Will anaerobic pockets form in loose thin layer of substrate?

[philipraposo1982]

I just removed all my substrate to add some new stuff. only did a very thin layer about .5"

I had a fine sand mix before and it was forming pockets quickly and I didn't want to have to worry about it. The new stuff in a much larger grain gravel type substrate. I am pretty sure it won't be an issue now but I just wanted to hear some other opinions.

Thanks.

 

[philipraposo1982]

Here is some photos of it now for reference

 

[Yuki Rihwa]

Here is some photos of it now for reference

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View attachment 1233046

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The answer is No
When you do WC you will vacuum the gravel for waste that stuck between gravel, so you will eventually stir up all your substrate

 

[philipraposo1982]

I guess I should buy a gravel vac, I never used one previously because the sand I used before was super lightweight and would just get all sucked up.

Before that I had a planted tank and didn't need to vac the substrate.

I guess no matter how thin and coarse the substrate is you still gotta vacuum it right?

 

[viejafish]

You are doing the right thing. Unless you want to grow plants, a thin substrate barely enough to cover the bottom is adequate. Aerobic BB live only in the top 1/2 inch and any thicker substrate will only create anaerobic pockets. Having a thin substrate is better than bare bottom because it makes the fish feel safer, and increases the total surface area for BB many times. I prefer gravel size around 1 mm, large enough to hide detritus which I can vac out in WC, yet not too small to be sucked out.

 

[J. H.]

The bigger your grain size, the deeper you can go before you need to worry. Look up DSB arguments for saltwater. Saltwater i worse as it holds less oxygen, but the idea is the same and they do serious testing and have actual safe deoth numbers for different grain sizes

 

[philipraposo1982]

Good to know, thanks everyone.

 

[SK13]

With a thin layer of bigger grain-size gravel, I do not think air pockets will be an issue.

 

[philipraposo1982]

Thanks for your input.

Either way, with the sand fully out of the equation now, I can easily move and clean the substrate with no issues.

It's just thick enough to not have the glass bottom show. I am thinking of using a turkey baster during water changes to get all the mulm up and into the water column. Should be easy enough.

 

[J. H.]

You may have some issues with your fish digging down too the glass and leaving you bare spots, even with gravel. I had this happen with 1" of gravel in a goldfish tank.