I keep Malawians and Tanganyikans and have no problems growing plants in their tanks (anubias, bolbitis, java fern, etc.). But that is not the issue. Obviously if you have high nitrates in your tap water, water changes are not going to reduce the nitrate level in the tank below the nitrate level of the tap water. So what is the point of testing for nitrates if your tap water has high nitrate levels? The goal would be to reduce the nitrate level in the tank by adding aquatic plants, or terrestrial plants growing hydroponically in the tank, or using a nitrate reactor or reductor. Finally as to water changes, they should be done on a regular basis. Heavily stocked tanks should have their population thinned out. But if you must have a heavily stocked tank, then you must do more frequent water changes. Don't need to test for nitrates to tell you that you need a water change. Happy fishkeeping.Sorry, but that just not true. Many local water supplies have high levels of nitrates. I too have kept fish for over 30 years and having lived in 4 different states i can tell you all water supplies are not created equal. The plant idea is great, but would have little effect in my mbuna setup which sits at a ph of about 8.3. Very little plant life in Lake Malawi.....
Plus testing for nitrates will give you an idea of how often you should do regular water changes depending on how you stock. Heavy stockers need more frequent changes than light stockers and a good test kit will tell you wether weekly changes are enough without guessing. And for some of us who breed nitrate sensitive fish such as loricariids, guessing and hoping for the best isn't good enough
I keep Malawians and Tanganyikans and have no problems growing plants in their tanks (anubias, bolbitis, java fern, etc.). But that is not the issue. Obviously if you have high nitrates in your tap water, water changes are not going to reduce the nitrate level in the tank below the nitrate level of the tap water. So what is the point of testing for nitrates if your tap water has high nitrate levels? The goal would be to reduce the nitrate level in the tank by adding aquatic plants, or terrestrial plants growing hydroponically in the tank, or using a nitrate reactor or reductor. Finally as to water changes, they should be done on a regular basis. Heavily stocked tanks should have their population thinned out. But if you must have a heavily stocked tank, then you must do more frequent water changes. Don't need to test for nitrates to tell you that you need a water change. Happy fishkeeping.
Having read some of the original poster's previous posts, he is concerned about elevated nitrate levels due to the fish he keeps. He is not trying to breed fish that require a specific nitrate level. Just trying to help out by suggesting ways to reduce his nitrates.