Is nutrient control an effective method of treating algae in a reef?

[rock_lobster]

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[ca1ore]

I think reefkeepers have been caught up on the idea that the pristine reefs don't have ANY algae and it is a pest that shouldn't be there.. However if you take a closer look at any reef you will see that there are 100s of billions of herbivores there in the same habitat that the coral is growing in. Therefore it should be obvious that all of these grazers are eating something and that the reefs pristine water isn't what prevents algae from growing.

I have argued this exact point for years. My system, in the main, is a big display, large refugium and frag tank. Not a wisp of algae in the display, some in the refugium, and it's a constant problem in the frag tank. Same water throughout the system, so nutrient levels in each tank are the same. What's the difference: herbivores. Lots of them in the display, a couple in the refugium and none in the frag tank. It's quite amusing to watch all the tangs, butterflyfish and angels crowd around a frag that I move out of the frag tank. Within an hour it is fully cleaned of any algae.

At the end of the day, though, I think it is neither one at the exclusion of the other..... it is both! You want to try to maintain low nutrient, but not NO nutrients; and you want the right balance of herbivores. It complicates things that some individual tangs, for example, decide they don't like algae versus others that do. My scopas, for example, eats no algae at all, ever. Mud brown lump of useless.

 

[nautical_nathaniel]

I still think some nutrient control is needed, especially on reef tanks. Most successful reefs have a refugium and a skimmer for a reason. But it's also a balancing act, too many critters and too much food and you're bound to have algae issues, even if every fish in the tank is a herbivore.

 

[rock_lobster]

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[ca1ore]

I actually don't even test for phosphate or nitrate ..... and I feed my tank a TON. I just eyeball it, and if something appears amiss then I go and dust off the test kits. When I did test regularly, both P and N were un-measurable on the API kits. Does not mean zero, of course, but below the testing threshold. I do run pretty aggressive export mechanisms .... and employ a lot of herbivores (mostly fish). And, FWIW, one or more of my fish (not entirely sure whom) also eats aiptasia (and majanos). It's all over my sump, fuge and frag tank, but not one visible in the display.

 

[Martin Kuhn]

I also think there is not only way to achieve a great tank, there are several.

Achieving pastel like SPS coloring, eg, is simply easier with ULNS systems. Living on the edge, of course, is not everybody’s favorite.

Much more important than to reach a certain nutrient level (.... and where should it be ?...) in my eyes is to keep the levels constant for a longer period of time. Corals acclimate to conditions they live in.

 

[rock_lobster]

I also think there is not only way to achieve a great tank, there are several.

Achieving pastel like SPS coloring, eg, is simply easier with ULNS systems. Living on the edge, of course, is not everybody’s favorite.

Much more important than to reach a certain nutrient level (.... and where should it be ?...) in my eyes is to keep the levels constant for a longer period of time. Corals acclimate to conditions they live in.

I think SPS are somewhat tolerant of lower nutrient levels but most other coral included LPS and softies not so much. My SPS colonies started to RTN from the base up pretty quickly after my phos was at undetectable for an extended period of time though the color was still great even while it was dying. I agree though consistency definitely helps.

 

[Susan Edwards]

My one tank, 1.5 years old, has consistantly had nitrates 20-160 and everything is growing and thriving. No real algae issues either and no algae eating fish. Cuc is low--snails and 2 hermits. I am trying to get nitrates down to the 20-40 range though as I'm seeing some algae returning. My goal is 20, with po4 at .1. Currently at 4.6 (lazy about rinsing frozen foods most likely). The coral frag tank and the new 125 both also run 40-80 and am also working to get them down. I feed heavy, even the coral tank as it is bursting at the seams with pods so I toss in pellets. Again, no algae in tanks. Lots in the one sump. I think it boils down to preferences, comfort level, and how your tank is doing overall.

 

[ca1ore]

Much more important than to reach a certain nutrient level (.... and where should it be ?...) in my eyes is to keep the levels constant for a longer period of time. Corals acclimate to conditions they live in.

Well of course stability is important, that's reefing 101. Absolute levels are important only if you are outside the 'range' ..... and I don't think anyone really knows what that range is LOL.

 

[cracker]

Much more important than to reach a certain nutrient level (.... and where should it be ?...) in my eyes is to keep the levels constant for a longer period of time. Corals acclimate to conditions they live in.

I for one can't get a consensus on what those nutrient levels should be either. There are just far too many opinions on this. I got tired of searching so now I try to match Dr Randy's & Mcarrol's suggested range.
Mcarrol is more lenient than Randy's range. This way I have an idea of the numbers I need with no headache. Then see how the tank looks. I hope that after time,(a long time for me it seems) I'll get the idea & have my "own" preferred range !

 

[Randy Holmes-Farley]

Bear in mind the low phosphate regimen they tested in that paper is lower than needed to control some types of algae: 0.006 uM, which is only 0.0006 ppm.

 

[rock_lobster]

Bear in mind the low phosphate regimen they tested in that paper is lower than needed to control some types of algae: 0.006 uM, which is only 0.0006 ppm.

many people were (and still do) target undetectable or low as possible phos as the best range for controlling algae in reef tanks. This article does contract that idea.

What range would you suggest as a level of phos to control algae growth?

 

[Randy Holmes-Farley]

many people were (and still do) target undetectable or low as possible phos as the best range for controlling algae in reef tanks. This article does contract that idea.

What range would you suggest as a level of phos to control algae growth?

The issue in a reef tank (or in the real ocean) is more complicated than this article might suggest since corals can also get N and P from foods, but in general, I think a target of 0.02 to 0.03 ppm phosphate is a good balance between many competing issues (pest algae, pest dinos, coral health, etc.).

If you have a particular situation you may want to target higher or lower levels, temporarily or permanently.

 

[Paul B]

Nutrient control and algae is an old wives tale, just ask an old wife. Of course algae needs nutrients but it needs so little that it doesn't matter. If you put clean seawater with zero everything in the sun, it will grow algae. My nitrates are 160 and my po4 is 2.0. See any algae? I even have a hard time growing it on my algae scrubber. There is something else that spurs algae and I don't know what it is. But no one else does either. If they did, it would be easy to control. But it does grow on every healthy reef in the sea.

 

[Randy Holmes-Farley]

Nutrient control and algae is an old wives tale, just ask an old wife. Of course algae needs nutrients but it needs so little that it doesn't matter. If you put clean seawater with zero everything in the sun, it will grow algae. My nitrates are 160 and my po4 is 2.0. See any algae? I even have a hard time growing it on my algae scrubber. There is something else that spurs algae and I don't know what it is. But no one else does either. If they did, it would be easy to control. But it does grow on every healthy reef in the sea.

One thing I do agree with you on, and is certainly correct, is that very high nutrients does not "cause" algae. If all other conditions for growth are met, it permits growth.

I can list at least a dozen things that algae critically needs to survive, including chemicals and other factors. The fact that your system uses one other than availability of N and P to limit algae growth is hardly evidence that limiting N and P doesn't work.

The trick is not knowing what algae needs to survive and thrive. Most scientists know the list, and we do not keep it a secret.

The trick is getting that limiting thing to impact all of the species of pest algae that reefers might worry about, and not any of the other organisms they desperately want to keep alive. That cuts down the available list of "solutions" quite a bit.

 

[Paul B]

One thing I do agree with you on, and is certainly correct, is that very high nutrients does not "cause" algae. If all other conditions for growth are met, it permits growth.

I agree and it may be the first thing we agree on.

I can list at least a dozen things that algae critically needs to survive, including chemicals and other factors. The fact that your system uses one other than availability of N and P to limit algae growth is hardly evidence that limiting N and P doesn't work.

That is of course also true, but the majority of fish posts seem to hone in on nitrates and phosphates. There is very little mentioning of iron, magnesium, silicon, calcium, potassium, sulfur or any trace elements like copper, zinc, cobalt or molybdenum and we don't normally test for them. All those things are needed to grow algae even if some are minute trace elements. (I am sure you know 10 more ) Nitrate and phosphate are mentioned in just about every thread of algae and they can be through the roof and algae still "may" not grow.
I doubt we can also control algae growth just with nutrients because much of it comes in food, sand, rocks or NSW. Which is why I normally say to forget nutrients and let the stuff grow. But force it to grow on something that you can remove to clean like a scrubber. You will go nuts, like most people do chasing numbers. Corals are different. If you want colorful SPS corals, high nitrates may not be the best thing, but it seems a lot of SPS corals like high nitrates as my montipora seem to prove. And this thing, whatever it is.
This hard coral grew from a tiny frag to about 7" across with my nutrients.



And duncans also seem to thrive with high nitrates. Who Knew!

 

[Sallstrom]

I saw a lot of nice algae last week snorkelling on the reefs in the Red Sea. They grew in the tidal zone where there were less big fish and other herbivores. Deeper down there where almost no algae.

Algaes from the reef probably like the same water parameters as the corals from the same region

/ David

 

[Hans-Werner]

The problem with low phosphate concentrations in reef tanks is that for example hair algae, Bryopsis and cyanobacteriae have access to phosphate stored in sand, gravel and rocks while the corals have not, simply because the algae and cyanobacteria are growing on these substrates. Running low phosphate concentrations will starve the corals and not the algae. Phosphate depletion is only effective on the very long term and preferably at the concentration Randy already mentioned. It is much better to control algae over the nitrogen supply. There is no N storage in the rocks or other minerals, corals have the same access to dissolved N as algae have and corals are extremely efficient in taking up N compounds like ammonia, nitrate, amino acids and urea, in fact more so than algae. In many reefs corals are phosphorus limited while at the same time algae are N limited. This means algae are less efficient in taking up N compounds.

If you run extremely low phosphate concentrations you will starve the corals, reduce competition for nitrogen compounds and trace metals and you will get more hair algae, Bryopsis and cyanobacteria than with let´s say 0.1 ppm phosphate.

 

[a-mused]

The rules I run by:
a) make sure there are no macro algae in the system (bryopsis, bubble, etc) - if there is, treat with fluconazole first to eliminate the problem. You'll find that your phosphates will rise after being released by the macro algae die-off.
b) Now that you have free phosphate that can be used by the corals, feel free to keep it anywhere between 0.03 and 0.1.
c) live by the Redfield Ratio (NO3[ppm] / 65) / (PO4[ppm] / 95). You're aiming for 16. ..16 mol of NO3 to 1 mol of PO4.

As long as the ratio is right around 16, PO4 is at 2 or lower, levels of NO3 around 15 are fine and shouldn't cause algae issues. Here's a link to a chart for reference. Note that mg/l is the same as ppm (thank you, metric system!). There's simply no need to starve a reef tank when there's an optimal ratio between NO3 and PO4 that's been around 80 years and has proven itself out time and time again. You can find similar charts that give a little more leeway in the numbers, but the goal of all of them is to keep that ratio as close to 16:1 as possible. Do note that I'm not recommending you run your PO4 at 2. That can cause CaCO3 uptake issues with some corals. When reading the chart, please mentally convert the commas to decimal points (rest of the world vs. US notation).

http://www.dansreef.co.uk/wp-content/uploads/2018/01/RR.jpg

 

[Sallstrom]

The rules I run by:
a) make sure there are no macro algae in the system (bryopsis, bubble, etc) - if there is, treat with fluconazole first to eliminate the problem. You'll find that your phosphates will rise after being released by the macro algae die-off.
b) Now that you have free phosphate that can be used by the corals, feel free to keep it anywhere between 0.03 and 0.1.
c) live by the Redfield Ratio (NO3[ppm] / 65) / (PO4[ppm] / 95). You're aiming for 16. ..16 mol of NO3 to 1 mol of PO4.

As long as the ratio is right around 16, PO4 is at 2 or lower, levels of NO3 around 15 are fine and shouldn't cause algae issues. Here's a link to a chart for reference. Note that mg/l is the same as ppm (thank you, metric system!). There's simply no need to starve a reef tank when there's an optimal ratio between NO3 and PO4 that's been around 80 years and has proven itself out time and time again. You can find similar charts that give a little more leeway in the numbers, but the goal of all of them is to keep that ratio as close to 16:1 as possible. Do note that I'm not recommending you run your PO4 at 2. That can cause CaCO3 uptake issues with some corals. When reading the chart, please mentally convert the commas to decimal points (rest of the world vs. US notation).

http://www.dansreef.co.uk/wp-content/uploads/2018/01/RR.jpg

Please explain why this ratio N/P will keep algae away. I don't see why algae shouldn't like the same water conditions as the corals(if the corals prefer that ratio is another question).

/ David