Are elevated nutrients a problem, or not?

[Randy Holmes-Farley]

Elevated nutrients are one of the most talked about issues in reefkeeping, with folks on all sides of the issue.

There is, however, no simple answer to the title question (IMO).

I thought I'd start a thread for a wide ranging discussion of this issue, and to gather many of the bits of data and anecdotes and comments in one place.

I'll start off with a few ideas to provide some background and ideas to debate.

1. It is clear that there are great reef tanks that most hobbyists admire with nutrients (nitrate and phosphate, particularly) ranging from low levels (say, less than 2 ppm nitrate and 0.01 ppm phosphate) up to quite high levels (>1 ppm phosphate and >100 ppm nitrate).

2. It is clear that there are reef tanks overrun with bryopsis, valonia, green hair algae, caulerpa, dinos, cyano, or other problems at nearly any of the values mentioned in 1.

3. Scientific studies on the effects of elevated nutrients on growth of hard corals are mixed. In some studies they thrive. In some studies they do not. In some studies, some growth forms (e.g., encrusting) are decreased and others (e.g., linear growth) of the same coral are increased. In most study cases, these are not getting the natural particulate foods they would get in the wild, and how much of what particulate foods they get in aquaria likely varies greatly based on husbandry techniques used.

4. Scientific studies on elevated nutrients in the ocean often suggest that hard corals decline and other organisms take over. This result is, of course, not due to solely to effects of nutrients on corals, but to effects on competing organisms as well.

Since a reef aquarium is, in some ways, a small microcosm of the real ocean, I think point 4 should not be dismissed, even knowing that point 1 is valid.

Perhaps point 1 is only valid for elevated nutrients if there are other aspects of the aquarium that allow hard corals to thrive. For example, herbivores to control algae.

Here, for example, is a recent analysis relating to hard corals in the ocean with elevated nutrients:

A new perspective of nutrient management of subtropical coastal stress-tolerant scleractinian coral communities

A new perspective of nutrient management of subtropical coastal stress-tolerant scleractinian coral communities

Elevated nutrients decrease the healthy status of coral communities, which can be stressful on reef corals, always resulting in decreased live sclerac…

www.sciencedirect.com

from it:

Elevated nutrients decrease the healthy status of coral communities, which can be stressful on reef corals, always resulting in decreased live scleractinian coral cover (LSCC).

 

[Miami Reef]

There will always be anecdotes/studies proving one side over the other.

Here’s my rationale: phosphate will probably not be limiting above 0.1ppm, so higher than 0.1ppm can only be suboptimal for calcification, thus stunting growth.

I remember a study where phosphate deficiency can cause coral bleaching, so I prefer to keep it above 0.02 ppm. Any lower, I start overfeeding and worrying. It seems easier to keep it detectable.

Regarding nitrate, I’m not sure if it has any effect on slowing growth. Ammonia might be preferred, and according to a study, nitrogen seems less likely to cause bleaching. As long as you feed your fish regularly, nitrate might not matter much.

To answer the question, I don’t think high nutrients kill corals. The worst that can happen is it can potentially slow growth and cause different colors in some SPS. To some, that is a problem, for others, not so much.

 

[Jason_MrFrags]

Go back and search for Richard Ross macna 2014. Its an interesting video to watch

 

[hunterallen40]

Very excited to see this thread, as this is something I think about a lot. My stance has wavered substantially since I started, but here is my current view...

I don't think there is any merit to claims that people's corals have died because of high nutrients. I think there are many that may see something perish, test nutrients, shrug and say "must be my phosphate," because this is the narrative that has been pushed for so long.

I think every hobby reference parameter chart I see says phosphate should be between 0.03 ppm and 0.05 ppm. This has become the boogie man, and I don't think this is justified.

Looking at the health of my animals, I have seen more vivid colors and better polyp extension with higher levels of phosphate. I personally have not seen a noticeable difference in growth rate.

I don't know what my phosphate is in my display right now, but I am very happy with how things are looking. I know if I test it I'll try to move it, so I just don't anymore.

 

[Randy Holmes-Farley]

Go back and search for Richard Ross macna 2014. Its an interesting video to watch

I expect he is likely to post to this thread, but what was your take away from his video?

 

[Randy Holmes-Farley]

Very excited to see this thread, as this is something I think about a lot. My stance has wavered substantially since I started, but here is my current view...

I don't think there is any merit to claims that people's corals have died because of high nutrients. I think there are many that may see something perish, test nutrients, shrug and say "must be my phosphate," because this is the narrative that has been pushed for so long.

I think every hobby reference parameter chart I see says phosphate should be between 0.03 ppm and 0.05 ppm. This has become the boogie man, and I don't think this is justified.

Looking at the health of my animals, I have seen more vivid colors and better polyp extension with higher levels of phosphate. I personally have not seen a noticeable difference in growth rate.

I don't know what my phosphate is in my display right now, but I am very happy with how things are looking. I know if I test it I'll try to move it, so I just don't anymore.

And I see a good herbivore (yellow tang) helping keep your tank free of algae!

 

[rtparty]

Rarely have I been able to prove high nutrients were causing an issue. Excess algae? Usually means lack of herbivores or lazy herbivores.

I can however point out very specifically what happens when nutrients are near to non existent. Dinos, faded colors, bleaching, etc

I actually don’t care what my nutrient levels are so long as some are there and with my fish load and feeding habits that’s all but guaranteed

 

[hunterallen40]

And I see a good herbivore (yellow tang) helping keep your tank free of algae!

Yes! This is very important, I think. I have not just that one, but six total (sailfin, powder brown, gem, achilles, yellow, white tail bristle tooth) and a foxface. They are constantly cleaning up the rocks. I only keep a couple snails, as the tangs do such a good job of keeping it clean. This is in a 320, so please don't come at me tang police haha.

In my experience, you get algae either way (as @Randy Holmes-Farley noted in point 2), so having a good cleanup crew is extremely important.

 

[Makara23]

My take: detectable nutrient during testing is the excess that corals don’t use. Corals would have used the ammonia and amino, and any access is the nitrate. As long you’re feeding the tank and have detectable nitrates and phosphates, I don’t think an exact number is crucial.

Although, I do believe too high of phosphate does bind to skeleton and hinders calcification. What that threshold is, I don't know. Nitrate in this case will be less relevant.

 

[o2manyfish]

I'm not a tester. If the tank looks good then be happy. If it doesn't then start checking the numbers. Since ICP testing got to the US about 8 years ago I started watching my Phosphate numbers. And they were high. On average over the last years my phosphates avergage 1.4 to 1.6 (Decimal point is in the correct place). For one period of almost 8 months it was runnng 2.2 to 2.4.

I was fortunate to be close to the ICP lab in the US and got to see alot of results. Results from public aquarias with thriving reeftanks and phosphate values as high as 4.4 - And some of these are public aquaria on the ocean using NSW (Treated) for their frequent water changes.

And one of the highest values I saw came from the incredible tank of Leng Sy. I forget what the value was, but it was the highest of the 100's of samples I saw.

From my personal experience color is not an issue with high phosphates. Colors are fantastic.

Is coral growth slowed? It's hard to compare growth rates because every tank is different and doing something different. But with my 1500g system having half the corals under LED Lighting and the other half lit by unfiltered sunlight - For sure in the sunlit frag tanks growth hindrance was not an issue.

Coral Calcification. I do think the higher phosphates does work against the calcification process. I haven't looked at the difference under a microscope, but corals grown under really high phos values (in my experience only) of close to 2.0 ppm or higher, the skeleton forms without issue and at an average rate but it's much weaker. The coral structure on some corals is almost brittle. Coral health, growth and color appear normal, But certain corals like digitata colonies and stylo colonies would break under their own weight. Lifting corals, not the delicate thin branched ones, to clean, check, frag you had to handle them delicately or you could frag them without the intention to. With the exception of coral branches over 3/4" thick. All the corals could be fragged with hands and without the need of tools.

When the phosphates came back down the structures went back to more normal. There was no difference visually in the growth from before super high, while super high, and after super high. But the structure strength in those 3 time frames is different.

About 2 years ago I felt that the colors of the corals were off and not what they were or could be. Did some testing and phosphates were at 1.2 and nitrates were at Zero. We started dosing nitrates, but had a crash before we could see the effects on the system.

For reference this is the display tank over the last few years with the phosphate values discussed above.

Dave B

 

[FrugalReefer]

My take: detectable nutrient during testing is the excess that corals don’t use. Corals would have used the ammonia and amino, and any access is the nitrate. As long you’re feeding the tank and have detectable nitrates and phosphates, I don’t think an exact number is crucial.

Although, I do believe too high of phosphate does bind to skeleton and hinders calcification. What that threshold is, I don't know. Nitrate in this case will be less relevant.

I’ve heard and read that excess PO4 doesn’t hinder calcification. PO4 is still able to bond to calcium carbonate crystals during calcification which results in a more brittle skeleton.

 

[PBar]

Hello,
in my opinion, there is small factor that is usually neglected during nutrients discussions in a home tank: ”tank age”.

I believe that there is a big different between new tank and a mature tank with regards to nutrients.

From my experience, a mature (famous “old” and packed) tank usually seems to handle a much broader range of these numbers without significant differences in the outcomes.

Curious to see if you have similar impression.

Cheers

 

[Dan_P]

Elevated nutrients are one of the most talked about issues in reefkeeping, with folks on all sides of the issue.

There is, however, no simple answer to the title question (IMO).

I thought I'd start a thread for a wide ranging discussion of this issue, and to gather many of the bits of data and anecdotes and comments in one place.

I'll start off with a few ideas to provide some background and ideas to debate.

1. It is clear that there are great reef tanks that most hobbyists admire with nutrients (nitrate and phosphate, particularly) ranging from low levels (say, less than 2 ppm nitrate and 0.01 ppm phosphate) up to quite high levels (>1 ppm phosphate and >100 ppm nitrate).

2. It is clear that there are reef tanks overrun with bryopsis, valonia, green hair algae, caulerpa, dinos, cyano, or other problems at nearly any of the values mentioned in 1.

3. Scientific studies on the effects of elevated nutrients on growth of hard corals are mixed. In some studies they thrive. In some studies they do not. In some studies, some growth forms (e.g., encrusting) are decreased and others (e.g., linear growth) of the same coral are increased. In most study cases, these are not getting the natural particulate foods they would get in the wild, and how much of what particulate foods they get in aquaria likely varies greatly based on husbandry techniques used.

4. Scientific studies on elevated nutrients in the ocean often suggest that hard corals decline and other organisms take over. This result is, of course, not due to solely to effects of nutrients on corals, but to effects on competing organisms as well.

Since a reef aquarium is, in some ways, a small microcosm of the real ocean, I think point 4 should not be dismissed, even knowing that point 1 is valid.

Perhaps point 1 is only valid for elevated nutrients if there are other aspects of the aquarium that allow hard corals to thrive. For example, herbivores to control algae.

Here, for example, is a recent analysis relating to hard corals in the ocean with elevated nutrients:

A new perspective of nutrient management of subtropical coastal stress-tolerant scleractinian coral communities

A new perspective of nutrient management of subtropical coastal stress-tolerant scleractinian coral communities

Elevated nutrients decrease the healthy status of coral communities, which can be stressful on reef corals, always resulting in decreased live sclerac…

www.sciencedirect.com

from it:

Elevated nutrients decrease the healthy status of coral communities, which can be stressful on reef corals, always resulting in decreased live scleractinian coral cover (LSCC).

My first contribution to this very interesting topic is to suggest that we keep in mind that we have conflated three topics: nutrient concentration vs algae growth, nutrient concentration vs coral growth, and algae growth vs coral growth. This might make things confusing when trying to render a thought.

I would say since the hobby‘s embraces the use of Cheato and other algae growth to reduce nitrate concentration, then the “algae growth vs coral growth“ concern is generally not, as far as macro algae exudates go, interfering with coral growth.

The “nutrient concentration v coral growth” concern is never clarified with the question of “which coral growth are bothered by nitrate and/or phosphate”. We have likely over generalized a scientific fact and created a misunderstanding about coral resilience to aquarium conditions.

Understanding the ”nutrient concentration vs algae growth“ is about as misunderstood as it is with coral. Let’s separate this one for another Randy question.

 

[Koty]

Is it wrong to claim that high phosphate and nitrates are the tip of the iceberg, telling us that our tank water is dirty and full of organic material?
That IMO may increase the risk of bacterial proliferation, some of which may be opportunistic. Thus, UV may be a good idea if you run high on nutrients.
FWIW, I recently read a paper in Nature comparing coral growth in Atols with or without nesting seabirds (that means guano that increases the nitrate and phosphate), and the corals grew much faster with the higher nutrients.
My nitrates are always around 10 ppm, and phosphate is rarely below 0.1, usually around 0.2. Based on the "literature" and the fact that I did not do any W/C for close to 2 years now, I was always afraid to add sps corals.

 

[Subsea]

Without herbivores, coral reefs would be algae dominated. Because I never left softies and went into filter feeding invertebrates, I encouraged high nutrients and numerous janitors in a mixed garden lagoon ecosystem. For growout systems, I use mollies as a cultivated algae control janitor. I just started using Blue Israeli Tilapia to control string algae in fresh water lilly pond and will experiment with adjusting some of these tilapia to full strength ocean.

Blue Tilapia

The Blue Tilapia is a freshwater fish with a high tolerance for brackish water. Adults are usually 5 to 8 inches in lengthand weigh 5 to 6 pounds. The largest recorded specimen was more than 21 inches long and weighed more than 10 pounds. Blue Tilapia are

tilapiadepot.com

“Oreochromis aureus, commonly known as Blue Tilapia, or Israeli Tilapia, is a species of fish in the Chichlidae family. The Blue Tilapia is a freshwater fish with a high tolerance to brackish (slightly salty) water. Adults are usually twelve to sixteen inches in length and weigh six to eight pounds. The largest recorded specimen was more than twenty-one inches long and weighed more than ten pounds.
Blue Tilapia are mouthbrooders, and broods range from 160 to 1600 eggs per female.

Tilapia serves as a natural biological control for most aquatic plant problems. Tilapia consume floating aquatic plants, such as duckweed water meal, most "undesirable" submerged plants, and most forms of algae. Tilapia rarely compete with other "pond" fish for food. Instead, because they consume plants and nutrients unused by other fish species, and substantially reduce oxygen-depleting detritus, adding tilapiaoftem increases the population, size, and health of other fish.

Blue Tilapia are commonly used with aquaponics, and are the number one seller because of their cold hardiness, surviving down to 50 degrees and can also withstand a high temperature of 98 degrees. Aquaponics is a sustainable food production system that combines traditional aquaculture (raising aquatic animals such as fish in tanks) with hydroponics (cultivating plants in water) in a symbiotic environment. Freshwater fish are the most common aquatic animal raised using aquaponics. In practice, tilapia are the most popular fish for home and commercial projects that are intended to raise edible fish. “


At some point in the discussion, DOC contributed by exudates from coral and DOC exudates contributed by algae should be considered and for that I encourage cryptic sponges. @Timfish hooked me on cryptic zone filtration.
Laissez les bonne temps roulee,

 

[MabuyaQ]

My believe is that nutrients (nitrate/nitrogen and phosphate/phosphorous) alone isn't painting the full picture. But that other factors like light and macro and micro elements (within a certain bandwithband possibly even ratio) also play an important in why we see the same problems at different nutrient levels and differences in presence of problems at the same levels.

 

[vetteguy53081]

I've run low levels and now semi-high levels and have realized the higher has worked well for me. These have been my best corals yet. What is semi-high. . . . .
My po4 is at .12 (used to be kept at .04 -.05)
My no3 at 27 ( used to be about 6)
My PH at 8.4 (used to be 7.9)

 

[areefer01]

I think an interesting slat to your question would be those that reply high, or low, or who cares should post images of their display. Sort of puts it into perspective.

 

[Subsea]

I think an interesting slat to your question would be those that reply high, or low, or who cares should post images of their display. Sort of puts it into perspective.

Newest tank
Mixed garden high nutrient lagoon.

 

[biom]

Elevated nutrients are one of the most talked about issues in reefkeeping, with folks on all sides of the issue.

There is, however, no simple answer to the title question (IMO).

I thought I'd start a thread for a wide ranging discussion of this issue, and to gather many of the bits of data and anecdotes and comments in one place.

I'll start off with a few ideas to provide some background and ideas to debate.

1. It is clear that there are great reef tanks that most hobbyists admire with nutrients (nitrate and phosphate, particularly) ranging from low levels (say, less than 2 ppm nitrate and 0.01 ppm phosphate) up to quite high levels (>1 ppm phosphate and >100 ppm nitrate).

2. It is clear that there are reef tanks overrun with bryopsis, valonia, green hair algae, caulerpa, dinos, cyano, or other problems at nearly any of the values mentioned in 1.

3. Scientific studies on the effects of elevated nutrients on growth of hard corals are mixed. In some studies they thrive. In some studies they do not. In some studies, some growth forms (e.g., encrusting) are decreased and others (e.g., linear growth) of the same coral are increased. In most study cases, these are not getting the natural particulate foods they would get in the wild, and how much of what particulate foods they get in aquaria likely varies greatly based on husbandry techniques used.

4. Scientific studies on elevated nutrients in the ocean often suggest that hard corals decline and other organisms take over. This result is, of course, not due to solely to effects of nutrients on corals, but to effects on competing organisms as well.

Since a reef aquarium is, in some ways, a small microcosm of the real ocean, I think point 4 should not be dismissed, even knowing that point 1 is valid.

Perhaps point 1 is only valid for elevated nutrients if there are other aspects of the aquarium that allow hard corals to thrive. For example, herbivores to control algae.

Here, for example, is a recent analysis relating to hard corals in the ocean with elevated nutrients:

A new perspective of nutrient management of subtropical coastal stress-tolerant scleractinian coral communities

A new perspective of nutrient management of subtropical coastal stress-tolerant scleractinian coral communities

Elevated nutrients decrease the healthy status of coral communities, which can be stressful on reef corals, always resulting in decreased live sclerac…

www.sciencedirect.com

from it:

Elevated nutrients decrease the healthy status of coral communities, which can be stressful on reef corals, always resulting in decreased live scleractinian coral cover (LSCC).

It looks like most corals of interest in this hobby can adapt to this crazy elevated nutrients in our tanks, but IMO they need time to adapt. I agree there are big, established aquariums thriving at 2 ppm phosphate and 100 ppm nitrate but I seriously doubt a new tank has a big chance to survive starting with such elevated levels.

About SPS coloration and nutrient levels from my experience it was easier to keep bright pink, yellow and light blue acros at the lower end of nutrient levels (0.03 PO4 and 1-2 ppm NO3). I am not saying those colors are better, not everybody likes this Zeo type pastel colors but I really do .