Bad smell in Refugium

[Guy]

I have a 6 inch sandbed (Southdown playsand) in one of my refugiums ( ~ 40 gallons of water + 150 pounds sand). It has been set up for about 6 months. I have a lot of small pieces or rock placed on top of the sand and it is very dense with caulerpa (for nutrient export). Water flow through the refugium is about 50 gallons/hour.

This morning I pulled out a rock to remove the caulerpa and got a whiff of a bad odor. I took a better smell of the rock and it is definately a hydrogen sulfide odor.

Is this a disaster waiting to happen? Should I take the refugium off-line? What went wrong? Can the problem be reversed?


Guy

[rshimek]

Hi Guy,

Originally posted by Guy

Is this a disaster waiting to happen?
No.
Should I take the refugium off-line?
No
What went wrong?
Nothing

Can the problem be reversed?

What problem? What you are smelling is normal for the conditions.

A lot of small rocks and dense algal growth on top of a sand bed reduces water (and hence, oxygen) flow to the sand bed. This lack of oxygen kills a lot of the sand bed critters and causes the anaeroblic layer to rise to the surface area.

You probably haven't noticed any effect of this in the main tank. Nor will you... :D

I would suggest, 1) harvest the Caulerpa more frequently, 2) remove the small rocks; you want to expose sand bed surface to water movement, and 3) get a detritivore kit for the sand.The only organisms the anaerobic conditions have effected were the sand bed fauna in the refugium. Once the water flow over the substrate is restored and the sand repopulated with critters, the anaerobic layer will sink down out of concern.

[Guy]

Whew! Thank you Ron!!!

I'll take your advice, I just panicked a bit there, thank you for the slap in the face to bring me back to consiousness :) I was wondering why the worm population had decreased......

I just traded the caulerpa for a nice frogspawn. So nice for something I was going to throw out :D

You are doing a great service for the hobby and it is greatly appreciated by me.

[rshimek]

Hi Guy,

Glad to have been able to help! ;)