Remote DSB in sump and Hydrogen Sulfide

[JRR1285]

I started up my tank back in October '12. After adding some live stock and noticing nitrates creeping up, I then added a sump with a skimmer and refugium. The refugium portion has about 4-5 inches of sand in it with rocks on top as well as some chaeto that I will periodically trim down. I also added chemipure elite to the sump and in a matter of a week I had 0 nitrates.

I removed the chemipure probably 6 months ago, nitrates are still undetectable. Phosphate was creeping up so I added a phosban reactor in May/June of this year. That helped with the phosphates. I recently took the reactor offline so now I have some measurable phosphates. I'll come back with an actual number once I test again in the next day or so.

Last week I was doing some sump maintenance and was rearranging the rocks sitting on the sand bed. I removed the rocks and vacuumed up the remaining water and I got a slight odor. I am concerned I am producing Hydrogen Sulfide. Is it bad to have rocks on top of my sand bed? Am I creating those anoxic zones I have been reading about when I look up DSB's? I didn't see any blackness on the bottom of the rocks and the sand underneath looked new like the day I put it in. Once the rocks were out it didn't smell at all. I'm thinking maybe there was some gas build up between the rock and the sand bed. I am considering putting the rocks on some light diffuser to allow flow between the rocks and the sand.

Sorry for the long winded post. Just trying to gather up some info to add to everything I've been reading up to this point.

 

[power boat jim]

The odor of H2S is unmistkeable. If you got a whiff of it when you removerd the rocks then it is likely that there was some buildup. I dont know what you might find on the bottom of the sand bed. Wouldnt the diffuser provide a ton of tiny pockets for detritus to get caught up in? I dont know just something to consider before you do it.

 

[JRR1285]

I see little if any detritus buildup in my sump due to using a filter sock and feeding light.

I also don't have any critters down there that could disturb the sand bed. My tank is doing well enough that l I am hesitant to do much about the setup in the sump. It's just been on my mind lately and I am looking for opinions on it.

Thanks for your response and I am worried about what the bottom of the sand bed looks like and what nasty surprise I may find if I stir it up.