Substrate ferting - KNO3

[f1ea]

Hello all,

I am currently setting up a large low light tank, using mineralized soil as a substrate. Is it safe to use micronized KNO3 in small quantities under the substrate??

Or would i better off leaving the soil as it is, and dose the KNO3 to the water column later if needed. I am not sure if the KNO3 mixed within the substrate can decompose and release ammonia.

Thanks in advance!

[bradac56]

I'd leave it as is and dose the KNO3.

- Brad

[plantbrain]

Originally Posted by f1ea

Hello all,

I am currently setting up a large low light tank, using mineralized soil as a substrate. Is it safe to use micronized KNO3 in small quantities under the substrate??

Or would i better off leaving the soil as it is, and dose the KNO3 to the water column later if needed. I am not sure if the KNO3 mixed within the substrate can decompose and release ammonia.

Thanks in advance!

KNO3 will not turn into NH4.
NH4 can and will turned into NO3 with O2 present.

NO3 is exported via plant uptake or water changes, filter cleaning etc, perhaps is some rare cases, NO3-> N2 gas.

NO3 is extremely mobile in water, so it's not going to stay out anywhere you try and add it.

So add it to the water column little by little

Regards,
Tom Barr

[f1ea]

Originally Posted by plantbrain

KNO3 will not turn into NH4.
NH4 can and will turned into NO3 with O2 present.

NO3 is exported via plant uptake or water changes, filter cleaning etc, perhaps is some rare cases, NO3-> N2 gas.

NO3 is extremely mobile in water, so it's not going to stay out anywhere you try and add it.

So add it to the water column little by little

Regards,
Tom Barr

Exactly, but my doubts were related to adding the KNO3 under the soil, which under probable anaerobic conditions could turn into ammonia.

But after reading your suggestions i think it will be a lot safer to dose it to the water column, allowing me to dose as required.

Thanks fellas!

[plantbrain]

Originally Posted by f1ea

Exactly, but my doubts were related to adding the KNO3 under the soil, which under probable anaerobic conditions could turn into ammonia.

No!
This will never occur in a planted tank.
It can occur in some wetland sediments that have extremely high organic matter loading and are extremely anaerobic.

No one in aquariums has such conditions.
This is way beyond Sulfur reduction, and it's a very slow process.........
Who ever told you this is full of beans and has no idea under what conditions are required for this to occur.

This takes over 8 electrons of energy per NO3 converted, this is not a fast process or one that easily achieved. It's actually the hardest of all the transformations.

The bacteria required must be under pure anaerobic conditions with no O2 even remotely close, if you have plant roots, this is never going to occur as they give off lots of O2, as well as the pore/grain sizing in most sediments is too large to for this as well.

The redox levels must be below 0mV, which is extremely low.
In order to do that, you need huge amounts of organic carbon coming in, this is not possible without also depleteing the O2 in the water column and the NH4 leaching as well.

Not good conditions for any fish.

But after reading your suggestions i think it will be a lot safer to dose it to the water column, allowing me to dose as required.

Thanks fellas!

Much safer............let the plants reduce the NO3 to NH4, not bacteria........plants do the same thing, but without the requirement of very low redox, no O2 and NH4..........

If you want non toxic forms of N, add fish and KNO3.......

Regards,
Tom Barr

[f1ea]

Great info Tom!

i was VERY surprised when i was told NO3's could simply transform back into ammonia. Oxidation is a far easier process than the opposite, so it left me quite puzzled. That's why i posted the question... Thanks a lot!

Regards.

[plantbrain]

Originally Posted by f1ea

Great info Tom!

i was VERY surprised when i was told NO3's could simply transform back into ammonia. Oxidation is a far easier process than the opposite, so it left me quite puzzled. That's why i posted the question... Thanks a lot!

Regards.

Well, folks read one thing, then do not realize under what conditions are required for that bacteria transformation to occur. So they say it, think they can add KNO3 that will convert etc.

They just do not understand what they are talking about, it's like taking only 1 sentence from Obama's speech and carefully editting it to make him look bad or good. You do not understand the entire speech at all, just what the person editing it wanted you to hear and impress upon you.

Same type of thing here.

Use plants to do that.

If you are looking for a long term source for sediment ferts............try osmocoat and MS, ADA AS etc..........all these are much more useful, or dose KNO3 to the water column little by little when you feed fish or 2-3 x a week, or maybe 1-4X a month if you do non CO2 methods etc.

Regards,
Tom Barr