Live Bacteria

Hi Col, I've been following your thread in the scientific section of 'another forum'  I'm essjay on there. To be totally honest with you, I haven't read it recently with all the problems with google, I've almost given up trying to get on that site.

My understanding is that a nitrate of zero is unusual in a freshwater tank, though it is something marine tank keepers strive for - though not being into marine tanks, I'm not 100% sure that's correct.
In a freshwater tank with a mature filter, nitrate is constantly being produced. Plants will remove it, but you have to have a lot of plants to remove all of it. I think what the comment about zero nitrate being rare and something is about to crash means that if the nitrate is zero, it must not be being made therefore something is wrong nearer the beginning of the nitrogen cycle - maybe all the ammonia or nitrite eaters have died.
I did wonder what "exceptionally clean" means - even if every scrap of waste is removed, nitrate would still be produced so they can't have meant that. I suppose if you did very regular, very large water changes with zero nitrate water it would be possible to keep the tank at zero, but that would be a lot of hard work.

I see from the rival site that you have zero tap nitrate and are heavily planted, so in theory for you a tank nitrate of zero is possible. I'm not very good with plants (on the old Thinkfish forum I was famous for being able to kill duckweed  ) so I'm not sure what the implications of zero nitrate are for plants.
If you are worried about the implications of your tank nitrate ("something is about to crash") then checking your ammonia and nitrite on a regular, ie daily, basis should reassure you that if something is going wrong you'll catch it straight away. As for the plants needing nitrate, I'll have to leave that for someone more green fingered to answer.

One thing I will say - my son worked for several years for a water testing company and he is highly amused at us trying to accurately measure nitrate with a home testing kit. The company he worked for used very expensive lab equipment to measure nitrate. He reckoned our kits are incapable of giving a result anywhere near accurate.

Hi Col,

If you have very low nitrates in your tap water, I would suggest that this might be why you are having problems with live plants.

I have quite a heavily planted tank, and every time I have measured my tap water, it has always had <5ppm nitrates. Not zero, but definitely not as pink as the lowest reading on my test set (which is a liquid one).

I was really struggling with my plants, including things like amazon swords which are supposed to be good starter plants. After doing quite a bit of research and some long conversations with Natalia on the old board, I started adding nitrate to my tank at water change. And it makes an enormous difference. There is a photo of my tank in the gallery, so you can see how healthy the plants now look. It does feel very strange to add nitrate when most people do water changes to remove nitrates!

I think that if you have low nitrates in the tap water, you would probably need a heavily stocked tank to go with a heavily planted tank to avoid having to add nitrates. If you think about garden plant fertilisers being PKN (potassium, phosphate and nitrogen), it makes sense that you need these in the right proportions for aquarium plants to thrive.

Apologies if you weren't looking for a plant answer to this post! 

Zero nitrate in rainwater isn't surprising as the main source of nitrate in the water supply comes from run-off from farmland washing away the fertiliser.

The reason for two pH tests in the test kit is that the reagants they use are sensitive to different ranges of pH.  You should choose the one that comes out more central in its range.

By the way don't confuse pH, a measure of the acidity or alkalinity of the water with hardness or softness.  They are usually related, but note the terms usually and related.  If you wish to measure the hardness of your water, there are tests available to do so, but API don't include one in their master test kits.

Thanks again for the replies.  This water thing sure is interesting, I heard about rainwater collecting pollutants but never thought how much or how serious it could be.

I'm not arguing just discussing, but how do small ponds or even garden ponds cope after a heavy rainfall especially those close to motorways or near industrial areas, does the water already in the pond neutralise it or something?

So now the use of rainwater is out, I was thinking it was more pure than the tap water but it seems I'm wrong.

I have seen test kits for things like Phosphates and other minerals but never bothered with them, in one way I'm afraid to start looking because I would get bogged down with even more things to worry about, I am trying not to add chemicals as much as possible that is why I looked at rainwater instead of the chemically treated tap water but it looks like I will have to revert back to it.

I also think knowing the plants is like knowing the fish.  I have gone in the fish shop, looked at plants and thought, 'Oh they look nice' but after a week they loose their leaves or just slowly die off.
They may for all I know be delicate and only like a certain type of water, I've read posts where people have given up on plants and go for plastic.
Some of the reasons are as you mentioned, some put them in the wrong type of substrate, or near fast flowing water and any other reasons.

We learn eventually or from research what fish are compatible with each or or certain types of water but a lot never bother to research the plants, and I will admit I am/have been guilty of it myself.

I agree with both those comments. And have to admit, that I put as much effort into looking after the plants in my tank as I do the fish. Which also means that I don't buy anything without having first researched it, so I know whether it is compatible with what I already have. Soft water, low light, hardness etc

There are also other more in depth topics regarding plant compatibility. There is the (often disputed) idea that some plants give off chemicals that affect the growth of other plants. The most significant incompatible combination for beginners' plants is cryptocornes and amazon swords. I can't remember which way round it is, but one stops the other growing. And, I'm sorry, but I also can't remember the term for this phenomenon.

I actually have both in my tank, and they now grow quite successfully together. To the extent that I am starting to uproot baby crypts because they are spreading so prolifically. So far the amazon swords haven't been affected by being surrounded by crypts!

... There is the (often disputed) idea that some plants give off chemicals that affect the growth of other plants. The most significant incompatible combination for beginners' plants is cryptocornes and amazon swords. I can't remember which way round it is, but one stops the other growing. And, I'm sorry, but I also can't remember the term for this phenomenon.

The term is allelopathy.  It is usually mentioned in respect of algae control.  I hadn't heard about the example you gave but...

Quick biochemistry lesson 

Proteins are made up of chains of thousands of amino acids. Amino acids contain nitrogen, general formula is NH₂.CHR.COOH where R is a side group; it's the exact nature of R that makes the various amino acids different from each other. When living things metabolise proteins, they turn them into CO₂, H₂O and a nitrogenous waste. The exact nitrogenous waste depends on the animal. Mammals turn it into urea, which we dissolve in water as urine. Birds make uric acid which they excrete as a solid (birds only 'poo' they don't 'wee'; thank goodness, bird droppings are bad enough without them dropping liquid on us as well). Animals like fish which live in water can make the simplest nitrogenous waste, ammonia. It takes less energy to make and it can be removed from the body straight from the gills. Other aquarium creature like shrimps and snails also make ammonia as their waste.

But proteins also get turned into simpler nitrogenous compounds when they decompose. Fish food contains protein, and micro-organisms in the water turn this protein into ammonia, amongst other things. This is why fishfood can be used for cycling, and to keep a cycled filter alive if there are no fish in the tank. If you put fishfood in a tank it'll end up as ammonia whether it is processed by fish or by micro-organisms. Another favourite for cycling is dead prawns, the kind you eat. This does end up very smelly and the prawns go slimy which is why it's recommended to put them in a mesh bag like the foot of a pair of tights - makes it easier to remove the slime.


The only reason that ammonia is prefered for fishless cycling is that you can measure the exact amount of ammonia you are adding. With fish food or prawns, because they have to decompose you don't know exactly how much ammonia is going into the water. So you don't know if you have grown enough bacteria to support the addition of you all your proposed fish at the end of the cycle.

There is that. I'm not sure I'd want to be removing disgusting, half decompsed fish food or, even worse, prawns on a regular basis.



Though to play devil's advocate, there is a school of thought that using fish food grows all the other micro-organisms a mature tank needs faster than ammonia solution 

Though to play devil's advocate, there is a school of thought that using fish food grows all the other micro-organisms a mature tank needs faster than ammonia solution

  Now there's something I hadn't thought of.  Learn something new every day here.