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Low nitrate level

Joined
27 Jul 2022
Messages
31
Location
Wales
Hey guys, I’m pretty new to this AIO ferts method. I’m currently dosing 75ml per week of TNC Complete to my 750L system. Weekly water change of ~50%.
Short and simple is my NO3 is down to 5ppm 2 days after water change and dosing. I’ll admit I forgot to test NO3 after dosing but I did test before the water change and NO3 was barely detectable.
Now is it as simple as just upping the dosage of the AIO fert or do I need to supplement NO3 additionally? Currently I’m only able to test NO3.
I was under the impresssion TNC Complete follows the EI method of ferts, which doesn’t really matter if you overdose - or have I got that totally wrong?
I will be moving over to making my own ferts from dry salts eventually but grabbed the AIO just to get the ball rolling.
Thanks folks
 

_Maq_

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NO3 colorimetric tests are unreliable. Better than that, you observe your plants for deficiency symptoms. (I'm pretty sure there is a person called Darrell somewhere around who'll happily develop this suggestion.)
Generally, you'll do better with (a) dry salts, (b) report from your source water provider. Put together, you'll know your water better than using NO3 tests.
 

xZaiox

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Maidstone, UK
What test kit are you using to test for nitrates? They can be a bit finnicky. For instance, the API nitrate test kit requires you to vigorously shake the #2 bottle and the test tube afterwards for like a good minute each (give the bottle a whack on a tabletop if using this test kit). I believe it contains a substance that falls out of suspension and has to be knocked back in to give a result. Although I will also add, that hobby grade nitrate test kits are generally regarded as unreliable, but I have no chemistry background and can't comment on that part.
 

_Maq_

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What test kit are you using to test for nitrates?
I have a spectrophotometer, pretty handy machine. But even its quite advanced colorimetric test for nitrates is prone to get distorted by many compounds which are quite common in aquarium water. So I don't use it and purchased a ion selective electrode.
 

John q

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@RoasterToaster
Short answer is you are adding about 6.6ppm of N03 (1.5N) to your tank every week, and depending where abouts in Wales you live your tap water might not contain a great amount of nitrate.
If you're not happy with something in the tank, maybe have deficiencies etc then add a bit more, it won't do any harm, especially as you're adding small amounts already 😉

Ps: your test kit is giving reasonable readings considering what you dose the tank, having said that running your tank dependant on test kit results is a slippery slope and often doesn't grow pretty plants.
 

RoasterToaster

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Wales
@RoasterToaster
Short answer is you are adding about 6.6ppm of N03 (1.5N) to your tank every week, and depending where abouts in Wales you live your tap water might not contain a great amount of nitrate.
If you're not happy with something in the tank, maybe have deficiencies etc then add a bit more, it won't do any harm, especially as you're adding small amounts already 😉

Ps: your test kit is giving reasonable readings considering what you dose the tank, having said that running your tank dependant on test kit results is a slippery slope and often doesn't grow pretty plants.
Thanks John, I’m in South Wales so our water comes from the Brecon Beacons. TDS is pretty low (around 55-60) so I would assume tap water has very low to negligible NO3.
Tank has only been running since early august. Currently all the plants seem nice and green and appear healthy.
Coming from a reefing background I’m aware that low nutrient systems can lead to dinoflagellate outbreaks, is this a risk in a planted FW system?
I will most likely dose a little higher for the time being and monitor.
If you don’t monitor your tank with testing, how do you know what might need adjusting chemistry-wise? Do you just use your plants as indicators or do you test periodically with lab based ICP? Thanks
 

dw1305

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Hi all,
If you don’t monitor your tank with testing, how do you know what might need adjusting chemistry-wise? Do you just use your plants as indicators or do you test periodically with lab based ICP?
I just use <"complete fertiliser"> (at the moment <"Solufeed 2 : 1 : 4">), <"plant health"> and a <"conductivity datum range">.

Have a look at <"Measurement of Nitrate with a Spectrophotometer">, that is pretty much <"where I've been for the last ten years"> and I'm happy with it as an approach, and I can't imagine that <"I'll ever use any other method">.

If you like it is the <"coffee not the froth">.

As a bit of background I have access to <"analytical kit">, but <"I very rarely use it now">. For nitrate (NO3-) the ion selective electrode @_Maq_ references is <"your best bet">, but they are expensive bits of kit.

cheers Darrel
 
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RoasterToaster

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Hi all,

I just use <"complete fertiliser"> (at the moment <"Solufeed 2 : 1 : 4">), <"plant health"> and a <"conductivity datum range">.

Have a look at <"Measurement of Nitrate with a Spectrophotometer">, that is pretty much <"where I've been for the last ten years"> and I'm happy with it as an approach, and I can't imagine that <"I'll ever use any other method">.

If you like it is the <"coffee not the froth">.

As a bit of background I have access to <"analytical kit">, but <"I very rarely use it now">. For nitrate (NO3-) the ion selective electrode @_Maq_ references is <"your best bet">, but they are expensive bits of kit.

cheers Darrel
Thanks Darrel, I’ll take a look and see how i fare
😁
 

RoasterToaster

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Some great points of reading there, thank you. My previous experience in keeping marine has had me a bit “over focussed” on numbers 🤦‍♂️
I guess if plants are healthy and green, then things are good.
I’ll definitely be looking into Solufeed 2:1:4 as it looks to be much cheaper than premade AIO
 

John q

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Thanks John, I’m in South Wales so our water comes from the Brecon Beacons. TDS is pretty low (around 55-60
Well I consider myself lucky to have tap water at 65~70 tds, if I were you I'd consider yourself blessed. For what its worth you can check your water report online, just search water quality and then enter a postcode. This should give you a rough idea of what's in there but I suspect there won't be much of anything in it.
Coming from a reefing background I’m aware that low nutrient systems can lead to dinoflagellate outbreaks, is this a risk in a planted FW system?
Erm, probably a bit out of my depth on this but not that I'm aware of, infact the only thing that I can relate to regards dinoflagellates would be Oodinium (velvet) and to the best of my knowledge this isn't related to nutrients.

Of course some people suggest low N03 levels have some relationship with cyanobacteria, and I've personally eradicated green spot algae by dosing high amounts of P04. Is this something you need to worry about? I'd cross that bridge IF and when you come to it.
If you don’t monitor your tank with testing, how do you know what might need adjusting chemistry-wise?
I used to do a lot of testing and appreciate that some people enjoy it, for me it became rather laborious and I could pretty much predict the results before I did them.
You see it's fairly easy to work out what you put into the tank so can make an educated guess what's in there, and if you're doing 50% weekly water changes that should take care of any nasties accumulating from the fish or other unknowns, that of course assumes the plants haven't already done this for you. I also regularly test conductivity which doesn't tell you what's in the water, but gives you a good idea if something is starting to creep.

Regards low nutrients, well as darrel suggests the plants will tell you if things are lacking. The best thing I did was use a floating plant (amazon frogbit) because they really are the first to let you know if things are lacking.

Hope some of the above helps.
 

RoasterToaster

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What test kit are you using to test for nitrates? They can be a bit finnicky. For instance, the API nitrate test kit requires you to vigorously shake the #2 bottle and the test tube afterwards for like a good minute each (give the bottle a whack on a tabletop if using this test kit). I believe it contains a substance that falls out of suspension and has to be knocked back in to give a result. Although I will also add, that hobby grade nitrate test kits are generally regarded as unreliable, but I have no chemistry background and can't comment on that part.
It’s NTLabs test kit. I have no idea whether it’s any good or not. I’m used to testing from my marine days but there were a wider range of test kits available and we could also send off for icp analysis to compare test result accuracy - most of the kits I used for my reef tank gave fairly consistent results with icp analysis (even if just indicative).
 

RoasterToaster

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NO3 colorimetric tests are unreliable. Better than that, you observe your plants for deficiency symptoms. (I'm pretty sure there is a person called Darrell somewhere around who'll happily develop this suggestion.)
Generally, you'll do better with (a) dry salts, (b) report from your source water provider. Put together, you'll know your water better than using NO3 tests.
That’s the consensus I’m seeing. Thanks for the input. I am now looking into dry salts as opposed to premade AIO. Cheers
 

dw1305

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Hi all,
My previous experience in keeping marine has had me a bit “over focussed” on numbers 🤦‍♂️
I guess if plants are healthy and green, then things are good.
Sea water is a pretty standard all around the globe, this means you have a known datum to aim for and also that marine organisms have evolved in very stable environment.

Fresh water is much more variable, and a lot less salty, all of which add uncertainty to testing.

Cheers Darrel
 

RoasterToaster

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Well I consider myself lucky to have tap water at 65~70 tds, if I were you I'd consider yourself blessed. For what its worth you can check your water report online, just search water quality and then enter a postcode. This should give you a rough idea of what's in there but I suspect there won't be much of anything in it.

Erm, probably a bit out of my depth on this but not that I'm aware of, infact the only thing that I can relate to regards dinoflagellates would be Oodinium (velvet) and to the best of my knowledge this isn't related to nutrients.

Of course some people suggest low N03 levels have some relationship with cyanobacteria, and I've personally eradicated green spot algae by dosing high amounts of P04. Is this something you need to worry about? I'd cross that bridge IF and when you come to it.

I used to do a lot of testing and appreciate that some people enjoy it, for me it became rather laborious and I could pretty much predict the results before I did them.
You see it's fairly easy to work out what you put into the tank so can make an educated guess what's in there, and if you're doing 50% weekly water changes that should take care of any nasties accumulating from the fish or other unknowns, that of course assumes the plants haven't already done this for you. I also regularly test conductivity which doesn't tell you what's in the water, but gives you a good idea if something is starting to creep.

Regards low nutrients, well as darrel suggests the plants will tell you if things are lacking. The best thing I did was use a floating plant (amazon frogbit) because they really are the first to let you know if things are lacking.

Hope some of the above helps.
Thanks, lots of good advice coming through. I’m like you and not a fan of testing. But as the tank is still young I was just wanting to try and get a baseline. I think I’m just going to stop overthinking it and let the plants tell me if anything is missing. Tank is still low tech at the moment so nutrient uptake isn’t going to be massive. Good to know that dinos aren’t an issue like with reef tanks!!!!!
 

dw1305

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Hi all,
But as the tank is still young I was just wanting to try and get a baseline.
That was partially why I started using a datum <"conductivity range">. Conductivity isn't the most useful measurement, but it has certain advantages, because the meters are,
I think I’m just going to stop overthinking it and let the plants tell me if anything is missing
Both <"Estimative"> and <"Duckweed"> indices, even though they are very different in concept, and were developed entirely independently, were designed to do away with the need for accurate water testing. This was just a reflection <"of the difficulties involved"> with accurate water testing.

Both Tom Barr (@plantbrain ) and myself <"worked in situations"> where we had access to analytical equipment, and could get accurate values for many water parameters, but we recognised that methods <"that didn't rely on water testing"> were more likely to <"provide successful solutions"> in the long run.

It would be fair to say that Tom myself, even though we are both loosely Plant Scientists, have <"very different approaches"> to our jobs.

cheers Darrel
 
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_Maq_

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I too possess some relatively advanced measuring tools, but I've got to the same conclusion: measuring is laborious and in the end always a bit expensive.
That's why I turned to RODI water and mineralize completely. Thanks to that I know fairly well what my water contains. And then I observe plants' reactions. If a trouble occurs, I re-arrange my mineralization scheme. It seems a bit laborious, too, but I think it is not. Instead of guessing blindly what may be the source of trouble and adding whatever comes to mind (or colleagues suggest), I know pH and the amount of all ions in the water, and that makes fixing any deficiencies far easier. What remains is observing different responses among species. That's the funny part of it.
 
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_Maq_

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It would be fair to say that Tom myself, even though we are both loosely Plant Scientists, have <"very different approaches"> to our jobs.
I think Tom Barr's practice of changing large share of water in weekly rhythm solves not only 'his' dosing problem but also 'my' problem - accumulation of organics. What does your WC routine look like?
 

dw1305

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Hi all,
I think Tom Barr's practice of changing large share of water in weekly rhythm solves not only 'his' dosing problem but also 'my' problem - accumulation of organics. What does your WC routine look like?
I change about 10%- 15% water every day <"Frequent small water changes or weekly large?">. I use 3.5 L (<"6 pint">) <"disposable Milk cartons"> to store my rain-water in. I've done this <"for the last ~20 years">, mainly because it <"suits my morning routine">.

When I had more fish I used to change a bit more water, but still use the conductivity datum / Duckweed Index as a guide to whether I was changing enough water. If I've been away from home for a while I'll do a bigger volume water change and I've never found this bothers the fish (butt and tank water will be <"not dissimilar in chemical composition">).

In the summer the tanks always get a bit more in the way of water change. There isn't a fish-keeping reason for this, it is just I <"water the containerised plants more"> and I cycle the water from the water butt, into the tank, out of the tank and out to the plants. This is partially because I'm too lazy to net the Daphnia and this ensure they end up in the fish tanks, rather than watered on the plants.

cheers Darrel
 

RoasterToaster

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Changing water (even a small %) on a daily basis wouldn’t be feasible for me with a 750L system so I do a ~50% change on a weekly basis. Purely to keep DOC’s down and prevent excess buildup of nutrients - it seems plants are a lot more tolerant than corals are.
I will most likely look into a conductivity probe in the not too distant future just to keep an eye on if anything is drifting.
I did contemplate using remineralised RO bit with my source water coming in at 50-60 tds (and after some advice on this forum) I decided it wasn’t worth the extra hassle and cost when I’m changing around 350L or so each week.
I really appreciate all the insights I’ve had to your varying approaches. What I’ve decided is that I’ll carry on as I have done so far, if it ain’t broke, don’t fix it!!!
It’s just a different frame of mind from reef keeping that I need to adjust to!!!!
Thanks guys
 

RoasterToaster

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Thanks for all the input guys. I’m probably going to go down the route of solufeed 2:1:4 for my next step into ferts, being an AIO and at a much better price point than TNC.
Now the question is, how much should I be dosing?
If I’m aiming for 10ppm NO3 then applying Darrells calcs from another thread, I should need 11.25g (for my 750L system).
Does that sound right? Dosed on a weekly basis with 50% weekly water change?
(The previous example used 2.7g in 180L system)
Thanks guys
 
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