Air bubbles rising from gravel

[BAT]

In one of my tanks I sometimes notice air bubbles coming up from the gravel.  It’s not a steady stream of bubbles. Just a few here and there. Is it bacteria working in the gravel? Is it a problem?  One time i noticed it right before a nitrate spike.

 

BAT

[HotTunaCartel]

I wish I could give you a straight answer, I get that from time to time after topping my stratum with 2mm gravel.  I haven't seen any change in water chemistry though.  

[JackH]

I’ve had this happen with sand, when I put it in air bubbles got trapped under the sand and every now and then air bubbles rise out of the sand from when I put it in. That’s my theory.

[Guppysnail]

My loose understanding is as bacteria break down organic waste they produce gasses like we exhale carbon dioxide they exhale gas of some type.  Vacuuming regularly reduces this from happening or Malaysian trumpet snails who churn the substrate. Roots of plants growing also reduces this to a point. Some folks never disturb gravel if they do for whatever reason they release tons of nutrients into the water column also causing nitrate spikes. I have heard debates going both ways for is it harmful or not or just how harmful.  I really have no clue about that as I’m a vacuum-er regularly I rarely experience it, but have seen it a few times. 

Edited April 29, 2022 by Guppysnail

[Torrey]

On 1/29/2022 at 5:39 PM, BAT said:

In one of my tanks I sometimes notice air bubbles coming up from the gravel.  It’s not a steady stream of bubbles. Just a few here and there. Is it bacteria working in the gravel? Is it a problem?  One time i noticed it right before a nitrate spike.

 

BAT

How old is the tank, temp, pH GH, KH, nitrites, nitrates, ammonia? How deep is the gravel?

Is there anything under the gravel? (UGF, active substrate, etc?)

Because it can be many things, and without more information there's no way to know for sure.

Newly set up tanks can release oxygen bubbles, and an overly oxygentated water supply can repeat the process after a tank cleaning/refill.

Old tanks with lots of mulm, tanks with fine gravel/sand/soil (especially if they are deep substrate) can develop hydrogen sulfide spots in deeper gravel. The bubbles from that will smell like sulfur when they hit the surface.

Sometimes a UGF filter will have a surge or have the airstone improperly placed, and oxygen bubbles will periodically leak out the gravel.

Decomposing plant matter, or a decomposing snail in the substrate can offgas methane due to the decom.

[Wrencher_Scott]

On 4/28/2022 at 8:24 PM, Torrey said:

How old is the tank, temp, pH GH, KH, nitrites, nitrates, ammonia? How deep is the gravel?

Is there anything under the gravel? (UGF, active substrate, etc?)

Because it can be many things, and without more information there's no way to know for sure.

Newly set up tanks can release oxygen bubbles, and an overly oxygentated water supply can repeat the process after a tank cleaning/refill.

Old tanks with lots of mulm, tanks with fine gravel/sand/soil (especially if they are deep substrate) can develop hydrogen sulfide spots in deeper gravel. The bubbles from that will smell like sulfur when they hit the surface.

Sometimes a UGF filter will have a surge or have the airstone improperly placed, and oxygen bubbles will periodically leak out the gravel.

Decomposing plant matter, or a decomposing snail in the substrate can offgas methane due to the decom.

All this is very interesting. Have you seen any of this happen in any of your tanks?

What exactly can you tell from the temp, pH, KH, nitrates, and ammonia? 

Thanks.

 

[Torrey]

On 4/28/2022 at 9:32 PM, Wrencher_Scott said:

All this is very interesting. Have you seen any of this happen in any of your tanks?

What exactly can you tell from the temp, pH, KH, nitrates, and ammonia? 

Thanks.

 

I have seen all of these, at one point or another. I documented the hydrogen sulfide in my "Walstad Inspired...' journal. I've also had aquariums for almost 5 decades, so I have had plenty of opportunities to learn by screwing up first.

Temperature affects decomposition, so it's an important variable to know. An 82 to 86 F Discus tank with a deep substrate might have hydrogen sulfate bubbles being released (deep substrate) but it would also have a faster rate of decom--> methane off-gassing would be fairly likely, especially with a shallow substrate.

High tannic ==> lower pH metabolizes decom faster (peat bogs are a great example) and don't have the off-gassing at lower temps, but can at higher temps.

GH and KH also affect various chemical interactions in the tank, including plant uptake of various nutrients, which can further influence bubble production (bubbles are gas, and some type of gas is a byproduct of most chemical reactions).