0 Nitrates

[Casey02]

Hi there, I am new to the forum and have started a freshwater aquarium in a Red Sea Max 250. I have changed the lights to LED and taken the skimmer out replacing it with more filter media. I have had the tank running for 6 to 7 weeks. I planted a couple of days after filling and bought 6 danio's after 4 weeks. 

I have bought 5 more danios and some loaches which have been in the tank for a week or so.

I am concerned that when I test everything is at 0, ammonia and the nitrites and nitrates, I really shook up the Nitrate testers and I am still getting a 0 reading.

Is this harmful for the fish in anyway and do you think my tank has cycled?

Thanks

[Fruju]

Hi, welcome to the forum.

I doubt you would have any nitrate readings after 7 weeks with that few fish in it, usually takes a bit longer for you to see any. More fish will of course increase the amount of nitrate that will be present in the system. Plants also extract nitrate, so you do have some removal there. You didn't mention water changes? Water changes are the best way to keep nitrates low and if you have been doing them since the tank has been set up then it's one more reason why you haven't seen nitrates.

Nitrate isn't harmful in small amounts, I would consider anything over 20 ppm detrimental to fish health though. Nitrate can stunt growth and may lead to some health issues in fish, I think lateral line erosion (HLE) is caused by this.

You should mainly be concerned with ammonia and nitrite, if those are zero then great. Nitrate is more of something to keep in check, but is unlikely to outright kill your fish swiftly. Your tank should be cycled in 7 weeks for sure, you can always use stresszyme and stability to supplement the bacteria. Having ceramic or other high surface area media is going to help bacteria establish.

Keep doing water you're doing, keep checking the nitrogen levels, especially when adding new fish.

[Casey02]

Thanks very much, I have done a few water changes and have ceramic and sponges as filter media. Will just keep letting it mature slowly and add more fish in another few weeks.

The fish look happy but I was worried as I know it's normal to have a small amount of Nitrates in the tank.

[Fruju]

No worries, cycling fish tanks is the toughest part of fishkeeping, the rest is easy...everything is relatively straightforward.

Critical things are ammonia and nitrite, that will end your fish quickly. Some signs of ammonia/nitrite poisoning is clamped fins, loss of slime coat and gasping at the surface (ammonia inhibits oxygen transport across the gills).

[nays]

I started a 165l planted freshwater aquarium with a fish-in cycle in January.  I tested daily for ages for the dreaded ammonia spike - it never came.  To this day I've never seen ammonia or nitrite registering, and nitrate only shows up when I add it myself.  Gotta love those plants :-)

[Fruju]

3 hours ago, nays said:

I started a 165l planted freshwater aquarium with a fish-in cycle in January.  I tested daily for ages for the dreaded ammonia spike - it never came.  To this day I've never seen ammonia or nitrite registering, and nitrate only shows up when I add it myself.  Gotta love those plants :-)

To be honest you don't always have to expect to see an ammonia spike, especially in medium to large tanks or tanks with below average stocking earlier on. Using some established media in the filter is also a good way of avoiding ammonia spikes. Plants definitely have a good effect! Hard to quantify though.