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Quick fix for nitrate spike?


Mar 10, 2020
We've been having some nitrate spikes in our water system, and while we are exploring long term options for prevention, I was wondering if anyone could suggest any of the immediate additives that should reduce nitrates quickly when that happens. I listed a bunch of examples I found below. Any work better or worse than others? We used some Purigen but it didn't seem to do much.




Hello! What levels are your nitrates spiking to? How many gallons is your system? Do you have sand or other live nitrogenous waste producing organisms in your system? These answers will help us provide a more accurate diagnosis and advice.
Nitrates are spiking to over 60-80. The system is large - 8 tanks that are probably 55 gallons, 18 tanks that are probably 20 gallons, and a large sump, all connected. Most tanks are unoccupied, 7 have octopus, some contain algae refugium, and some contain snails, shrimp, and horseshoe crabs that rotate tanks as a cleanup crew and aren't additionally provisioned. We believe the issue was that the substrate was not getting cleaned. Some tanks have sand and others have gravel, and there is also a lot of live rock in the system. But, we believe that there was too much detritus stuck in the gravel substrate.

Any other thoughts would be great, especially with ideas about how to quickly lower the levels. Many say nitrates won't kill the octos, but the activity of the octos has decreased substantially since the levels rose.
Do you have a protein skimmer? That might help, and also to pick up after your octopuses (uneaten food, shells, etc). Some food is messier than others, such as mussels, so you might offer food that will be completely eaten or results in remnants that are easy to clean up. I often used pieces of shrimp.

It is possible to vacuum the sand or gravel, but I don’t know of instances where this is done in an octopus tank. It’s more common in maintenance of tropical fish and live rocks.

I would recommend against using a chemical agent to lower the nitrogen levels in the tank. While 60-80 is high and can be alarming, adding more chemicals to the water (which will no doubt put increased stress on the animals in the system) could push the system over the tipping point. I have only ever used products like amquell in very large systems (500 plus gallons) with teleosts, and only when my nitrites were starting to increase alongside my nitrates.

I would recommend doing more frequent, larger water changes to lower the amount of nitrogen, along with a gravel wash (using a large tube attached to a spihon, I can give more clear instructions if you don't know what I mean) and a protein skimmer (or 3 due to the size of your system) as suggested by @Nancy .

Your animals should be okay with nitrates around 60-80 for a week or so, and can survive lower levels for longer. Any large swings in water chemistry can stress out your animals, including a sharp and rapid drop in Nitrates. I know it is stressful and can be worrying, but I caution you against making large dramatic changes to your system through the use of additives and chemicals, when you can most likely reduce the amount of nitrogen through increased water changes and more diligent tank maintenance.

Another thing you can do is to reduce the volume of water on your system. If the majority of your system is unoccupied, why not remove the tanks from the system and set them back up again once you need them to house animals? Reducing the number of tanks and the total volume of the system can help you have more direct control over the water chemistry, and can prevent situations where you may have old or dead things in tanks that have gone without use for many weeks/months which can lower your water quality.
Another thought- you could check your aeration in your biomedia as well. The bacteria that lives there needs oxygen to grow and reproduce, so if you don't have an airstone underneath your media you could be hampering their efficacy.
I am not a huge fan of any sort of liquid treatment. That said, biopellet reactors are a nice way to go and NO3:PO4-X aka nopox is the same thing and faster. It works on the principle of introducing aerobic denitrifying bacteria which consumes nitrates and phosphates far quicker than anaerobic bacteria does and also introduces a form of elemental Carbon (essentially a sugar source) into your tank. This requires good skimming and it doesn’t hurt to add mesh filter socks which can also help to remove the bacteria. Make sure to monitor carefully, though,as this aerobic bacteria can choke out your system. Nopox is pretty expensive to keep up with so long term you are better off combining a single bottle with biopellets and hoping they can help colonize the aerobic bacteria. This is essentially the same as running a refugium as you are removing bacteria from your system that consumes these compounds.
The spike of Nitrates or Nitrites can be caused by dirty tank especially within the gravel . The good bacteria cant keep up with the feeding volume. I have learned from 30 years in the hobby that the culprit is always in the gravel or sand. So the less gravel & sand you have the easier to siphon out debris. Siphon the debris and then do a water change using Nature's Ocean Nutri-SeaWater Natural Live the high concentration of live bacteria will settle your tank quickly and allow you to begin a better cleaning regiment. Also watch what your feeding & volume
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