High nitrates

[BFResende]

Hey!!!

I finished the cycle about two weeks ago, and my nitrates keep rising.

I have a skimmer, activated carbon, Purigen, and bio cubes. I don't know where all these nitrates are coming from because they're increasing by 10ppm per day.

I already have fish, but the nitrates were rising at this rate even before adding them.

During the cycle, I used Fishless Fuel and Fluval Cycle. Right now, my nitrates are around 60ppm, and I did a 50% water change two days ago.

My phosphates are already at 0.01 due to the partial water changes I've done to try to combat the nitrates.

My KH is at 7.2, salinity at 33.4, and temperature at 25.5, all of which are stable.

Can someone help me understand what's going on?

I can't seem to stop this exponential increase in nitrates.

 

[Mr. Mojo Rising]

Howl long has water been in the tank? What size of tank?

Have you done any water changes? Water changes is the best way to reduce nitrates.

Nitrates are rising is either a test error, or else you are adding something to the water. What kind of test kit do you use, and are you adding something to the water?

Need more info to help you.

 

[BFResende]

It's a Fluval Evo 13.5. The water has been in the tank for just over a month. I'm not adding anything to the tank right now.

Yes, I have been doing water changes, which is why the nitrates are at 60ppm; otherwise, they would have exceeded 100ppm. My phosphate is already at 0.01, so I'm hesitant to do more water changes.

I'm using Hanna tests and I'm already on my second box of reagents, so there’s no mistake.

 

[Mr. Mojo Rising]

How big water change do you do? A 50% water change will reduce nitrate by 50%. Do you test after the water change to see if nitrate is reduced?

How many fish in the tank, what kind of fish?

Do you have any filter pads in the tank? They often increase nitrates if not changed regularly.

 

[BFResende]

At a certain point in the cycle, I had 20ppm of nitrates, so I did a 50% water change and let it stabilize for 4 days.

When I measured after 4 days, the nitrates were at 55ppm, so I did two more partial water changes of 20%, but I was never able to get them below 30ppm.

However, this week they were at 60ppm, so I did a 50% water change 2 days ago, and they’re already almost back to 60ppm.

The water changes are not helping with the speed at which the nitrates are increasing.

I have two clownfish, one Pictichromis fish, and two corals, one soft and one LPS.

I don't use filter pads.

My activated carbon has been in the aquarium since the beginning. Maybe I should change it, right? The Purigen has been in for a week; I added it to try to combat the nitrates.

 

[Mr. Mojo Rising]

wow thats weird, hope someone has more idea's.

Just so we can cross it off the list, how much do you feed?

Do you have access to another nitrate test to double check the hanna results?

 

[Dipi]

Any chance something died in your tank and went unnoticed?

 

[BFResende]

No, nothing has died... the fish have been in the aquarium for a week.

 

[BFResende]

wow thats weird, hope someone has more idea's.

Just so we can cross it off the list, how much do you feed?

Do you have access to another nitrate test to double check the hanna results?

I've already done other tests (Sera) and the values are the same. I feed Aquaforest Marine S (5 pellets per fish once per day), and they eat everything right away; nothing is left over.

 

[Dipi]

Are you using RODI water for top off and WC?

 

[BFResende]

I'm using RODI water for the top off and saltwater for the water changes.

 

[Dipi]

Did you use dry rocks, live rocks, or rock from an established tank?

 

[BFResende]

Dry rocks!

 

[Dipi]

Weel, it seems that all my hypotheses were mistaken. Perhaps you just don't have enough denitrifying bacteria yet, they take more time to develop compared with nitrifying ones. Hope someone else will shed a light for you

 

[Ben's Pico Reefing]

So something is leaking nutrients back in. Could be carbon if you left in during cycle and dosing. Carbon May be releasing what it has stored up as it breaks down.

Test your rodi water to see if there is ammonia. I say ammonia as nitrates are lower when you do water changes. Also have you tested with TDS meter?

I assume your rocks were dry and not used in any other build prior?

You have 3 fish clown and dottyback that you added and feed 5 each. That's 15 pellets a day so That is quite a bioload especially since I did not see a cleanup crew listed. While skimmer should help, poop/waste is possibly building up and settling somewhere. If you do have a cleanup crew, what do you have? Also have you syphoned the sand when you did the water change?

 

[BFResende]

The carbon has been the same since I built the tank, so it is 1 month old.

Yes, I checked the TDS with Hanna.

Yes, the rocks are brand new.

No, I only feed 10 pellets per day—5 pellets for each clownfish. They are very small pellets from Aquaforest Marine S.

I don’t have a cleanup crew yet.

No, I did not clean the sand because it is already very clean.

 

[Ben's Pico Reefing]

So the only source I see is
A. Detritus(fish waste) is built up somewhere. If this was happening prior then this maybe adding but not the main issue.
B. I would remove the carbon or swap out. See if this resolves during water change. Nitrates will still build but if you have skimmer should be removing.

The sand bed could also still be releasing some of the chemicals used during cycling or the rock. Being dry, it will absorb the water including some chemicals. Are if you used live sand, there is die off happening, Usually not an issue though.

Good news is you have the bacteria you need. I would start with removing carbon and swapping first and then doing water change and monitoring. Change one thing at a time. This way you can isolate and identify easier.

 

[MDAquatics]

I second this, you have to eliminate things. Swap the carbon. THe process of elimination is the way to go here. tackle one thing at a time.

 

[BFResende]

So the only source I see is
A. Detritus(fish waste) is built up somewhere. If this was happening prior then this maybe adding but not the main issue.
B. I would remove the carbon or swap out. See if this resolves during water change. Nitrates will still build but if you have skimmer should be removing.

The sand bed could also still be releasing some of the chemicals used during cycling or the rock. Being dry, it will absorb the water including some chemicals. Are if you used live sand, there is die off happening, Usually not an issue though.

Good news is you have the bacteria you need. I would start with removing carbon and swapping first and then doing water change and monitoring. Change one thing at a time. This way you can isolate and identify easier.

Correct, A is not the main issue.

Great brainstorming! Let’s try replacing the carbon.

 

[BFResende]

One other thing: I'm not sure if my skimmer is tuned correctly.