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High Nitrate Tap Water and KNO3

W

waynest

Seedling
Joined
20 Sep 2008
Messages
11
Hi

My tap water has average 30 ppm nitrate (min 20ppm max 40ppm from 12 monthly tests in 2009), this is from Severn Trent water analysis not hobby test kits

My tank is 450l with 4x54w T5 and CO2, 50% water change every week

A fair few fast gowing stem plants in there.

I dont add KNO3, just pot sulphate, pot phosphate and trace mix.

I am wondering if the tank could consume all the tap nitrates and bottom out towards the end of the week?

Something is not quite right, Rotala Indica has all but died out on me after keeping it for years. But others doing well, no algae problems at all. For what its worth (not much IME) a nitrate test kit reads 30ppm straight after wc and 10ppm just before. Would anyone argue to add KNO3? A slug of it midweek maybe?
 
Hi Wayne
My tap water is 50ppm Nitrate but I still add KN03 with no problems.I have a large plant mass, so its your choice.....
20ppm to 30ppm is the recommended dose so your in that parameter.
I do 80% water changes once a week if i have time..... with no problems to fish.
Regards
hoggie
 
I'm in a similar situation. About 25ppm nitrate (measured using a calibrated nitrate test kit before Mr Barr pipes up ;) ) in the tap water - only dosing KH2PO4, K2SO4 and traces (TPN + Flourish Iron). Mixed results, crypts & vallis growing away well, but Rotala rotundifolia is just sitting there and hardly moving and Pogostemon helferi browning and melting.

I've just started adding 3 doses per week of 5ppm Nitrate from KNO3 starting today to see if that makes any difference. It almost seems like there the nitrate in the tap water has lesser 'value' than that in KNO3 - is there any other chemical that may exist in our tap water that would cause a response from a nitrate test kit but would be of no value to our plants?

Peter
 
Hi,
Unless you can more precisely clarify what "Rotala Indica has all but died out " means, then drawing a correlation between this and nitrate levels is meaningless.

Nitrate starvation has a specific failure mode. It would be characterized by a combination of chlorosis in mature leaves, poor growth and possibly the appearance of nitrate deficient related algae such as BGA. If none of these symptoms are evident then there is only a low probability that the failure you describe is due to nitrate starvation.

You need therefore to more accurately describe the symptoms of the Rotala failure (or provide a photo) in order to perform a more logical diagnosis.

Cheers,
 
Hi
Im no chemist but although we have nitrates in the region from 20/50ppm in our tap water can this nitrate be utilised by plants :?
Im opening a huge can of worms here. :lol:
Is this the same chemical composition that we dose in our aquariums. :?:
Do plants need higher doses of nitrate than we think :?
Is 50ppm minuscule in the big scheme of things :?:
Someone may know the answers.
hoggie
 
hogan53 said:
I'm no chemist but although we have nitrates in the region from 20/50ppm in our tap water can this nitrate be utilised by plants :?
Click to expand...
My gut reaction (I'm a physicist, not a chemist) is that any NO3 ions present should be available to the plants - after all, I suspect that they are mostly derived from all of the ammonium nitrate that our farmers throw on their fields every year. But I'm sure Clive will come back here in a minute and give us an incredible discourse ;)

Peter.
 
The top 1" of the rotala the leaves look healthy, although small. Colour at the tip is yellow-green turning to red a few leaves down.
The next 1 -2" of the stem the leaves look dog rough, black mottled pattern.
Below that, bare stems.

The plant's not in shade, and is in the current from the CO2 diffusor, it should be pushing the lid off the tank.

Thanks all for the replies
 
waynest said:
The top 1" of the rotala the leaves look healthy, although small. Colour at the tip is yellow-green turning to red a few leaves down.
The next 1 -2" of the stem the leaves look dog rough, black mottled pattern.
Below that, bare stems.

The plant's not in shade, and is in the current from the CO2 diffusor, it should be pushing the lid off the tank.
Click to expand...
Hmm, well, as incredible as it seems, these are classic symptoms of poor CO2. So you have a bigger mystery than you thought unfortunately. This could be a result of poor flow distribution. Can you describe your filter outlet arrangement and the position of the diffuser? Is this an in-line diffuser or a ceramic disk mounted on the glass?

Whitebeam said:
...any NO3 ions present should be available to the plants - after all, I suspect that they are mostly derived from all of the ammonium nitrate that our farmers throw on their fields every year.
Click to expand...
Yep, I totally agree with Peter on this. NO3 molecules are NO3 molecules. There is also of course organically derived NO3 from waste, decay and subsequent nitrification.

Cheers,
 
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