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View Full Version : What's the deal with nitrates?


rpritch
06/18/2013, 09:37 PM
So I know it is a simple question. Everyone is fighting to keep their nitrates as low as possible.

Let me, however, ask this: what is the absolute max for a reef tank? I know for SPS I need to keep them low, but just how low? I also have a clam and macroaglae. Doesn't this suggest that some levels of nitrate would be acceptable?

Personally, my issue is that I have a small 14 gallon biocube. It has a hefty bioload as well. I am consistently fighting my nitrates, but I'm not sure how low is low enough to say that I've won the battle.

Thoughts?

bnumair
06/19/2013, 12:38 AM
under 20 ppm will be fine for reef. ideal is 5ppm

Timfish
06/19/2013, 07:38 AM
I do not test for nitrates but a common reason I have suspect people so often are advised to keep nitrates low is typically with measurable amounts, as in 10, 20, or higher ppm or mg/l, is indicative of an aquarist that is not doing thier maintenance (but not neccessarally so). Corals and fish can tolerate surprisingly high levels of nitrates. One down side though is high nitrates can cause accelerated coral growth making for a weaker skeleton(1) While Delbeek and Sprung point out the DISSOLVED nitrate (NO3-N) levels of natural seawater off Waikiki Aquarium measure 8 ppb (.008 mg/l) they recommend for reef aquaria nitrate levels should be less than 1 ppm nitrate-nitrogen "ideally but need not be maintained so low"(1). Keep in mind if you are using a test kit that is measuring nitrate ion and not nitrate-nitrogen your reading is about 4.4x higher or divide by 4.4 to convert nitrate ion readings to nitrate-nitrogen.

Phosphates and nitrogen (as ammonium and/or nitrites and/or nitrates) is essential and are limiting nutrients for plants and algae which includes the symbiotic dinoflagellates corals use. Too low and the plant or algae dies. This may not neccesarily kill the coral as they are capable of living without their symbionts. The mistake should not be made that reef systems in the wild are low nutrient systems, here's an interesting quote by Charles Delbeek "When I see the colors of some of these low nutrient tanks I can't help but be reminded of bleached coral reefs . . . Our crystal clear aquaria do not come close to the nutrient loads that swirl around natural reefs"(2). This was echoed by Dr. Gerald Heslinga, ipsf.com, in a conversation with Patrick Castille, aquacultureranch.com, I overheard at NextWave 2011 in Dallas.


1 Delbeek and Sprung "The Reef Aquarium" Vol III pg 175 & 176
2 Coral Nov/Dec 2010 pg 127

DavidinGA
06/19/2013, 08:01 AM
Yeah you don't want your tank to be too "clean".

glennf
06/19/2013, 08:17 AM
ik keep it at about 1-5 it depends on what corals and colors i desire.

rossv
06/19/2013, 08:44 AM
If you need to raise it a bit, what do you do?

SVTour
06/19/2013, 09:12 AM
I'm lost :confused:

I've had this battle for years on end (nitrates in the 5 to 10 range...phosphates around .03). I ended up getting a reactor for nitrates and a reactor for phosphates to get these to 0...and now that's bad?

DavidinGA
06/19/2013, 10:01 AM
I'm lost :confused:

I've had this battle for years on end (nitrates in the 5 to 10 range...phosphates around .03). I ended up getting a reactor for nitrates and a reactor for phosphates to get these to 0...and now that's bad?

It can be depending on what your housing...

Donkeykong
06/19/2013, 11:27 AM
I'm lost :confused:

I've had this battle for years on end (nitrates in the 5 to 10 range...phosphates around .03). I ended up getting a reactor for nitrates and a reactor for phosphates to get these to 0...and now that's bad?

Softies and LPS's actually do a bit better in a little "dirtier" tank, as they seem to absorb the excess nutrients in the tank. But if you are looking for the jaw dropping colors in your sps's you are going to have to get the water pristine. So as mentioned above, where you are aiming is really dependent on what you plan on keeping.

Timfish
06/19/2013, 01:45 PM
I'm lost :confused:

I've had this battle for years on end (nitrates in the 5 to 10 range...phosphates around .03). I ended up getting a reactor for nitrates and a reactor for phosphates to get these to 0...and now that's bad?

Are you saying 0 as in 0 mg/l (ppm) or 0 as in 0 ug/l (micrograms, mcg or ppb)? Because 0 ug/l (micrograms, mcg or ppb) is most certainly too low. (As you can see semantics can cause some confusion here.) I stopped worrying about nitrates a very long time ago and I don't worry to much about phosphates but they should be kept between .03 and .1 mg/l. What seems to be overlooked in this emphasis on reduced nutrients is both nitrates and phosphates are limiting nutrients for algae and current methods can reduce them to levels that are unhealthy for corals. If you don't subscribe to Coral I would encourage you too and Dr Shimek has an excellent article on anorexic reefs in 2010 Nov/Dec issue. Some other articles you might be interested in are:

http://jeb.biologists.org/content/214/16/2749.full High phosphate uptake in Stylophora pistillata

http://www.mendeley.com/catalog/nitrate-uptake-scleractinian-coral-stylophora-pistillata/

http://www.ingentaconnect.com/content/umrsmas/bullmar/1979/00000029/00000004/art00011 Ammonium uptake by Madracis mirabilus

Also I would point out that too often corals get lumped together under labels that simply do not have any meaning regarding their husbandry. For example Pocillopora damicornis and P. ligulata would both be labeled as "SPS" but P. damicornis is found in mangrove swamps besides all shallow water reef environments while P. ligulata is only found on reef crests exposed to strong wave action (Veron, "Corals of the World"). P. damicornis is clearly a very adaptable species while P. ligulata is not.