hydrogen sulfide in refugium

[GSnake]

today i noticed a fog in the lower part of my fuge while i was harvesting some macroalgae. at first i thought it was kalk settlement, but it wasnt.

the smell told me another story. after reading a few posts about anoxic zones and hydrogen sulfide in your refugium, I have just conferred that it is better to not have this smell at all, cause it can lead to a bigger potential problems; so the best course of action would be to prevent it and clean the fuge once in a while.

I wanted to leave the fuge be, so i have for like almost 12 months and this is the result. the sediment on the bottom is dark, not pitch black.

how do you prevent nuking the refugium population when you clean? i guess its unavoidable now

 

[GSnake]

The fog reappeared after turkey basting some out this morning. About to do a wc in refugium

 

[Spare time]

Sounds like you have some seriously low flow if that is truly an anoxic zone (which seems strange). I'd just pump the water out down there and turn the flow up.

 

[HuduVudu]

It isn't the hydrogen sulfide that is the killer it is the rapid oxydation of what was being otherwise anaerobically reduced that is the problem. Areas like this are usually very high in nutrients and when the oxygen hits that then you have a real problem.

Just be aware when you are dealing with this.

 

[moz71]

How deep is your water in that fuge? It looks deep probable creating no flow down there. Looking at you pic it look it is higher than the spill over indicating very deep unless I am seeing it wrong. If it is the water is probably flowing across surface and creating a dead zone

 

[GSnake]

it is a dead zone, most likely - due to my huge amount of chaeto across the top . the bottom is rubble and little bits of dead chaeto. it doesnt seem like much flow goes down from the skimmer spill over, just across to the next section. (the skimmer spill over is 5.5 inches deep. water is usually 8.5 inches deep though)

i did a whole WC on that middle section and cleared out a good ton a gunk and tiny chaeto bits. it kept clogging the tube so ill use a net first next time. anyways, some rubble has black areas on it now, which is indicative of a hydro sulifide deposit right?. can i still use these rubble or are they best removed now and dried. maybe i can reuse them later?

 

[HuduVudu]

it is a dead zone, most likely - due to my huge amount of chaeto across the top . the bottom is rubble and little bits of dead chaeto. it doesnt seem like much flow goes down from the skimmer spill over, just across to the next section. (the skimmer spill over is 5.5 inches deep. water is usually 8.5 inches deep though)

i did a whole WC on that middle section and cleared out a good ton a gunk and tiny chaeto bits. it kept clogging the tube so ill use a net first next time. anyways, some rubble has black areas on it now, which is indicative of a hydro sulifide deposit right?. can i still use these rubble or are they best removed now and dried. maybe i can reuse them later?

Hydrogen sulfide is not dangerous to your creatures at this level. You can re-use to your heart's content.

To help understand, in the oil fields the workers wear indicators that show if dangerous levels of hydrogen sulfide are present. The reason that they do this is because if you can smell it it you're safe, but if you can't your dead.

 

[moz71]

Hydrogen sulfide is not dangerous to your creatures at this level. You can re-use to your heart's content.

To help understand, in the oil fields the workers wear indicators that show if dangerous levels of hydrogen sulfide are present. The reason that they do this is because if you can smell it it you're safe, but if you can't your dead.

So why would you want to keep a dead zone anyway? Curious, any benefit? I can only think of negatives. Smell, water chemistry balance etc. is there a positive?

 

[Spare time]

You might benefit from dosing iron to help mitigate hydrogen sulfide

 

[HuduVudu]

So why would you want to keep a dead zone anyway? Curious, any benefit? I can only think of negatives. Smell, water chemistry balance etc. is there a positive?

Nitrate reduction is the biggest. Calcium, Carbonate/BiCarbonate and trace element addition. Dead zones are also a very important part of the biodiversity of your tank.

One note though on them is this, they need to stay dead. They don't process nutrients quickly and if they are disturbed and go aerobic they can crash your tank.

Plenums, reverse undergravels, deep sand beds and sulfur denitrators are all forms of denitrifiers that use anaerobic decomposition to do their work.

 

[GSnake]

I would have liked to keep my dead zone but due to it's smell I had to let it go. Can't have the room the tank is in smelling like gas. I didn't think DSBs smell like this either ( my original refugium plan) but a bare bottom definitely can.

 

[Randy Holmes-Farley Verified Community Expert]

Hydrogen sulfide is quite toxic to some organisms and should not be ignored. 50 ppb will kill some marine organisms. There's no reason to think you can gauge the water concentration in seawater by smell of the air nearby.

Hydrogen Sulfide and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com