Water Parameters - NO3

[MaxM]

Hi All - perhaps someone has experienced the following. I am pretty diligent when it comes to monitoring water parameters and doing water changes (Including cleaning my sponge filters 3 days after vacuuming the tank). I keep my parameters within a healthy range and it rarely goes up above the first signs of concern. Two things, however, are always high. One is the water hardness, but I've learned to live with that being that in my country the water in general is hard and the fish here have adapted to the hardness. Believe it or not, even Discus are sold here and have adapted to the hardness of the water (21 dh).

My problem is NO3. No matter what I do the NO3 is always between 50-100mg. 50% and even 75% water changes never bring it below 50mg. Does anybody no if that is normal in certain parts of the world? Being that it is not as dangerous as NO2 and also being that I do regular water changes should I worry about this at all?

[Andy's Fish Den]

Have you tested your tap water? If you can't get the levels to go down even with water changes, there is a good chance that there is some in your tap water. It's not unheard of to have nitrate in tap water.

[MaxM]

I've tested the tap water in the past, but decided to test again today. NO2 is slightly high at 2mg, but NO3 is at 25mg (within green range). It could be that in the tank the NO2 is converting to NO3 and raising it to 50mg.

The question is whether the fish here are used to slightly higher NO3 then in America?

[Coronal Mass Ejection Carl]

Do you have any waste accumulation in your filters or substrate? Are you feeding heavily?

Nitrate is basically non-toxic but I would still try to get to the bottom of things.

Dissolved organic carbon is much more toxic than nitrate and we don't test for it. Nitrate levels can kind of be used as a proxy for DOC levels as the two are somewhat correlated (unless you change water but don't clean your substrate or filter).

[Hobbit]

I’d be curious what water parameters your local fish store has. If it’s a regional thing they may have experience with whether any long term effects crop up.