Does stopping carbon dosing...

[Animal-Chin]

make your nitrates go through the roof?

I used NOPOX for a few months and my nitrates went from 20 to 10 which was fine but I found the bad outweighed the good from using it so I stopped. I read all over the internet that it was ok to just stop.

So I notice some weird action with my coral in the tank and start testing the water. Cal normal, alk fine, no phosphates still and then I test nitrates....80!

I've been reefing for 6 years and have never had nitrates like this!!! I only have 8 fish in a 125 gallon so I'm not over stocked. My feeding routeen hasn't changed.

Does the de nitrifying bacteria dying off cause a huge nitrate spike?

My only other thought is a sea cumber or starfish died under the rock work or something.

[tang daddy]

Is your tank sand or bare bottom, perhaps a lot of detritous in the sump and sand leeching out nitrates over time which has happened with a sand bed, especially if you have a fish that sifts the sand releasing nitrates over time. Perhaps you need a few large water changes to get rid of the build up.

[Animal-Chin]

Sand bed, pretty shallow though and pretty clean. My sump is spotless so its not a sump issue for sure.

My amazement is the speed in which this happened. 2 weeks ago I was worried about a reading of 15, now I'm at 80? Something major is going on, though maybe bacteria dying off could cause this?

[tang daddy]

How long has your tank been up? Any pics of the rock work/tank? Can you confirm if the cuc did actually die?

It is a possibility that your rock is leaching out nitrates... If the bacteria died that could cause a spike but one would think that if that happened then other bacteria strains would thrive equaling out the imbalance.

How old is your tank, do you run bp or carbon dose?

A pic of the display and sump would help.
Also what is your feeding regimen and how much do you feed?
Skimmer size and info on tank specifications and equipment would help aswell.

[Animal-Chin]

How long has your tank been up?

2 years exactly

Any pics of the rock work/tank?

See Attached...

Can you confirm if the cuc did actually die?

Nope but I have a blue star and a tiger tail cucumber that only come out in the middle of the night, one of them may have but I have no idea.

It is a possibility that your rock is leaching out nitrates... If the bacteria died that could cause a spike but one would think that if that happened then other bacteria strains would thrive equaling out the imbalance.

How old is your tank, do you run bp or carbon dose?

I was using NOPOX but stopped and recently set up a biopellet reactor that hasn't kicked in yet. Hopefully it will soon and start reducing.

A pic of the display and sump would help.



Also what is your feeding regimen and how much do you feed?
Skimmer size and info on tank specifications and equipment would help aswell.


Feed frozen food daily, a mix of home made, mysys, krill, the regular frozen stuff all rinsed prior. I have in the sump a sock into a chamber with A SWC skimmer rated for 160 gallons with a phosphate reactor and a biopellet reactor. Sump is totally clean, no ditrutus at all. I do regular 15 gallon water changes every Wednesday.

[tang daddy]

You actually had a tank journal, just saw it now. Tank looks amazing, how are your corals doing with the high nitrate? Lps super happy? How about sps?

Even though you have a low sandbed maybe possible that it could be leeching?

How much rock do you estimate you have?

Your feeding seems ok but if you are putting a lot of food in and some of the food gets missed or not eaten that could definately play a role on the nitrates creeping up. Bp may lower nitrates but only to the extent that it can lower phosphates. Once there is an imbalance you may start to see cyano bacteria.

You may also want to try siporax to lower nitrates, as I've heard it is great results. 15g water changes is better than no waterchanges but if your nitrates are through the roof it may not be any harm to do some larger wc like 80g.
If it's possible.

I haven't measured nitrates in my tank yet but don't have a lot of rock in the display, also only started with a few lbs live and the rest was cooked rock. I will be starting siporax soon for extra filtration to break down the nitrates, I just need to get a hold of a large canister like a fx6 or and ehiem 2250.

I feed my tank heavy 2 times a day as I just added some anthias.

But if it was me I would try a large wc then test the next week to see where I am at, as this seems to be the easiest adjustment to do now.

[Craigdillman]

This is totally normal ,

the carbon dosing that you slowly built up over the period of time built up the extra bacteria that was handling your nitrates semi- effectively as they were still 10 which is high, now all of a sudden you stop dosing the carbon and all that "extra" bacteria goes away. Since you changed nothing else no extra WC or less feedings or more skimming, Your tank goes back to high Nitrates cause the carbon dosing was the "fix" for it or "bandaid" if u will.. Nothing wrong with that lots of tanks (mine included) only are successful cause of healthy carbon doing on a daily basis ( Zeo tanks, Bio pellet, Vodka...) these things need to be tampered on and off slowly or this happens . Im guessing that your nitrates have always been a bit on the high side and when u started carbon dosing it dropped it down to 10-20 level but when u stopped it rebounded ..

2 things you can do to fix it

1) start carbon dosing again , vinegar/vodka is the easiest then to bio pellets then full zoo

2) Reduce input or Increase output ... feed less, skim more , WC more any combo of them to reduce the Nitrates


Tank should be good , i know when i was on holidays and my doser ran out of vinegar and i had 2 weeks left in the vacation , i came home to my nitrates in the 75ppm range when now that are less them .5 on the hanna now

Cheers man and good luck dont stress

[Animal-Chin]

Thanks guys, did 30 gallons and i think the biopellets have kicked in cause im down to 40 now. Never thought i'd say "down to 40" lol.

[tang daddy]

What Craig said is true which is feed less and skim more while using bp or some other sort, a larger wc will only displace the nitrates temporarily but it will slowly creep up again. BP takes awhile to build up before it gets going like a few months. If you can I would do another larger wc like 50% this should in theory cut your nitrates down even further....

[Potatohead]

Correct I would continue carbon dosing for at least another six weeks and then slowly back it down for the next month, unless your nitrate starts to go really low then maybe end it a bit faster and monitor for the next week to make sure the pellets are working.