Corals and nitrate

[JT101]

One thing that is the most perplexing about this hobby is the subject of nitrate and how they affect (or do NOT affect) corals.

For every thread and post I see about the criticality of keeping nitrates in a reef tank as low as possible, I have seen almost as many from people who report their nitrates to be 20, 30 or even higher and their corals thrive.

I find it hard to believe that these people with high nitrates in their tanks (with flourishing corals) are all liars.

Take the subject of brain corals for a moment…

In my tank, I have three trachys, a couple of bright green zoa colonies, a mushroom colony, three paly colonies, a plate coral and a leather coral. Out of all of these, the three trachys are doing the worst – yet I have ALSO heard time and time again that trachys are amongst the hardiest of corals!

It’s enough to make your head spin.

Now, for my question:

I see all the time posts about doing water changes to “bring your nitrates back down”. I agree this is perfectly sound advice. If you have a 24 gallon tank, have a nitrate reading of 30ppm and change 1/3rd of the water, you have just cut your nitrates down to 20ppm. If you do another 1/3rd change, your nitrates have just been knocked down to 13.3ppm. One more 1/3rd change and you are now down to 8.88ppm – not too bad. Problem is: How do you KEEP them down? What if you didn’t do anything drastic to your tank, and yet you see your trates are higher than they used to be? No dead fish, not overfeeding, you haven’t ADDED anything, yet your trates are higher than they used to be? What good is just doing water changes going to accomplish?

 

[Planet_Reef]

DON (Dissolved Organic Nitrogen) is a food source for many corals. How one coral reacts to various levels of Nitrates is going to vary widely amongst different species.

Everyone assumes that corals are only Phosphorus and Carbon limited but that is not the case. They are also Nitrogen limited.

Limited - means that it is required to sustain life. Absence of such item will prevent life.

Some corals can tolerate very high levels and some corals do not like N to be above a certain level.

 

[JT101]

DON (Dissolved Organic Nitrogen) is a food source for many corals. How one coral reacts to various levels of Nitrates is going to vary widely amongst different species.

Everyone assumes that corals are only Phosphorus and Carbon limited but that is not the case. They are also Nitrogen limited.

Limited - means that it is required to sustain life. Absence of such item will prevent life.

Some corals can tolerate very high levels and some corals do not like N to be above a certain level.

BINGO!!

THANK YOU!!!

You just said the magic words.

The problem is, which ones can handle nitrates, and which ones can't? I've never seen a chart or "nitrate rating" for the most popular corals.

All I have ever seen is "keep your nitrates as close to 0ppm as possible" being drilled into the head of every reef hobbyist.

 

[BigAl07]

John you want to "arrange" your tank to where it's liveable for the touchiest of your corals. In the ocean (for the majority) the NO3 reading is so small that our HOME test kits can't even read it. In very localized regions there may be a slight spike but for the majority of the planet it's extremely LOW. Why fuss with splitting hairs when you can just strive for <10 and have a thriving tank

 

[blue_eyes53813]

I have had a high nitrate problem in the past. Some corals tolerate it better than others... My galaxea coral for one was withdrawn the whole time. all other corals was fine.. I k now long term high nitrates can affect fish with there health as far as their lung and internal damage. But this is with pretty high nitrates for long periods of time


I think everybody that stresses on nitrates being an issue is afraid of that few corals that cant tolerate it or the long term affect on fish. We try to guide all hobbyist the the best direction for caring for all livestock.

 

[LPS_Blasto]

Think about it:

We use macro algae to absorb excess nitrates. Then we cut the macro algae out of the refugium and toss it in the trash. The point is PLANTS absorb nitrates as part of their essential nutrients.

The zoanthelle algae in our corals also uses nitrates to grow. I don't have any detectable nitrates in any of my tanks, but I also use DSB's and macro algae. It's entirely possible the algae is using the nitrates up so fast that my test will never be able to register any nitrates. GOOD! :laughroll Thats the whole point.

Any coral thats photosynthetic is going to benefit from tiny amounts of nitrates. As said above keep them under 10ppm and you should be good for most any coral.

 

[silverwolf72]

I see a difference between the ocean and our tanks, there a big difference between being dilute and readily available (the ocean)and being completely removed from our systems. IMO the only real problem with higher nitrates is that it also feeds algae which looks bad and may overgrow corals.

 

[JT101]

I did one more massive water change last night:

The night before, I measured 15ppm, did a 33% WC and (as calculated) it went down by 1/3rd to 10ppm (it's great when things actually work out as planned).

Last night, I feared that my 10ppm reading was going to be 15ppm again. I checked it - 10ppm. I breathed a sigh of relief. I did another 33% WC and measured 5ppm.

I won't do any more WC's for a few days but will monitor my nitrates daily.

I think if I keep it down to 5-10ppm I should be OK, as long as other params are not out of whack.

John

 

[BigAl07]

John that's just about GREAT! Of course ideal would be less but anytime I can see a tank maintain <10 I say Job well done!!

Keep up the good work and keep us posted! CONGRATS!!!