Are high, stable nitrates a concern?

I did a 40%ish water change and tank clean today and then I just recently tested my levels. the results were:
pH- 7.8
nitrite- 0
ammonia- 0.25ppm
nitrate- 40ppm

My tap water is nitrate free. the last time I tested my tank was 11/27 (yes I know that’s almost a month, I’ve been too busy to fool with anything other than throwing them some food. I try to test/change water every week) and my results were exactly the same. I did get my nitrates down to 20ppm by doing some water changes at that time.

so my question is: if my tank is stable at 40ppm should I be concerned? I’ve heard that 40 isn’t deadly but I’ve also heard that it is. It may just be a coincidence but last time my nitrates were 40ppm I had just did a 40%ish water change as well.

EDIT: since 40-80ppm on the API freshwater kit is the same color, I tested with the strip version as well and I’d have to lean more towards 40ppm than 80, but it may be above 40ppm. And these are African cichlids, a 55gal running since March.

 

Do much larger water changes. Problem or not, solved.

 

My Clown Loach tank has had those parameters for the last 25 years and all six have remained healthy-looking with no diseases.

 

EDIT: since 40-80ppm on the API freshwater kit is the same color, I tested with the strip version as well and I’d have to lean more towards 40ppm than 80, but it may be above 40ppm. And these are African cichlids, a 55gal running since March.

Take your test tube (5ml) and add half tank water and half 0 nitrate water. Now run your test. That will split your results in half. If you had 80, it will be 40 when you're done.
IME only doing less than 50% water changes leads to a build up of nitrate. You have to do 50% or more each time, or some kind of small water change with a huge one every once in a while kind of thing.

 

Safe Nitrate Levels

Predicate
All discussion of nitrate need to recognize that a scientist’s 10 ppm of nitrate converts to 40 ppm of nitrate per the hobbyist’s API test kit.

Opinion
Nitrate is a very grey area that is best looked at with a human analogy. Let us equate 40 ppm of nitrate per the API test kit (10 ppm per the scientists’ test kits) health wise with one beer per day in humans.”

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Way too much information to allow posting here on this forum.
read the entire article:

 

Safe Nitrate Levels

Predicate
All discussion of nitrate need to recognize that a scientist’s 10 ppm of nitrate converts to 40 ppm of nitrate per the hobbyist’s API test kit.

This is in line with what the aquatic vet manuals has to say about nitrate as well. Very good elucidation.

 

Safe Nitrate Levels

“LPredicate
All discussion of nitrate need to recognize that a scientist’s 10 ppm of nitrate converts to 40 ppm of nitrate per the hobbyist’s API test kit.

Opinion
Nitrate is a very grey area that is best looked at with a human analogy. Let us equate 40 ppm of nitrate per the API test kit (10 ppm per the scientists’ test kits) health wise with one beer per day in humans.”

I Think this just about gave him the answer. It also helped me understand nitrates a lot more. Thank you