Plants And Nitrates (Again)

[Kaidonni]

I posted a while back inquiring as to whether plants use nitrates present in the water. Satisfied with my answer, I decided that I need plenty of plants around for my fish as part of the system in the tank (it might not solve all nitrates, but it is hopefully going to be a help in the future). Now...how do they take up the nitrates, though? Not all plants from my lfs have roots (in fact, the ones that do have a massive bundle of them most the time...makes them very hard to plant), and plants also break apart (not as in little leaves or anything, but they break apart low down on the stem). Do they still use nitrates up, or must they take them in through roots and nothing else? I'd remove some of the floating plants, but unless they are well on their way to dying (and they still look green enough), is it wise? Do they still use up some nitrates? This is aside from the fact it might make the tank look a lot barer if I just go removing all plants that have broken off from the stem (and sometimes it feels like all plants have it in for me)...

 

[Mikaila31]

They absorb it through leaves and roots. Some plants like swords and crypts are more heavier root feeders, hence their large root structures. Stem plants like H. polysperma conduct more nutrient uptake through the leaves, which is why they have long stringy roots which are designed to simply anchor them. With these plants nutrients are absorbed through the stoma. These are very small openings in the leaf that allow the transfer of nutrients and wastes in and out of the leaf. Nutrients are absorbed and taken in by the cells, who break them down to use as energy for growing. Just because its a plant doesn't mean its going to absorb a nitrate. If its dying it will be doing the opposite. If its managing to stay alive then is absorbing a little, but probably nothing noticeable. The faster it grows the more it will absorb do to the greater demand.

You seem very concerned about nitrates. When IMO they are one of the last things you should worry about. I planted my tanks, because I wanted plants. And honestly according to my test kits(however accurate they may be) nitrates have gone up considerably in one of my high tech planted tanks. It is seriously a jungle in there. I stopped dosing any nitrates(KNO3) a long time ago. The tank reads double my tap water, which has 20ppm of nitrates in it. This does not bother me really. Algae is minimal, my GBR even spawnd in the tank once. Though the nitrates or my hard water kill all but the hardiest of eggs .

 

[nmonks]

I agree with this wholeheartedly. Nitrate can be a factor behind algae problems, but only alongside other triggering factors like poor water circulation, lack of healthy fast-growing plants, and direct sunlight. But in a healthy aquarium nitrate isn't especially problematic. It's more likely to stress nitrate-sensitive fish (e.g., mollies and cichlids) and lead to disease than anything else. I don't even bother to monitor nitrate. Just do sensible water changes, moderate the amount of food you're adding, and choose the right plants for your system to ensure the tank is "balanced" in a general sort of way. Do that, and algae is essentially a non-problem, and nothing a few nerite snails can't take care of.

Cheers, Neale

You seem very concerned about nitrates. When IMO they are one of the last things you should worry about.

 

[Kaidonni]

Thank you for the replies.

I've had nitrate problems recently, and I'm on my way to getting them under control once more, so plants are a big issue for me. If they take nitrates up, then they can only help. It's just I was wondering about those plants that always seem to have it in for you, the ones that almost always break off from the stem before the day is over.

Mind you, I just did a test on the nitrates, and there is a noticeable decrease in their levels. I'd hazard 10-20ppm, the test tube definitely didn't look as dark purple as last time. But I do worry about this kind of thing, because I obsess a lot (unhealthily...I have OCD).

Algae has never been a problem for me, not for a long time (and I don't have any snails at all, haven't had any for years). The only algae in the tank is that which has built up on the rock and castle over almost 7 years now, and on some of the older plants (some plants just never seem to die! Will they make up their mind?).

 

[nmonks]

I've had nitrate problems recently,

Meaning what? A nitrate problem is anything over 50 mg/l, or over 20 mg/l if you're keeping sensitive species. If this is the issue, then plants are neither here nor there. These high levels of nitrate come with the tap water (in which case use RO or rainwater, with appropriate buffering salts added) or control the amount of food you're adding to the tank (which is usually a problem in overstocked tanks). If these aren't the issues here, and nitrate is below 50 or 20 mg/l, then forget about nitrate.

If they take nitrates up, then they can only help.

Plants are more or less pointless in terms of nitrate control. Yes, fast-growing species will consume some, but not enough to offset a genuinely high level of nitrate. If your tap water contains 50 mg/l nitrate, a clump of Indian fern or a few pots of Hygrophila will have little to no impact.

It's just I was wondering about those plants that always seem to have it in for you, the ones that almost always break off from the stem before the day is over.

Plants usually fragment if [a] they're too leggy, implying etiolation, i.e., insufficient light; or you're using brittle plants in areas of strong water flow, for example a water lily in front of a powerhead. Either way, choose plants appropriate to your tank.

Mind you, I just did a test on the nitrates, and there is a noticeable decrease in their levels. I'd hazard 10-20ppm,

Not enough to worry about unless you're keeping nitrate-sensitive fish, classically thing like Tanganyikan cichlids or mollies in fresh rather than brackish water conditions.

Cheers, Neale

 

[Mikaila31]

Yeah your tank is fine. IMO you should just throw the nitrate test kit away. When I use to dose KNO3 on my tank, nitrate would read 60ppm and my GB rams were not bothered by it at all. I stopped testing nitrates a long time ago. Once a tank is stable you really don't need to test is much at all. Nitrate tests are very unreliable too, so take that 10-20ppm as a very general estimate.

 

[RadaR]

Yeah your tank is fine. IMO you should just throw the nitrate test kit away. When I use to dose KNO3 on my tank, nitrate would read 60ppm and my GB rams were not bothered by it at all. I stopped testing nitrates a long time ago. Once a tank is stable you really don't need to test is much at all. Nitrate tests are very unreliable too, so take that 10-20ppm as a very general estimate.

Indeed.
The only fish that have shown to be sensitive to the inorganic nitrates we use are trout and Salmon. You're not going to keep them, so don't worry about the nitrate. Throw the test kits away.
Plus, nitrates will never trigger algae growth or bloom.