Sulfur Based Nitrate Filters

[lduncan]

My nirates are slowly creeping up, despite regular water changes. Does anyone have any experience with sulfur based nitrate filters/reactors. Reef, I know you do, do they work?

Layton

[reef]

they sure work.

here is some info from a german page

If you feed much and you have many fish in your aquarium nitrate will accumulate with the time. If you cannot lower the concentration with water change, trickling filter or living stones you need a nitrate eliminating filter system. If nitrate is more than 20 ppm in the water negative growth of green or blue green algae will occur. Some kinds of fish do not tolerate high amounts of nitrate, too.

Autotrophic de-nitrification has some advantages compared to systems that work with heterotrophic bacteria. With the ADN filter you do not need an organic compound. Theses substances like alcohol, organic acids, sugar, PHB = poly-beta- hydroxy-butyric acid ("Deniballs") etc. may pollute the water. Additional a very strong bacteria growth will occur. These bacteria are polluting the water, too. The handling of heterotrophic filter systems is very complicated or you need an expensive controller (look at Roto-Bioreactor).

The small disadvantage is the long time to start the filter and if you have very rough changings in the nitrate concentrations, the filter will need a little more time to adapt to the new concentration. But in an aquaristic system you will not have difficulties. Like other autotrophic bacteria - nitrifying bacteria - they will work in a coral reef tank without problems. The advantages are much bigger than the disadvantages:

long life time of the filter substrate

low biomass growing - therefore low bacteria pollution of the aquarium water

high flow rates

no additional organic compounds are necessary

easy de aeration

intensive mixing wihin the filter with a good pump - therefore high efficiency

if you wish with Redox control (ORP)

for filter sump or for stand allone

[Dr.Felix]

It is possible to denitrify water without resorting to anaerobic conditions, alternative reduction substrates (sulphur etc) and low molecular weight organics.

use of a fluidised bed containing a proportion of high molecular weight organic compounds to use as the carbon source for the bacteria is possible. I am currently investigating this as a denitrifying method as it does not require anaerobic conditions or low flow. a proprietary mix of standard silica type media for the bed and an amount of carbon compound should allow denitrication as well as full conversion of ammonia throught to nitrate without loss of carbon compounds into the water.

the "algae filter" is also an interesting device for removal of po4 and no3 with consequent reduction of tank bound unsightly algae etc and although it would require more frequent water changes to top up nutrients (or addition of minerals) it is still an excellent way of undesirable nutrient reduction.

[lduncan]

Dr Felix,

some people will go running if you even mention silica based media in a marine environment. Silica is thought to be the limiting factor, in many cases, for diatom growth. So the thought of adding a silica based media may scare some people. I myself believe that diatoms are the "nicest" form of algae, in that they are easily blown off rocks, as opposed to hair algae, and are easily removed by an efficient skimmer, eventally, if there is enough silica available, somthing else with become the limiting factor in their growth, which may be something like nitrates, meaning silica may actually help to keep nitrates low. It is still a highly debated topic.

I have been experimenting lately myself with dosing cane sugar (an aldehyde closely related to alcohols), it is along the same theory as dosing vodka, give the tank enough of the right type of nutrients (carbon based) to kick start a mini bacterial bloom, which hopefully will reduce nitrate.

IT works, very fast too. Started 3 days ago, and already nitrates have dropped from around 9ppm to 6-7ppm. As far as the bacterial bloom was concerned it was not noticeable when looking from the front to back of the tank (2 feet of water) but was noticable when looking down the 6 foot length of the tank, a slight milky colour. The skimmer has been working overtime removing junk. Corals do not seem to be affected so far, all showing their normal polyp extension, and fish seem unaffected.

Apparently this method also removes phosphate, however I have never had any detectable phosphate in the tank, so I can not confirm or deny that. It will be interesting to see how my acros colour up in these reduced nitrate conditions.

Layton

[Pies]

I am not convinced on the merrit of the addition of Vodka, sugar etc reports are sketchy at best. I would say that if you think it works and are happy with the results then good luck. I would point out dozens of featured tanks of RC etc that don't use them and have fantastic coral growth and colour. Something to keep in mind.

There is no doubt that coral colour is affected by Nitrite, Nitrate, amonia and Phosphate. I have never had a reading on Nitrite, Amonia, or Phosphate. But I do suspect they are there. A fludised Rowaphos reactor is a posibility for me.

Nitrates in my tank have crept from undetectable to about 3-5. I have noticed a darkening of my coral that co-insides with this reading. 0 Nitrates are the name of the game for sure. Sulpur denitratifiers work, have few disadvantageds (other than cost & low PH/KH) but one is not on my radar. Reducing the Nitrates is, but I suspect there are better methods (DSB).

Only my thoughts but I am trying for as natural as practically possible. And would be tempted to try a 'eco sysem' reef next time (skimmerless or WAY under skimmed).

Silicates feed the diatom. I have never seen diatom blow of anything, it is a golden 'rash' that is easily wiped off but no amount of current will remove it, maybee you are confused with Cyno?

Pieman