Water Stagnation

[Clownfish_Boy]

Just found out that the artificial reef in my fish-only tank is hollow on the inside and since there is next to no flow, that water in there has become somewhat stagnant (I can smell the odor of Hydrogen Sulfide at the surface of the water). So I will have to either do something to increase the water circulation, or replace the artificial reef itself. So I am wondering, will the stagnant water harm fish ? And I am also wondering if I need to replace all the water in the tank; or will oxygenation will restore the water to normal ? Ammonia and Nitrite are zero, and the fish seem to be doing just fine and not stressed.

 

[HuduVudu]

Just found out that the artificial reef in my fish-only tank is hollow on the inside and since there is next to no flow, that water in there has become somewhat stagnant (I can smell the odor of Hydrogen Sulfide at the surface of the water). So I will have to either do something to increase the water circulation, or replace the artificial reef itself. So I am wondering, will the stagnant water harm fish ? And I am also wondering if I need to replace all the water in the tank; or will oxygenation will restore the water to normal ? Ammonia and Nitrite are zero, and the fish seem to be doing just fine and not stressed.

You should remove it. Try not to let any of the water in it out. Do a water change after you have completed the process. If you think the water will come out then try to ensure that that water doesn't hit the tank. Maybe a bucket or something. If it is really difficult then remove your livestock first for safety.

Problem is that if there are organics in the dead space (and that is very likely) you will release that into your tank. When the aerobic bacteria hit the big organic load they will promptly pull the oxygen down and this will be a major cascading event that won't end well.

 

[mike550]

+1 to remove it.

if you can plug the holes with your hand or something to keep most of the water in the piece that would be good.

For sure consider making some water changes over next few days / weeks. Hopefully that’s the source of the smell.