# Low KH, high TDS ?



## eminor (22 Dec 2021)

Hello, since two months i swapped from 100% tap water to 75% rain water (15 ppm) and 20-25% tap water ( 240 ppm, GH 17, KH 11), i change 50% of water every week, how is that possible the tds show me 300 ppm (calibrated tds meter)  ?

i have no rock  in the tank, just plants and sand

I dose EI (magnesium, no calcium)  but it seems insanely high for soft water, where does all of that come from ? thx


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## MichaelJ (22 Dec 2021)

eminor said:


> Hello, since two months i swapped from 100% tap water to 75% rain water (15 ppm) and 20-25% tap water ( 240 ppm, GH 17, KH 11), i change 50% of water every week, how is that possible the tds show me 300 ppm (calibrated tds meter)  ?
> 
> I dose EI (magnesium, no calcium)  but it seems insanely high for soft water, where does all of that come from ? thx


Yes for weekly 50% WCs given your WC water ppm's,  300 sounds really high... the WC water alone should be around ~70 ppm... even with high EI (NPK with Mg) that shouldn't add more than ~60 ppm... What are you dosing exactly and when, are you adding anything else to tweak other water parameters?

Cheers,
Michael


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## eminor (22 Dec 2021)

MichaelJ said:


> Yes for weekly 50% WCs given your WC water ppm's,  300 sounds really high... the WC water alone should be around ~70 ppm... even with high EI (NPK with Mg) that shouldn't add more than ~60 ppm... What are you dosing exactly and when, are you adding anything else to tweak other water parameters?
> 
> Cheers,
> Michael


KNO3 15 ppm
K2SO4 20 ppm
PO4 2 ppm
MG 10 ppm
micro iron : 1 ppm

macro once a week, micro three ( total 1ppm iron)

nothing, just injecting CO2.

300 ppm could explain why some soft water plant struggle ? i also use 2hr aquarist method with turkey blaster to clean my soil every week, is it bad ? i doubt this it the cause, i take out organic waste that came out the soil i don't go deep (0.5 cm)


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## John q (22 Dec 2021)

S


eminor said:


> how is that possible the tds show me 300 ppm (calibrated tds meter) ?


Seems perfectly possible to me. 

I use tap water that's 75ppm, dose ¾ ei (ish) and do 50% weekly water changes. Tds after water change is around 180, before water change is around 290. 

We forget about "other" organics in our tank that we can't control, fish waste or plant waste e.t.c... all these add tds. 
Is the 300ppm tds causing issues.  Or are you thinking your issues are related to "high" tds readings?


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## eminor (22 Dec 2021)

John q said:


> S
> 
> Seems perfectly possible to me.
> 
> ...


this tank have zero fish so maybe plants but i had tank with more plants that had way lower tds, i'm thinking that the high tds cause some trouble with myriophyllum species, but i'm always wrong in this hobby 😅


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## John q (22 Dec 2021)

eminor said:


> i'm thinking that the high tds cause some trouble with myriophyllum species


I'm no expert in this but suspect the plants don't  care much about tds readings. Possibly the plants aren't happy for other reasons and are  contributing to the tds readings you're getting.


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## MichaelJ (22 Dec 2021)

John q said:


> S
> 
> Seems perfectly possible to me.
> 
> I use tap water that's 75ppm, dose ¾ ei (ish) and do 50% weekly water changes. Tds after water change is around 180, before water change is around 290.


Hi John, I can see that in a high energy tank - with high plant metabolism etc. - but not in a low energy tank - so something is totally amiss. My TDS swing during the week is 225-230 ppm after WC to 240-245 ppm before weekly WC.



John q said:


> We forget about "other" organics in our tank that we can't control, fish waste or plant waste e.t.c... all these add tds.


The 50% WC is supposed to take care of that and should be sufficient - but might not be in this case if there is a lot of waste piling up.

Cheers,
Michael


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## MichaelJ (22 Dec 2021)

Oh, overlooked that this is an injected tank. Sorry.   Sooo its likely what @john p said... Still quite a swing IMHO.


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## John q (22 Dec 2021)

eminor said:


> just injecting CO2





MichaelJ said:


> but not in a low energy tank -


Sorry, I assumed this was a high tech tank.


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## MichaelJ (22 Dec 2021)

John q said:


> Sorry, I assumed this was a high tech tank.


My bad.


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## sparkyweasel (22 Dec 2021)

eminor said:


> ( 240 ppm, GH 17, KH 11),


17GH alone will give you 304ppm. If you measured 240ppm your meter could be inaccurate.


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## MichaelJ (22 Dec 2021)

sparkyweasel said:


> 17GH alone will give you 304ppm. If you measured 240ppm your meter could be inaccurate.


Thats true and very likely if the device is highly nonlinear... but it also depends on the internal conversion factor from microsiemens to TDS - as all these TDS meters internally measures us/cm. Some use 0.64 some 0.5... With some of Hannas models you can choose 


Cheers,
Michael


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## erwin123 (23 Dec 2021)

rather than a single measurement of TDS, Eminor should do a TDS profile, i.e. measure

(1) The average TDS of the rainwater+tapwater mix added to the tank
(2) The tank TDS before WC
(3) Daily TDS readings after WC

More data points will enable a better of assessment whether there is something odd going on (EI solution mixed wrongly?) , or the TDS meter is not accurate, etc.

I used TDS meter and Nitrate test to doublecheck whether my osmocote pellets are leaking nutrients into the water column -so far so good. I just noticed that Eminor also asked about Osmocote in a separate thread: osmocote, how much ?   - may have to consider whether your root ferts are leaking into the water column...


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## MichaelJ (23 Dec 2021)

eminor said:


> KNO3 15 ppm
> K2SO4 20 ppm
> PO4 2 ppm
> MG 10 ppm
> micro iron : 1 ppm


Got it, but what compound are you actually mixing and in what quantities vs. water volume etc.?

You should try do the "TDS profiling" as suggested by @erwin123 above.

Cheers,
Michael


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## eminor (23 Dec 2021)

MichaelJ said:


> Got it, but what compound are you actually mixing and in what quantities vs. water volume etc.?
> 
> You should try do the "TDS profiling" as suggested by @erwin123 above.
> 
> ...


i mesured with tds each one and it's correct

KNO3 :

500 ml -> 30 ml = 21.5 grams
NO3 target : 15 ppm
N: 3.3
K: 9.4
--------------------------------------

KHPO4 :

500 ml -> 30 ml = 2.44 grams

PO4 target : 2
P : 0.6
K : 0.8
--------------------------------------

K2S04 :

500 ml -> 30 ml = 18.8 grams

K : 10 ppm -> target : 20 ppm, KNO3 9.4 + 10 = 19.4 ppm
S : 4.1
--------------------------------------

Mg

1000 ml -> 30 ml = 200 grams

Mg target ->    10 ppm
S    13.19
dGH    2.31
--------------------------------------

Trace

400 ml -> 20 ml = 12.1 grams

Fe target -> 1 ppm
B    0.10
Mn    0.18
Mo    0.02
Zn    0.12
Cu    0.02


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## eminor (23 Dec 2021)

erwin123 said:


> rather than a single measurement of TDS, Eminor should do a TDS profile, i.e. measure
> 
> (1) The average TDS of the rainwater+tapwater mix added to the tank
> (2) The tank TDS before WC
> ...


i'll do, today i changed 90% of water to do a restart, 25 liters rain water (20 ppm) and 10 liters tap water (240 ppm), tds has been calibrated with HM digital calibration solution 342 ppm

day 1 :
before WC : 290
after without EI : 120
after dosing EI : ~180


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## erwin123 (23 Dec 2021)

eminor said:


> i'll do, today i changed 90% of water to do a restart, 25 liters rain water (20 ppm) and 10 liters tap water (240 ppm), tds has been calibrated with HM digital calibration solution 342 ppm
> 
> day 1 :
> before WC : 290
> ...



Noted that there is a 60ppm increase with EI dosing- this is your weekly EI macro dose? So there will be one more weekly micro dose and that will be the 'final' ppm due to added ferts? 
I just did a water change yesterday, so I can also compare my TDS profile

day1:
after WC before dosing - *120-125 *(can't remember exactly)
after dosing: didn't record

day 2
after dosing: *130*

Basically my expectation is for ppm to increase by about 10ppm a day.


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## eminor (23 Dec 2021)

erwin123 said:


> Noted that there is a 60ppm increase with EI dosing- this is your weekly EI macro dose? So there will be one more weekly micro dose and that will be the 'final' ppm due to added ferts?
> I just did a water change yesterday, so I can also compare my TDS profile
> 
> day1:
> ...


i dosed all macro for the week yes, micro 3 times a week so + 1 ppm, i start dosing micro tomorrow

i waited 30 min now the tds show 194 ppm, light still closed, co2 too, i think that's because the ferts are now everywere in the tank, still where does it goes from 120 to 194

should be + 47 with EI not so much ?


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## dw1305 (23 Dec 2021)

Hi all, 


MichaelJ said:


> Thats true and very likely if the device is highly nonlinear..


The <"ions in solution vs Conductivity"> relationship is <"pretty linear">, all the way up to sea water.  

cheers Darrel


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## MichaelJ (23 Dec 2021)

eminor said:


> i'll do, today i changed 90% of water to do a restart, 25 liters rain water (20 ppm) and 10 liters tap water (240 ppm), tds has been calibrated with HM digital calibration solution 342 ppm
> 
> day 1 :
> before WC : 290
> ...



Well, that seems to add up (provided the fert dosing is what's stated above). I do no use CO2 so I dont have any practical experience with how much the TDS typically will go up day by day in an injected tank... but it now seems plausible, considering @erwin123 and @John q statements above - that is, going from 180 to 300 (120/7) = 17 ppm per day - which still seems quite high considering that your front loading all the ferts.... Maybe your adding too much CO2...The CO2 experts here can help you sort that out.

Cheers,
Michael


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## erwin123 (24 Dec 2021)

My TDS will be slightly off because I had to change 5 litres (half a bucket of water) to do some cleaning.

after WC before dosing - *120-125 *(can't remember exactly)
after dosing: didn't record

day 2
after dosing: *130*

day 3  (changed 5 litres of water before measruement)
before dosing *125*
after dosing *130*

My meter showing a 5pm change looks reasonably accurate give or take a few ppm because my dosing is roughly 3.5ppm based on my calculations.
But I am surprised that TDS didn't change that much from the day before. Anyway, I have the whole week to check.


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## eminor (24 Dec 2021)

Day 2 : 200 ppm before light and co2 start

it seems okay so far right ?


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## erwin123 (24 Dec 2021)

eminor said:


> Day 2 : 200 ppm before light and co2 start
> 
> it seems okay so far right ?



If you did not dose ferts on day 2 any particular reason for 20ppm increase in 1 day?

Day 1: 180ppm
Day 2: 200ppm (no dosing?)


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## eminor (24 Dec 2021)

erwin123 said:


> If you did not dose ferts on day 2 any particular reason for 20ppm increase in 1 day?
> 
> Day 1: 180ppm
> Day 2: 200ppm (no dosing?)


day 2, just micro which should be less than 1 ppm, the 20 ppm could that be CO2 ? maybe not because it will go out with light off ?

sometimes i put rain water in because it's open top so evaporation, could be that too, rain water is 20 ppm but i only add a bit it can't explain the 20 ppm jump


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## erwin123 (24 Dec 2021)

eminor said:


> day 2, just micro which should be less than 1 ppm, the 20 ppm could that be CO2 ? maybe not because it will go out with light off ?
> 
> sometimes i put rain water in because it's open top so evaporation, could be that too, rain water is 20 ppm but i only add a bit it can't explain the 20 ppm jump



If the 20ppm is unexplained it might be a problem - maybe not the ppm itself, but the substance that is causing this increased 20ppm reading, or alternatively, the 20ppm is from something harmless, in which case it is not a problem. But as you pointed out, it can't be from your fertiliser dosing.

If you top up 180ppm water in your tank with 20ppm water, the ppm of the water should drop, not increase.


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## jaypeecee (24 Dec 2021)

Hi Folks,

I just quickly scanned this thread - so, ignore me if this point has already been made - is the dissolved CO2 contributing to the electrical conductivity? If so, this would show up on a 'TDS' meter. Just a thought.

JPC


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## eminor (24 Dec 2021)

erwin123 said:


> If the 20ppm is unexplained it might be a problem - maybe not the ppm itself, but the substance that is causing this increased 20ppm reading, or alternatively, the 20ppm is from something harmless, in which case it is not a problem. But as you pointed out, it can't be from your fertiliser dosing.
> 
> If you top up 180ppm water in your tank with 20ppm water, the ppm of the water should drop, not increase.


i see, where the hell the 20 ppm come from, cannot be from the soil, innert sand, i clean it every week before water change,


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## erwin123 (24 Dec 2021)

jaypeecee said:


> Hi Folks,
> 
> I just quickly scanned this thread - so, ignore me if this point has already been made - is the dissolved CO2 contributing to the electrical conductivity? If so, this would show up on a 'TDS' meter. Just a thought.
> 
> JPC



Just wondering, if you take the TDS reading at the same time every day, wouldn't the amount of dissolved CO2 be the same? i.e. the TDS increase has to be due to something else? This assumes that eminor is taking his TDS reading at the same time each day. (myself, I dose ferts daily around the same time before lights on), so thats when I check TDS.


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## John q (24 Dec 2021)

jaypeecee said:


> is the dissolved CO2 contributing to the electrical conductivity


As far as I'm aware the tds change from the inclusion of co2 is minimal, don't have anything to reference at hand but would be suprised if it adds 2~3 ppm difference from lights to lights off.


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## jaypeecee (24 Dec 2021)

John q said:


> As far as I'm aware the tds change from the inclusion of co2 is minimal, don't have anything to reference at hand but would be suprised if it adds 2~3 ppm difference from lights to lights off.


Hi @John q

You may well be correct. But this has piqued my interest and I feel that I should know more about it. I will therefore run an experiment - or two!

JPC


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## John q (24 Dec 2021)

jaypeecee said:


> Hi @John q
> 
> You may well be correct. But this has piqued my interest and I feel that I should know more about it. I will therefore run an experiment - or two!
> 
> JPC


Yes piqued my interest also, I've tested tds from co2 on to off and had very minimal change.

Your like me @jaypeecee  we need to see, before we believe. Suspect the issue is related to solids, dissolved solids, and or solutions .


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## jaypeecee (24 Dec 2021)

John q said:


> Yes piqued my interest also, I've tested tds from co2 on to off and had very minimal change.
> 
> Your like me @jaypeecee we need to see, before we believe.


Hi @John q 

I also did a simple experiment. As my CO2 cylinders are in use on tanks, I tried the Heath Robinson approach...

I popped my conductivity meter into 100ml of RO water. The reading was 5 microS/cm. Then, I exhaled a few times via some 4mm tubing into the water. After about five exhalations, the conductivity had risen to 11 microS/cm.  Clearly, the exhaled CO2 was forming carbonic acid, H2CO3 (as I expected) and this increased electrical conductivity. Nothing earth-shattering there.

I would be interested in knowing a few more details about your experiment, e.g. volume of water, CO2 injection rate, CO2 ON duration, etc.

All the best.

JPC


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## John q (24 Dec 2021)

jaypeecee said:


> I would be interested in knowing a few more details about your experiment, e.g. volume of water, CO2 injection rate, CO2 ON duration, etc.


No worries jpc.

Having read on the "Web" co2 increases tds I ran this test.

240l tank with a low inital tds. Checked reading before gas on, tds around 170, ph 7.3. Injection rate through the roof, only had 1 internal diffuser at this time.

4hrs later ph was at 6.4, lights came on, tds reading was 171.
I don't use a fancy tds meter, so results should be taken with a pinch of salt.

I'm sure the guru's on this site will explain why co2 plays no part in raising tds levels (the science behind it) I'm not a guru, I'm thick.

Merry Christmas jpc 😘


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## Maf 2500 (24 Dec 2021)

Nearly all of the CO2 injected into water remains as dissolved CO2 and therefore does not affect TDS. The amount that is converted to acid is so small that it would not really be detectable.

More info from people more knowledgeable than myself: Does injecting CO2 into the water change TDS?

Merry Christmas


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## MichaelJ (24 Dec 2021)

Hi @eminor   Please post a full tank shot, so we can see what's going on with respect to plant mass, hard scape, substate etc. also what media are you using in your filter.  Any bit of information may help to shed light on this. Are you adding anything else to the tank besides food and traces during the week?  and what food and what fish?

Merry Christmas to all,
Michael


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## John q (24 Dec 2021)

jaypeecee said:


> Then, I exhaled a few times via some 4mm tubing into the water. After about five exhalations, the conductivity had risen to 11 microS/cm. Clearly, the exhaled CO2 was forming carbonic acid, H2CO3 (as I expected) and this increased electrical conductivity. Nothing earth-shattering there.


Just an after thought.   We also exhale nitrogen and carbon monoxide, amongst other gases. Maybe this contributed to total tds in your test?


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## JoshP12 (24 Dec 2021)

Root tabs?


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## eminor (24 Dec 2021)

MichaelJ said:


> Hi @eminor   Please post a full tank shot, so we can see what's going on with respect to plant mass, hard scape, substate etc. also what media are you using in your filter.  Any bit of information may help to shed light on this. Are you adding anything else to the tank besides food and traces during the week?  and what food and what fish?
> 
> Merry Christmas to all,
> Michael



there is pictures of sand, filter,

i removed noodles since ceg told me that was the biggest influence on the flow, so in the filter so basically there's only those foam, there are big enough i think, could that be the issue ?

 i trimmed plants yesterday 






i spotted a co2 deficiency on a plant recently I think that's because i reduced the co2 level due to fish gasping, i fixed it i think





Other deficiency here on the crypt i think ?





too much co2 ? can still see green in it, hardly on pictures


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## jaypeecee (24 Dec 2021)

John q said:


> Having read on the "Web" co2 increases tds I ran this test.


Hi @John q

Confusion arises because the term 'TDS' is misleading in this context. A TDS meter does not measure total dissolved solids. Instead it measures electrical conductivity and then estimates Total Dissolved Solids based on assumptions made about the composition of the water. In order to actually measure Total Dissolved Solids, it is necessary to drive off water at elevated temperature and then weigh the residue. That's why bubbling CO2 through water _appears_ to increase TDS (because it increases electrical conductivity).

Hope that clarifies things.

JPC


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## jaypeecee (24 Dec 2021)

John q said:


> Just an after thought.   We also exhale nitrogen and carbon monoxide, amongst other gases. Maybe this contributed to total tds in your test?


Hi @John q 

Please see Post #39.

JPC


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## erwin123 (25 Dec 2021)

Anyway Eminor, its good that you are still looking into your CO2 as UKAPS says this is the cause of 90% of plant growth problems.

While measuring a 20ppm TDS increase every day with no obvious cause is an interesting mystery, it may not be the cause of your plant problems. Anyway, keep measuring to confirm whether its increasing by 20ppm everyday?  (measure at the same time each day to eliminate any "CO2 effects" (if any))


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## eminor (25 Dec 2021)

erwin123 said:


> Anyway Eminor, its good that you are still looking into your CO2 as UKAPS says this is the cause of 90% of plant growth problems.
> 
> While measuring a 20ppm TDS increase every day with no obvious cause is an interesting mystery, it may not be the cause of your plant problems. Anyway, keep measuring to confirm whether its increasing by 20ppm everyday?  (measure at the same time each day to eliminate any "CO2 effects" (if any))


Day 3 : 205 ppm, still don't know where the 5 ppm come from, could be plant poop ?

Yes Co2 is insanely hard to manage


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## jaypeecee (25 Dec 2021)

eminor said:


> Day 3 : 205 ppm, still don't know where the 5 ppm come from, could be plant poop ?


Hi @eminor 

5 ppm is such a low figure in this instance. I would suggest that it be disregarded - unless you think I'm overlooking something.

JPC


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## erwin123 (26 Dec 2021)

My TDS is surprisingly stable so far. It increases 5ppm after dosing which is within expectations (I dosed about 3.8ppm plus whatever waste is generated by plants/shrimp).  I started 600ml daily water topup with spare bottles of RO drinking water but mathematically, 600ml will have an insignificant impact on TDS

______________
After WC before dosing - *120-125 *(can't remember exactly)
after dosing: didn't record

day 2
after dosing: *130*

day 3 (changed 5 litres of water before measruement)
before dosing *125*
after dosing *130*

day 4
before dosing *131*
after dosing, end of photoperiod *136*

day 5
before dosing *135*


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## JoshP12 (26 Dec 2021)

Your substrate is inert ... I reckon you've added root tabs. 

If they are seachem, you will have massive TDS increase because they are not balanced due to**. 

If you added a non-tropica/miracle gro variety that has lots of **Ca/Mg in it, the same will happen. 

Regular root tabs in that substrate will also cause it to creep.


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## eminor (26 Dec 2021)

JoshP12 said:


> Your substrate is inert ... I reckon you've added root tabs.
> 
> If they are seachem, you will have massive TDS increase because they are not balanced due to**.
> 
> ...


I think that was the mistake i made, added 6 roots tab months ago, it's non-tropica thing, i forgot it...

There's aquabasis plus in the bottom, lots of it, could that be the roots tab that cause poor grow ?

I want to try tropica soil, sand seems bad, i don't know if it's really possible to grow difficult plant in sand.

How long until the root tabs decompose ?

sorry for my english


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## erwin123 (28 Dec 2021)

1 week TDS profile. Start *120-125ppm*, end *139ppm*
Daily top up 700ml of 0ppm water.

Eminor, have you kept up your daily monitoring of TDS? Whats your total weekly increase?
___________________
day 1 - *120-125 *(can't remember exactly)
day 2:  *130*
day 3 (5l WC, 70ppm):  *125, 130*
day 4 *131, 136*
day 5 *135*
day 6 *139 (*after adding 10x Starxcote root tabs - looks like no leakage into the water), *143*


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## eminor (31 Dec 2021)

Hi, i changed my soil, from sand to fluval stratum, some plants like pinnatifada or myriophyllum refused to grow well, it's been 3 days since i switched, it seems so good...

But there is a question, i know that active soil do not like hard water, and i use rain water, EI, problem is i don't have any calcium ferts powder, so i'm afraid that if i use 100% rain water there will be some calcium deficiency ? right

my tap have plenty of it but i want the soil to last long :/ can i dose ei without calcium using 100% rain water ? thx


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## erwin123 (31 Dec 2021)

eminor said:


> Hi, i changed my soil, from sand to fluval stratum, some plants like pinnatifada or myriophyllum refused to grow well, it's been 3 days since i switched, it seems so good...
> 
> But there is a question, i know that active soil do not like hard water, and i use rain water, EI, problem is i don't have any calcium ferts powder, so i'm afraid that if i use 100% rain water there will be some calcium deficiency ? right
> 
> my tap have plenty of it but i want the soil to last long :/ can i dose ei without calcium using 100% rain water ? thx








I don't think you have to be too worked up about extending the lifespan of your aquasoil. The soil in my tank is a relatively inert Gex aquasoil most of which is 10 years old - I just kept pouring fresh soil onto the top (and ended up with a 12cm deep substrate - maybe I have anaeorbic bacteria under all that soil )

As the photo shows, a lot of the soil has crumbled into dust. I don't have Aquabasis or power sand at the bottom, its just straightforward Gex soil with some lava chips. Of course, recently I've been adding root tabs/pellets.

Do not underestimate the importance of tank stability. If you are constantly changing water parameters (tweaking your rainwater/tapwater mix, tweaking your fertilisation, changing substrate, etc), your plants don't have a chance to adjust.

Sort out one issue at the time, like if you add 5ppm of Fert, why does your TDS go up by 50ppm... that was the purpose of this thread.


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## eminor (1 Jan 2022)

erwin123 said:


> I don't think you have to be too worked up about extending the lifespan of your aquasoil. The soil in my tank is a relatively inert Gex aquasoil most of which is 10 years old - I just kept pouring fresh soil onto the top (and ended up with a 12cm deep substrate - maybe I have anaeorbic bacteria under all that soil )
> 
> As the photo shows, a lot of the soil has crumbled into dust. I don't have Aquabasis or power sand at the bottom, its just straightforward Gex soil with some lava chips. Of course, recently I've been adding root tabs/pellets.
> 
> ...


yes i stay with 2/3 rain water + 1/3 tap water, ppm is stable now


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## erwin123 (1 Jan 2022)

eminor said:


> yes i stay with 2/3 rain water + 1/3 tap water, ppm is stable now


Thanks great. Look forward to seeing more pics of your Furcata and Tuberculatum.
I've been looking for them in my LFS but no stock at the moment.


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## eminor (14 Jan 2022)

Hello, just a question, is Nitrates en Nitrogen related, if there is no3 there is nitrogen ?


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## dw1305 (14 Jan 2022)

Hi all,


eminor said:


> is Nitrates en Nitrogen related, if there is no3 there is nitrogen ?


Yes, is the <"short answer">. 


dw1305 said:


> Because NO3 has three oxygen atoms you need to use a conversion factor to go from mg L-1 (ppm) N to ppm NO3 (and vice versa). The RMM of NO3 is 14 (RAM N) +(3*16 (RAM O)) = 62 and the %N 14/62 = 22.6%.
> 
> To convert nitrate-NO3 (mg L-1) to nitrogen (N) (mg L-1): N (mg L-1) = 0.2259 x nitrate-NO3 (mg L-1)
> and
> ...



Nitrogen (N) gas (N2) is pretty much inert, this because of the <"triple bond between the nitrogen atoms">.  Once you have a free nitrogen atom it is highly reactive, which is why we refer to biologically active compounds, like ammonia (NH3) and nitrate (NO3)  as <"fixed nitrogen">. You have three oxygen (O) etc. atoms because of the triple bond.

cheers Darrel


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## MichaelJ (14 Jan 2022)

eminor said:


> Hello, just a question, is Nitrates en Nitrogen related, if there is no3 there is nitrogen ?


Hi @eminor  Everything @dw1305  said +  with the 15 ppm of NO3 your getting with the KNO3 dosing your getting ~3.5 ppm of N (and ~10 ppm of K).

Cheers,
Michael


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