High nitrate on an empty tank?

[AZMSGT]

My 625 has been cycled for a few weeks. Just been waiting to add live stock that is in QT. My nitrates are just going up and up.. I’ve been doing water changes every week since the cycle finished. Yet.. nitrates keep rising.

Using salifert test kits today.
Ammonia is at 0
Nitrites are at <0.1
Nitrates are at approx 75

Last week nitrates were 50
The week prior they were between 25 and 50

The rock in the tank was just plain dead mined rock. I bleach cured it about 3 weeks before I started the tank up on Jul 15.

 

[azank]

How did you cycle it?

 

[jeffchapok]

Are you ghost feeding the tank or have a chunk of fish or shrimp in there decomposing?

 

[ZoWhat]

My 625 has been cycled for a few weeks.

I think we all need to know HOW your tank has been cycled... in detailed description... to address your issues.

 

[AZMSGT]

I cycled it with Dr Tims and Microbactor7. I used 2 shrimp in the beginning but took them out as the cycle was proceeding and it looked like everything was done. I dosed Dr Tim’s Ammonia to see if it would clear up and it took a few days for the Ammonia to go back to zero. At that point I had some things going on and didn’t test water for a week and a half. When I went back to test I found the ammonia was 0 nitrites had come down to the 0.1 mark and the Nitrates were 25. Did a 20% water change. The following week tested and nitrates where in the 25 range again. This is when I started doing regular water changes and watching nitrates.


I had the skimmer off and the filter socks out up until two weeks ago. At that point I put the socks back in more to silence the running water sound. Ive changed the socks once a week since. They are only picking up small debris, a couple hairs and some of the food from the once a week ghost feedings.

I have ghost fed 1 cube a week but I didn’t think that would cause such a nitrate spike even with 20% water changes on an empty system.

After todays nitrate readings I restarted my skimmer.

I had a ICP test done a week ago and it all came back perfect.

I’m still 2 weeks or so from adding fish due to QT delays.

 

[jeffchapok]

I would stop the ghost feeding. There's nothing in there but bacteria to consume it at this point, so everything you add is going to end up as nitrates.

 

[ColdOceanReef]

Stop feeding and let Nitrates take it course. I would do a big water change 75% at the end of nitrates instead of small changes.

 

[W1ngz]

I'm thinking some of your rock wasn't as plain or dead as you thought. There is probably also a lot of decomposing food in there if it got into crevices and started rotting without any crabs even to eat it.

Like others have said, stop feeding, do a big big water change and then see what the nitrates do when left alone. Maybe add a handful of hermits and bumblebee snails to clean out the cracks.

 

[RyanSweet]

Check the water that you’re changing with as well. Sometimes the new saltwater will have nitrates that we don’t think about because it’s “new” and that is causing issues as well.
But as mentioned, stop feeding the tank since there’s nothing on there to consume it.

 

[EmdeReef]

Fwiw it’s pretty common for recently cycled tanks to have high nitrates. It’s really not a cause of concern though.

 

[AZMSGT]

A 75% water change is not in the cards. I have a total of 160g. My biggest container is 40g that I can mix water in.

 

[MabuyaQ]

If the tank is emty (no fish, corals) you could try dosing carbon to put the bacteria in overdrive, even create a slight bloom. Just reduce filtersocks and watch you skimmer.

 

[W1ngz]

Carbon dosing risks bottoming out nitrates and phosphates, encourages bacterial blooms and promotes dinoflagellates. It works, but I don't think it's a good idea here. Better to go after the cause (rock and/or decomposing food) rather than the symptom which is the nitrates.