Correcting Nutrient Instability by Kenneth WingerterOh, 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!
a.alegria5693 says October 7, 2020 at 3:39 pm Very informative ?. Keep up the good work. Reading you page on mandarin gobys helped me so much. Thank you Reply
tony_garcia18 says October 10, 2020 at 8:55 am I love it! Good stuff. This website always provides anything I need or questions I need asked. Reply
gerardobarbaro says October 12, 2020 at 8:21 pm This is very informative and educational to have a thriving reef. Reply
pumas0511 says October 1, 2020 at 9:00 am Water changes are very important in keeping nutrients instability Reply
Heatwave Reefer says October 1, 2020 at 10:02 am Testing and water changes as Pumas0511 stated is very important on keeping stability. Reply
Chris says October 1, 2020 at 11:26 am Macro algae and pods great for a reef tank at nutrient export Reply
Molvera18 says October 1, 2020 at 4:23 pm Water changes and consistency is key in nutrient stability Reply
adam.woods144 says October 1, 2020 at 4:55 pm Always do water changes quickest way to export nuisance nutrients Reply
Farhad says June 15, 2022 at 6:25 am Hello .I have pico reef tank I dont feeding my reef but nitrat dont rise under 10 . I change wather but don’t rise Reply
jose.caraveo1 says October 2, 2020 at 7:38 am I agree reducing the amount you feed your fish makes a big difference Reply
Nagaraviteja Gandla says October 2, 2020 at 8:59 am Knowledge is everything in reef tank success. Nice Article. Reply
gandla nagaraviteja says October 2, 2020 at 9:01 am Knowledge is everything in reef tank success. Nice Article. Reply
michaelbotzenmayer says October 2, 2020 at 3:34 pm Pods, phyto and a good source of outcompeting algea, and waterchanges Reply
michaelbotzenmayer says October 2, 2020 at 3:34 pm Pods, phyto and a good source of outcompeting algea, Reply
wendybsg says October 3, 2020 at 2:58 am 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 Reply
jeffery486 says October 3, 2020 at 4:50 am Great article, I’ve struggled a lot with GHA and it is hard to balance and overcome Reply
David Randall says October 3, 2020 at 10:06 pm Good refugium will help keep nitrites and nitrates in check Reply
chidibang316 says October 4, 2020 at 1:32 am Actually learned a few more things from this! Never assume you know it all already! Reply
email-3575 says October 5, 2020 at 7:03 am 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! Reply
Chell Slayton says October 5, 2020 at 10:16 am Thanks for this great info! Just what I need for my planted lagoon reef! Reply
Blythe Dyson says October 5, 2020 at 2:06 pm Been fighting diatoms for the last month good to know that Phyto and pods will also help outcompete! Reply
Timminy Moore says October 5, 2020 at 3:11 pm Very informative! Can’t wait to get my first frags! Reply
Lonnie Goldman says October 5, 2020 at 4:21 pm I have learned so much from your articles. Thank you for sharing your knowledge. Reply
John Graves says October 5, 2020 at 7:45 pm Great info! Nutrient imbalances are more common these days, more than when live rock was widely available. Reply
Teri Embum says October 6, 2020 at 12:47 pm Great information. Imbalances in nutrients can cause problems. Reply
Kyle Romanowski says October 7, 2020 at 9:19 am One of the more trying aspects of reefing IMHO… Reply
maxbears34 says October 7, 2020 at 3:42 pm A good refugium is the best way to keep nutrients stable. Reply
Robert Paniagua says October 9, 2020 at 9:04 pm Had the same problem nitrates low phosphates high very unbalance finally turning things around Reply
s_coffman says October 10, 2020 at 12:55 pm 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. Reply
Robert Bowers says October 11, 2020 at 6:37 am Water changes are a necessity. No home aquarium is perfect and water changes remove a lot of stuff from the tank. Reply
matthew j schwartz says October 11, 2020 at 9:29 am 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. Reply
matthew schwartz says October 11, 2020 at 2:10 pm Impotance of measuring high and low range nitrates Reply
Chad Whitmire says October 12, 2020 at 4:29 am 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. Reply
Andrew says October 12, 2020 at 10:46 pm Water changes being the most essential way for getting rid of excess nutrients seems to still be the most effective way until now. Reply
nicole morrison says October 13, 2020 at 4:33 am Great info make sure you test your water frequently.. Reply
nicole morrison says October 13, 2020 at 4:33 am Great info make sure you test your water frequently.. Reply
nicole morrison says October 13, 2020 at 4:34 am Great info make sure you test your water frequently.. cheato helps alot Reply
jenniferlye74 says October 15, 2020 at 8:37 am Always feels like the hardest to keep up with in reefing. Water change, water change, water change 🙂 Reply
Fabian Noggle says October 15, 2020 at 10:32 am 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. Reply
C Reab says October 16, 2020 at 4:25 am This is very useful information to have thanks for sharing. Reply
Sheldon Lewis says October 17, 2020 at 11:39 am I can’t seem to find a way to lower calcium in my tank but all other parameters have been pretty stable. Reply
TJ Saffioti says October 19, 2020 at 11:50 am Lots of good info, I appreciate the good knowledge! Reply
Brandon Rush says October 19, 2020 at 2:32 pm Don’t run your Nitrates too low or else you’ll kill everything! Reply
Leighla Wolfe says October 19, 2020 at 3:18 pm 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 Reply
Don says October 20, 2020 at 8:00 am 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! Reply
gabrielw94106 says October 21, 2020 at 10:51 am I always keep my water changes to a consistent time schedule to keep a sense of stability in my system Reply
meganpratt27 says October 26, 2020 at 3:11 pm So many different variables to consider! Thanks for the great info! Reply
meganpratt27 says October 26, 2020 at 3:18 pm Also, water changes have helped us immensely with keeping everything in order! Reply
devaji108 says October 27, 2020 at 10:12 am in all things nature starves for balance…our aquariums are the same. glad this is being talked about around the reef. Reply
rpkneumann says October 28, 2020 at 8:37 am Adding a refugium in my BioCube32. If only Cheato ws available. Reply
Scott says October 29, 2020 at 8:52 am Very informative. Thanks for putting this helpful information on your site! Reply
Jeremy Pryes says October 29, 2020 at 10:40 am I believe the tank takes a true year to stabilize. Reply
Josh Stevens says October 31, 2020 at 10:30 pm Nutritional is always good for stable echo system in your tank. Reply
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