Lake Water Nitrates

  • #1
Decided to finally test the nitrates at the local lake where I fish. This is no small pond, its a 200 + acre lake complete with bass, catfish, bluegill and the other small fish and tons and tons of plants. Its got shallow parts along with some deep water in the middle (12ft or more)

Here were the results, 0 Nitrates.... I was suprised, I guess nature has ways of absorbing nitrates, and any nitrates at all are bad for our fish, tho I'm not gonna worry about anything below 20


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  • #2
I was thinking of doing the same. Honestly, I’m more curious about the ammonia and nitrites. I don’t believe aquariums are a very good representation of how natural water bodies function. Still bodies of water might not use aerobic bacteria, but instead rely more on algae and aquatic plants.
  • Thread Starter
  • #3
I would highly doubt there are any ammonia or nitrites, and the fact that there is 0 nitrates at that lake is because its covered in algae, duckweeds, cattails, hornwort, underwater along the shore everywhere there are plants absorbing the nitrates.
  • #4
  • #5
Since a lake does not have a filter, a lake is not cycled. And since it is not cycled, there is no ammonia being converted into nitrites, and then no nitrites being converted into nitrates.

So what happens to the ammonia? Well, first of all, the stocking density most likely isn't that high so the ratio of ammonia to water is probably rather low. But I would assume any ammonia that is released into the water would be food for plants and algae as mentioned above.
  • Thread Starter
  • #6
jdhef, surely there is bacteria everywhere, on rocks, where the waves splash up, and surely there is ammonia released by dying fish, and other creatures that live in or die and go to the bathroom in the lake.
This particular lake, has geese, ducks, and a dog park upstream. There has to be nitrifying bacteria, in fact you can smell it. It does not rain enough around here for that to be the only source of fresh water, the amount of plants that live in this lake suggest there are abundant nitrates and they are all being consumed, algae, duckweed, hornwort, cattail plants everywhere.

I think you are not correct.

This is a lake in the middle of town. A 230 acre lake, with bluegill, Largemouth black bass, and Channel catfish. There are dead bluegill all along the sandy dam. There are ammonia sources and rocks for bacteria everywhere. The fact that the plants thrive here suggest that there are abundant ammonia being converted to nitrates by bacteria.
  • #7
Well I have to disagree with you on that. Why do you need a filter in a tank at all if enough bacteria will grow on all the surfaces in the tank to process the ammonia? Also keep in mind, plants take up ammonia before they will take up nitrites or nitrates.

BTW, your nose can differentiate between the bacteria that converts ammonia and nitrites for all the other possible bacteria's that may be in that lake?
  • Thread Starter
  • #8
I imagine there is enough dead fish (bluegills) and Duck/goose pee to produce ammonia. There are thousands of smaller fish, reptiles like frogs, ect ect.
All of those have to produce ammonia.
I guess the point I was trying to make is just, WOW plants are really good for an aquarium, and nature.
We can agree to disagree, the only way to find out would be to take some bacteria samples and see if any nitrifying bacteria outgrow the other kinds.....
Never been so happy with my fish (and my fish happy with me) since I crammed a bunch of hornwort into their tanks. The water in some tanks is completely green, but I have no ammonia or nitrates no matter how much I feed, and with guppies, that's a good amount 3 times a day. Its amazing what aquatic plants can do if you have enough of them. And its amazing how they take care of lakes in nature too. **** some people have no airstone or filter, they just throw a bunch of plants and maybe some gravel in the bottom and after awhile the water if fine for fish. Pretty neat stuff that ive learned lately. I use to be a skeptic about aquarium plants because they die easily in my hard water, and they are expensive. But the ones I have now are free, from nature. And working great. Fry everywhere.

I never really knew that plants absorb ammonia, but lately I have been hearing that from a few people. Its not very much, and I assume that Nitrates= Nitrogen the main ingredient in plant fertilizer, is what they absorb the most of ?
  • #9
Lake substrate is full of nitrifying bacteria and deeper sediments are full of denitrifying bacteria that turn nitrates to n gas. Healthy Lakes usually don’t have enough plant life to do the heavy lifting- but they do suck up ammonia and other inorganic N. But bacteria are way more efficient. We need flow in filters only because aquariums are stocked much higher than any lake. So must keep alive an extra high load of bacteria. Wetlands are protected habitats because the system is so good at naturally cleaning water.

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