Should I add fish to a zero nitrates established aquarium?

[ramtsi]

Specs:
A 72 litre dirted tank with an internal canister and sponge filters.
I'm growing hygrophilia polisperma, alodea, anubia nanas and some java fern
Two 10w lights.

0 ppm on all parameters since I cycled the tank.
I'm using the api master kit, shaking the chemicles vigorously every time I'm testing.

1. Should I even care about the nitrate levels in the water column as long as they aren't high?
2. Does adding fish is a proper solution to the issue? I'm not using a fertilizer.

[Aiken Drum]

How did you cycle the tank?

[ramtsi]

No fish cycle with Dr. Tims amonium chloride solution.
It has been almost a year since I cycled it. During the cycle I had all parameters as expected (amonia, then nitrites and almost 40 ppm nitrates in the end) and only after amonia and nitrites went to zero ppm I started adding fish.

All the fish are healthy and doing well.

[Aiken Drum]

So you havent had any fish in the tank for about a year? Did you continue to dose ammonia during that time?

Edit following added info above.

So you already have fish? Im confused as to what you want advise on. Are you just wanting to add more fish to an already stocked tank? What fish do you already have? How many?

[Aiken Drum]

Are you concerned that zero nitrate is an issue?

While its true that nitrate will be present in most aquariums because the nitrogen cycle turns ammonia into nitrate, this wont always be the case. The first 2 plants you mention are nitrogen hungry plants. They will either be consuming ammonia from the water and getting it before the nitrogen cycle has chance to turn it into nitrate. Or consuming nitrate after the nitrogen cycle has done its thing. Probably the former, maybe a little of both. Either way thats why you are seeing nothing in your water testing.

Is zero nitrate a problem? Depends.

Zero nitrate is the ideal amount for your fish. While they are tolerant of nitrate, zero is the ideal level for them.

As mentioned, plants need nitrogen though. They are getting some from your fish waste but is this enough? Your substrate will also be providing nitrogen to the rooted plants. If your plants show no signs of nutrient deficiency then everything is fine. If there are signs of nutrient deficiency then this may be down to the amount of nitrogen your fish put in the water. A solution to this could be more fish if you have room in your aquarium. Or you could dose an all in one liquid fertiliser that has a good amount of nitrogen in it. Most dont because nitrogen is perceived as being a cause of algae growth.

TL: DR If everything is healthy and happy then leave things be and stop worrying.

[ramtsi]

I have fish in the tank for about a year now. Thank you.