Oh, the paradox of algae. They have ruined many tanks–even caused some frustrated aquarists to leave the hobby forever. Yet, our tanks (especially reef tanks) cannot thrive without them–think zooxanthellae. Getting that perfect balance of nutrients, principally nitrate and phosphate, can be exceedingly difficult to ever attain, much less maintain.
Part of this challenge lies in the tendency for these and other essential nutrients to fluctuate independently of each other. That is, you can “run out” of nitrate and still have super high concentrations of phosphate, and vice versa.
We usually talk only about nutrient excess, but not imbalance. Imbalances do, however, occur and cause significant problems. A substance that is required for growth, but can be scarce in the environment, is termed a “limiting nutrient.” Even if all other essential substances are present, the growth of algae and many bacteria cease once a limiting nutrient is depleted.
Great, right? Don’t we want algae to not grow in our reef tanks?
Think of it this way; yes, the growth of nuisance algae is irksome, and as mentioned above can straight-up ruin an aquarium. But it is a symptom of a larger, more systemic, problem. Algae grow when there is an overabundance of nitrate and phosphate. Sure, you can get rid of all of the nitrate–or all of the phosphate–and the algae will stop growing (including your desirable macroalgae). Yet, some problems will remain if you don’t reduce BOTH nutrients. Sure, you got rid of the algae problem by removing all of one nutrient. But left in the tank at high concentrations, the OTHER nutrient can still cause health problems for your aquarium animals–either directly or by messing up other important water parameters.
You can add all of the macroalgae you want, but they won’t remove that excess nitrate if they can’t grow, and they can’t grow if there isn’t some tiny amount of phosphate. In this case, one might actually add miniscule doses of potassium phosphate until the nitrate is almost gone (and before the phosphate starts to accumulate!). Another simpler, option is to perform large water changes to dilute the excess nutrient down to acceptable concentrations. Either way, you’d also have to reduce fish feeding/stocking to help ensure that nutrient levels don’t spike again!
So, what about carbon dosing? Algae use inorganic carbon (i.e. carbon dioxide) as a carbon source. Their growth cannot be enhanced by adding an organic carbon source such as ethanol. Heterotrophic bacteria, on the other hand, do utilize these carbon sources. Indeed, as you feed these microbes, and promote their growth, they’ll sequester both nitrate and phosphate from the water column and other areas the system. For this reason, aquarists carbon dose as to “steal” the excess nutrients from nuisance algae. Of course, most carbon dosing targets aerobic bacteria (which respire and produce carbon dioxide), so there is still a risk of algal blooms when employing this method.
But, here too, if a limiting nutrient has been depleted, these microbes might not be able to grow properly. Indeed, all you’ll be doing by carbon dosing, in this case, is further polluting the water by adding a bunch of organics that won’t get “eaten.”
There is one case where carbon dosing can be used successfully to restore nutrient imbalance where nitrate has been depleted but phosphate remains in excess–when dosing is carried out alongside the inoculation of diazotrophic (i.e. nitrogen-fixing) bacteria. Diazotrophs such as R. palustris are able to make fixed nitrogen (make ammonia out of nitrogen gas). No worries… They only do this under conditions of extreme nitrogen scarcity, and the bulk of ammonia they synthesize is immediately used to build amino acids/proteins (i.e. biomass) rather than dumped into the surrounding water. Indeed, they serve as important in-house symbiotic fertilizer factories for zooxanthellae, thereby allowing corals to grow rapidly in the nutrient-poor waters in reef habitats. Because these anaerobic microbes can supply their own fixed nitrogen, they keep sequestering phosphate even after ammonia/nitrite/nitrate has been depleted from the environment!
Ideally, both nitrate and phosphate should be maintained low–something like 0.5 to 1.0 ppm NO3 and 0.1 to 0.2 ppm PO4. The lower ends of these ranges are probably best, and would not at all be low compared to a healthy natural coral reef. While these are fairly low levels (compared to magnesium or potassium, for example), note that each range spans a doubling in concentration from the low to high ends. So, don’t just aim to stay within the range, but at a particular value. Stability is key!
You already know how to not introduce more nutrients than your system can manage: Don’t overstock, don’t overfeed, and don’t skimp on the water changes. But a planted refugium can help in overall nutrient control. Same with live phyto! If both nitrate and phosphate tend to be high, and carbon may be limiting to heterotrophic bacterial growth (for example, if you use heavy chemical filtration), then carbon dosing might help. But if nitrate appears to be low while phosphate is high, you may want to bolster your microbiological community with diazotrophic bacteria before resorting to any carbon dosing regimen. And finally: Test often!
kris1351 says
Great information!
aquamane says
^
a.alegria5693 says
Very informative ?. Keep up the good work. Reading you page on mandarin gobys helped me so much. Thank you
Regina Heitschmidt says
You said it!
kevin.guerrerodc5 says
Thanks for the info
tony_garcia18 says
I love it! Good stuff. This website always provides anything I need or questions I need asked.
gerardobarbaro says
This is very informative and educational to have a thriving reef.
pumas0511 says
Water changes are very important in keeping nutrients instability
extremesteam says
Definitely water changes
randles.17 says
Great information
Heatwave Reefer says
Testing and water changes as Pumas0511 stated is very important on keeping stability.
mlashawnbenton says
keep doing those water changes.
Chris says
Macro algae and pods great for a reef tank at nutrient export
cnawn says
The best way to prevent algae.
Molvera18 says
Water changes and consistency is key in nutrient stability
angelyrojas23 says
Great ? information
Tom says
Good info.
adam.woods144 says
Always do water changes quickest way to export nuisance nutrients
Jamie wesenberg says
Thanks for the info
Farhad says
Hello .I have pico reef tank I dont feeding my reef but nitrat dont rise under 10 . I change wather but don’t rise
Jacob Wright says
Amazing information as always!
Alfie Henshaw says
Great article
Tracy Schultz says
Awesomeness
devon maynard says
Awesome information
Joe Camejo says
Don’t chase numbers, keep them consistent.
jose.caraveo1 says
I agree reducing the amount you feed your fish makes a big difference
Nagaraviteja Gandla says
Knowledge is everything in reef tank success. Nice Article.
gandla nagaraviteja says
Knowledge is everything in reef tank success. Nice Article.
Juan Carlos Perez says
Good read.
michaelbotzenmayer says
Pods, phyto and a good source of outcompeting algea, and waterchanges
michaelbotzenmayer says
Pods, phyto and a good source of outcompeting algea,
michaelbotzenmayer says
Great source of info
chadtadams says
Great
radoingermany says
Good info
Jordn Gerardot says
Awesome reed ?
Dallas Tippie says
Fantastic read!
wendybsg says
This article was written about my tank! Happened to me yesterday…lost a hammer. My nitrates were bottomed out and my phosphates screaming off the chart. We added carbon to my filter and feeding all mysis. The issue is I have never tested because I was told they were dangerous chemicals, so I have always had my store test for me. But this has changed since yesterday! I am now learning how to test my 3 year old tank. Not boasting, but I feel a little empowered by this. I feel like I am a conqueror and putting on my armor and standing against the unknown (because I am still learning).
Thank you for the article, I have saved it to my notes so it can be read again and again.
~Wendy
jeffery486 says
Great article, I’ve struggled a lot with GHA and it is hard to balance and overcome
emailme says
It’s definitely a delicate balance.
DANIEL E SCHLAGMAN says
Interesting!
DANIEL SCHLAGMAN says
Very interesting
Troy Simizon says
Great information
Ricardo says
Always learning something new ???
David Randall says
Good refugium will help keep nitrites and nitrates in check
zadok says
Great read! Thanks for writing this
zadok says
Great read! Thanks for writing this!
zadok says
Great read! Thanks for writing this!!
chidibang316 says
Actually learned a few more things from this! Never assume you know it all already!
jayfl77 says
Great ? information
dcreeron says
Info every reefer needs to be aware of!
tyler.powell says
great read
Brett says
Solid input!
Jesse says
Great info as always!
email-3575 says
Great content, as usual. Thanks for sharing! Creating the balance for a tank is one of the most difficult things to accomplish but once that high level of stability is met, the results can be amazing!
email-3575 says
Great content, as always! Thanks for sharing.
Chell Slayton says
Thanks for this great info! Just what I need for my planted lagoon reef!
Blythe Dyson says
Been fighting diatoms for the last month good to know that Phyto and pods will also help outcompete!
Timminy Moore says
Very informative! Can’t wait to get my first frags!
Ed Fischer says
Test Test Test
John hernandez says
Much needed info
Lonnie Goldman says
I have learned so much from your articles. Thank you for sharing your knowledge.
gbrag64 says
Great info
Mr Papu says
Great read
Bob Escher says
Love this information
Bob Eschet says
Great Information, I have been doing this
Kevin says
Water change gang! ???
John Graves says
Great info! Nutrient imbalances are more common these days, more than when live rock was widely available.
Jorge Cabrera says
Testing &water changes are super important.
aquamane says
it all boils down to consistency!
motor795 says
Knowledge is everything
Andrew Welsh says
Some interesting information
Lisa says
Explained perfectly, thank you!
Derek Nguyen says
Very great information and insight!
chris says
consistency = stability , don’t chase parameters!!!
Teri Embum says
Great information. Imbalances in nutrients can cause problems.
Elizabeth Nitz says
Thanks for the great info!
Ken Bilow says
KEEP ON TESTING
Kyle Romanowski says
One of the more trying aspects of reefing IMHO…
maxbears34 says
A good refugium is the best way to keep nutrients stable.
Larry says
Do not overfeed
Shawn Vest says
Great article
Adam Krause says
Sweet!!
Kelly VanAuken says
Very informative.
Elizabeth Dusser says
Great info
Christopher Skates says
I didn’t know all of this. Good to know!!
Casey says
Awesome Read. Love your blog post!
Shawn Dear says
Learned so much
Suriyun Soukhamneut says
Its all about that balance!
agatheri says
great read needed this
jason says
water changes are the key.
Robert says
Wish I seen this info before
Robert Paniagua says
Had the same problem nitrates low phosphates high very unbalance finally turning things around
Andrew Welsh Welsh says
Some very interesting information
justan jenkins says
that all sounds super complicated…
Ramon Mateo says
interesting read
s_coffman says
The struggle is real lol. Monitoring the nitrates along with everything else Is a constant balance. Food load, stock load, maintenance, temperature changes, Corals fighting or spawning, piggybacking in algy. You have to pay attention to all of parameters.
mstrait44 says
Good info here
chris.oceguera says
Water changes and stability
Roberto Castro says
A lot of great information
Roberto Castro says
Thanks a lot for the info
bellboy63055 says
Great read
bellboy63055 says
Great info
Robert Bowers says
Water changes are a necessity. No home aquarium is perfect and water changes remove a lot of stuff from the tank.
matthew j schwartz says
One very important part of nitrates that is always left out is the importance of not just testing for 1 type of nitrates. It is a must to test for both low and high range nitrates.
matthew schwartz says
Impotance of measuring high and low range nitrates
Chad Whitmire says
I’ve gone away from using GFO and Biopelets. Now I only use a refugium with natural filtration. So much easier and a lot less expensive. Thank you Algae Barn for all the knowledge that you all pass on.
chahine29 says
Thanks for the info
Matt Traylor says
Great article! Tons of useful info!
Mike says
Good info, never thought about carbon dosing.
Linda Montgomery says
Great info
Andrew says
Water changes being the most essential way for getting rid of excess nutrients seems to still be the most effective way until now.
Bob Trimper says
learned a lot!
nicole morrison says
Great info make sure you test your water frequently..
nicole morrison says
Great info make sure you test your water frequently..
nicole morrison says
Great info make sure you test your water frequently.. cheato helps alot
rpg56185 says
Keep up on those wc!
bsmurray90 says
Good to know
trevorpem10 says
Pods! The backbone of the tanks cleanup crew.
Victoria Joy Brewer says
Great info.
Victoria Joy Brewer says
Great info.
Usman Qamar says
Great helpful read! thanks!!
SAMANTHA MARTIN says
Good to know!!
Mark Clark says
Regular water changes and don’t overfeed.
jenniferlye74 says
Always feels like the hardest to keep up with in reefing. Water change, water change, water change
B says
Always a struggle with nutrients
Fabian Noggle says
well i can tell everyone straight out there are times that there is nothign you can do but start over from scratch, that is to say i have seen on a couple occasions that daily water changes, macro algae, algae scrubber, etc. would lower or eliminate nutrients, and one case was a large tank( 150/160 ish gallons) that had 3 coral frags, and 4 fish, and a small cuc of 3 hermits, and a few snails.
C Reab says
This is very useful information to have thanks for sharing.
cyberkiller6 says
Chaeto good
Sheldon Lewis says
I can’t seem to find a way to lower calcium in my tank but all other parameters have been pretty stable.
TJ Saffioti says
Lots of good info, I appreciate the good knowledge!
andrew babcock says
Interesting
shanemsalhus-7885 says
excellent source of info, very thorough!
Brandon Rush says
Don’t run your Nitrates too low or else you’ll kill everything!
Leighla Wolfe says
How I corrected nutrient instability (hair algae and cyano)
1. SMALL weekly water changes for stability (marching ph and salinity)
2. Investing in a RODI water system, ATO, and inkbird for temp balance
3. Refugium with awesome phyto and pods!
4. Lighting schedule with refugium opposite of main tank for pH balance!
5. Finding the cause! Overfeeding for instance, lack of flow, detritus buildup
Mark Clark says
Great information
Don says
Time and patience! A refugium helps, in laymen terms, grow algae in your sump vs your display tank. I use RedSea Nos/Pos and dose with Nitrate as needed. Maintain phosphate at 0 and nitrate at .5-.1. Also helps with the tanks PH dips at night. Make subtle adjustments and wait 4-6 weeks testing at least 2X a week to maintain the proper levels. It’s a hobby not a chore – you’re not alone. Happy Reefing!
Kurt Kidder says
Awesome
gabrielw94106 says
I always keep my water changes to a consistent time schedule to keep a sense of stability in my system
michael_barrioz says
Great article!!
Justin Walz says
Keeping the fauna and flora crucial
lapisyogajulianne says
So informative.. thank you
Jelani Register says
Great article thank you!
William Benavides says
Great info
jhernandez16172 says
Nice Info
oodydog says
Love
your articles
weshamand says
Keep on top of your water changes.
Donald Christman says
Never over feed
meganpratt27 says
So many different variables to consider! Thanks for the great info!
meganpratt27 says
Also, water changes have helped us immensely with keeping everything in order!
devaji108 says
in all things nature starves for balance…our aquariums are the same. glad this is being talked about around the reef.
rpkneumann says
Adding a refugium in my BioCube32. If only Cheato ws available.
Scott says
Very informative. Thanks for putting this helpful information on your site!
Jeremy Pryes says
I believe the tank takes a true year to stabilize.
Josh Stevens says
Nutritional is always good for stable echo system in your tank.