Removing bad sand

[GaryP]

I'm still a little mystified over the whole sullfur issue and I plan on doing some reading on it this weekend. Organic waste contains sulfur in the form of protein. Sulfur acts as linkages in protein molecules to give it a functional shape. This sulfur needs to be processed at some point in the waste treatment process. This proteinaceous sulfur is most likely processed by aerobic bacteria and what is not used by them is released into the water as inorganic sulfur compounds such as sulfate. There are anaerobic bacteria called Sufate reducing bacteria (SRBs) that use sulfate like aerobic bacteria use oxygen. The bacteria most commonly encountered in marine systems is Desulfovibrio desulfuricans. The end result of this is the formation of hydrogen sulfide (not sufur dioxide). SRBs are a natural part of all marine and FW sediments. The reulting hydrogen sulfide is often precipitated as an iron salt, iron sulfide. This is the black material that you often see in a DSB when you tear it down.

Additionally, other bacteria may digest proteins and the resulting products may include compounds called mercaptans. They have a similar smell to hydrogen sulfide. Mercaptans are the products that are used to add odor to natural gas, propae, and butane so that leaks are easily detected. My opinion is that these compounds are simply the natural product of bacterial decomposition and do not necessarily indicate that the sand bed is "unhealthy."

I guess the question is what is the fate of organic sulfur in a "healthy" system. As I said earlier, I'll read Shimek and see if I can come up with some better answers. I know how the natural systems work, and I have theories about aquarium systems and am open to new explanations.

Just as there is a nitrogen cycle and phosphate cycle in any environmental system, including aquariums, there is also a sulfur cycle. The nitrogen cycle in an aquarium is similar, but not identical, to that in nature. I feel that is probably the case with the sulfur cycle. I'm not disputing Shimek's claims. I am, however, admitting that I don't understand them from a nutrient cycling, system management, and microbiology standpoint.

BTW, when I worked as a microbiologist, my specialty was sulfate reducing bacteria in industrial water systems, especially oilfield injection systems.

[Thunderkat]

I don't see a problem with your tank, its looks really nice. I see very little problem algae and cyano.

I have lots but it seems to be going away albeit slowly. The things people have recommended to me are increasing flow, use RO water for all your water changes (of course mix it with your sea salt mix), do a 10% water change every two weeks until under control, use activated carbon, and for me pull out the cyano with your hands (I pulled out large handfuls at a time).

[GaryP]

For a Nano I would recommend weekly 10% water changes as SOP.

[greasemonkey]

Thanks for the compliment Thunderkat, I just feel I could be doing alot better for these critters.
For the first 6 mo.s the tank was lit by a cheap light and then I bought the Aqualight. I have replaced the bulbs 2 now thinking it had to be every 6 months. Glad I saved my old bulbs. Also latley I have been doing 2.5 gal changes every week.

[gjuarez]

I now have my explanation on why a sand bed needs to be deep in order to function. Thanks guys