Nitrate Removal

[Paul227]

hello Reefers

i have been getting slow increase in nitrates the last few days (only a relitivly new tank) and therefor are looking at means to reducing or control these nitrates (preferably without vodka dosing).

I was looking at a few different options (my tanks is only 200L). I have read somwehere along the lines that the nitrate media can actually negativly affect your calcium and alkalinity/Ph levels and therefore should be run through a buffer or another reactor with other media before geoing to the tank.. is this really as much of an issue as people say or is it exagerated?

If it isnt super important i was looking at something cheap, simple and easy like this...
http://www.ebay.com.au/itm/BRAND-NE...939756?pt=AU_Pet_Supplies&hash=item2c5e512eec

however if you think it is important to buffer the PH i was thinking of doing a DIY job, based on this...
http://www.vellemanprojects.com/be/en/prod...view/?id=366732
but mabye only two chambers ~ two chambers, both with a nozzle on the top and sealed off at the bottom, but also at the bottom connected with a smaller piece of PVC, water through the top, down through the nitrate media, then into the second chamber where it can pass through either another media or fresh coral rubble towards the tpp, and then out into the aquarium..

whats everyones take on this situation? cheers guys.

Paul

 

[HighlandReefer]

Nitrate in the Reef Aquarium
http://www.advancedaquarist.com/issues/august2003/chem.htm

From Randy's article:

"7. Use A Sulfur Denitrator.

In these systems, bacteria use elemental sulfur and produce N2 from it and nitrate according the following equation (or something similar):

2 H2O + 5 S + 6 NO3- → 3 N2 + 5 SO42- + 4 H+

It has also been suggested to pass the effluent of such a reactor through a bed of aragonite to use the acid (H+) produced to dissolve the calcium carbonate, and thereby provide calcium and alkalinity to the aquarium.

While that is a fine idea, it doesn't add much calcium and alkalinity to most aquaria.

To estimate the magnitude of the effect, we start with a liberal estimate of how much nitrate might be removed. Say 10 ppm of nitrate per week.

10 ppm nitrate = 0.16 mmole/L of nitrate

Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce

0.107 mmoles/L of H+ per week

How much calcium this could produce?

Assume that it takes one proton to dissolve one calcium carbonate:

CaCO3 + H+ → Ca2+ + HCO3-

Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of 0.107 mmoles of Ca2+ per week since calcium weighs 40 mg/mmol, that's 4.3 ppm Ca2+ per week.

For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day. Consequently, this method may not be especially useful for maintaining calcium and alkalinity levels. On the other hand, the acid produced will have a long term lowering effect on the alkalinity, so if you use it, watch the alkalinity.

As to its actual ability to reduce nitrate, I cannot say for sure. I expect that it can be made to work, but the only aquarist that I have spoken to that uses one has had considerable difficulty with it."

 

[bertoni]

I agree that the calcium issue isn't important. I'd likely go with a ready-made product, but a DIY project might be fun.