QT system won’t cycle

[hlem]

System consist of 2x50g and 1x75g as sump. Lots of LR, no fish. No skimmer yet. Do water changes here and there. But nitrate won’t go down at all. It’s been over 2 months.  Started dosing bacteria about 2-3 weeks ago daily but still nothing is changing. NO3 still pretty much in the red. 
 

any idea? 

[phlynamjax]

Is this for coral or fish? How did you cycle? NO3 is really not a concern for fish QT.

[hlem]

It’s qt for fish. But NO3 is really high, like 100+. I don’t think it’s completed cycling. Ammonia is 0, but just can’t get the NO3 down 

[ReefdUp]

Could it be your test kit is off? That's a bit odd. 

 

And I hate to be weird, but is there any chance there's something getting into the tank? Funny - and very true story - I had a friend who had a similar problem. Her tank was struggling and had ridiculous nutrient levels. One day, she discovered that her cat had developed a habit of peeing into the tank rather than the litterbox. I'd say weirder things can happen, but that's pretty weird. 😆

[hlem]

Test kit should be fine. As I’m using the same for my frag system and it’s fine there, I have fish and corals to prove that lol

 

The system is in a room that’s closed off. And I don’t have any other animal or things that would contaminate the system. 

[phlynamjax]

Did you try large water change like 50%+? Did you dose ammonia to cycle? If live rock or cycled media is used, then you don’t really have to cycle your QT.

Edited July 13, 2024 by phlynamjax

[ranger]

Your tank is cycled

Rock alone can after the cycle leave alot of nitrate in your system

A skimmer helps alot

I would add at least a hob

100 is nothing in a fish only but it may climb out of control

  once you add fish

I added a full forty breeder of dirty rock into a 80 gallon

 fish only with a hob skimmer on it the tank got nasty but

 cleared up and cycled with a 40 nitrate level

only fish in it is a molly

 

[DaJMasta]

The nitrogen cycle usually isn't completed in our tanks - it just gets removed through nutrient export.  Ammonia is converted to nitrite which is then converted to nitrate,  unless the nitrate is absorbed by plants or converted into nitrogen gas (an anaerobic process and the reason for deep sand beds back in the day), so unless you're removing it with carbon, a skimmer, or water changes (or similar), nitrate will just accumulate over time.

 

That it was converted to nitrate and isn't still ammonia or nitrite, that's the sign the tank is cycled.

[ranger]

I set up a number of tanks in the 80s with 80 percent of live rock

 and even this amount of rock never handled my nitrate.

Have since then always had a upside down sandbed in every tank.

Works no water changes some tanks add a little vinager your set.