The sand smells like Prime.

 

[FishGuest5123]

I found this old thread from our forum. Abbey’sDad is right according to this:

Post by Bignose, Retired Moderator
I've posted this a few times over the years, so here it is again:

The main concern people have about sand would be anaerobic bacteria build-up. Anaerobic meaning without air, though more accurately, without oxygen. If you didn't know, the ammonia and nitrite reducing bacteria require oxygen to work (to convert ammonia to nitrite and to convert nitrite to nitrate).

Anywho, under anaerobic conditions, bacteria start to get their energy from other sources, like reducing sulfur instead of oxygen. And a by-product of that is hydrogen sulfide, yes, one of the deadliest compounds in nature.

But, there is relief. In water, as soon as hydrogen sulfide comes into contact with any oxygen, it will become harmless. So, even if there is a pocket, and even if you accidentally stir it up, it will become harmless as soon as it hits your well-oxygenated water. And you know your water is well-oxygenated since your fish are living in it, and they need oxygen. This is the stinky smell you got, sulfurs, but you most likely smelled sulfur oxides, not hydrogen sulfide. Like I said, hydrogen sulfide decomposes very quickly in the presence of oxygen while in aqueous solution.

So, there really isn't anything down there to worry about, so my recommendation is to not stir it at all. Just vacuum the top of the sand to get the uneaten food off the top. If uneaten food on the top is a constant problem, you probably should be feeding less, maybe a lot less. If it really bothers you, maybe decrease the thickness of your sand layer.

p.s. Another source of energy anaerobic bacteria may use is actually to convert nitrates to nitrogen gas. This is what living rock and living sand does for some marine tank setups.


Here is another quote from another post of mine:

Diana Walstad in her book Ecology of the Planted Aquarium actually talks about the beneficial aspects of having anaerobic conditions under the substrate near the plant roots. She has around several inches of soil as the substrates in her tanks. The anaerobic bacteria will use most anything for an energy source, reducing nitrates is just one of them. The bacteria can also reduce iron, sulfur, manganese, and so on. The great thing for plants is that these reduced forms are much more easily taken up, so anaerobic conditions help the plants get their micronutrients.

So now is my sand contaminated because I stirred it? Do I need to remove it or will it break down? Suggestions?

 

[seangee]

foul smelling stuff (which kills fish BTW)

Like I said, hydrogen sulfide decomposes very quickly in the presence of oxygen while in aqueous solution.

I posted the short version . The danger to fish is the pH crash that accompanies this conversion. Tiny pockets are fine when you stir regularly. Disturb a big one and your fish are at serious risk. The easy option is don't have deep sand.

In 2 of my 3 tanks the sand does get stirred daily - by the MTS (assisted by the corys in one of these). The 3rd only has 1" of sand and a raging flow. So I am going to continue not touching the sand

 

[FishGuest5123]

I have shallow sand and MTS. Hopefully that’s enough.

 

[AbbeysDad]

I have shallow sand and MTS. Hopefully that’s enough.

You should be fine, and no need to stir. Here's the thing...First there are of course many types of sand of various particulate size. Some very fine sands pack tightly, while coarser sands do not. Less of an issue in shallow substrates than in deeper ones. In deeper sand substrates near the surface we have the aerobic region with lots of oxygen. Then a bit deeper is the anoxic region where there is little O2, but still some. Then deeper still is the anaerobic region where there is no oxygen. So these regions are somewhat relative to the grain size of the sand and the depth. Typically in the 1" depth or so, nearly all sands will be aerobic. Any deeper we begin to explore the other regions, again relative to grain size.

I'm using pool filter sand in my 60g at about a 3-4" depth. Unlike finer sands, obviously the grain size of pool filter sand is large enough to allow water to flow through it. Other sands vary in grain size. Many hobbyists use play sand. This can be great, especially if well washed to remove fines, but I have seen some very fine play sand. Deeper depths of finer sands will result in the anoxic and anaerobic layers at shallower levels.

Now all of this is fairly unimportant with one possible exception. As I previously mentioned, the particle size of sand is so small that unlike most gravel and pebbles, uneaten food and waste does not get down under to decompose in anoxic or anaerobic regions - hence there is no production of unwanted gases (like hydrogen sulfide) and resulting odors...unless there some condition (like stirring in deep sand) that pushes waste down under.

 

[FishGuest5123]

You should be fine, and no need to stir. Here's the thing...First there are of course many types of sand of various particulate size. Some very fine sands pack tightly, while coarser sands do not. Less of an issue in shallow substrates than in deeper ones. In deeper sand substrates near the surface we have the aerobic region with lots of oxygen. Then a bit deeper is the anoxic region where there is little O2, but still some. Then deeper still is the anaerobic region where there is no oxygen. So these regions are somewhat relative to the grain size of the sand and the depth. Typically in the 1" depth or so, nearly all sands will be aerobic. Any deeper we begin to explore the other regions, again relative to grain size.

I'm using pool filter sand in my 60g at about a 3-4" depth. Unlike finer sands, obviously the grain size of pool filter sand is large enough to allow water to flow through it. Other sands vary in grain size. Many hobbyists use play sand. This can be great, especially if well washed to remove fines, but I have seen some very fine play sand. Deeper depths of finer sands will result in the anoxic and anaerobic layers at shallower levels.

Now all of this is fairly unimportant with one possible exception. As I previously mentioned, the particle size of sand is so small that unlike most gravel and pebbles, uneaten food and waste does not get down under to decompose in anoxic or anaerobic regions - hence there is no production of unwanted gases (like hydrogen sulfide) and resulting odors...unless there some condition (like stirring in deep sand) that pushes waste down under.

Thanks so much. Just vac top for now on.