How much is too much NO3?

[detlef]

Tom,

the report on nitrogen cycling stated a 50% mortality rate for C.japonica after a 3 day exposure to 120ppm nitrate (nitrate solely derived from KNO3). Somewhere else you were saying that more than 20ppm NO3 won't be necessary at all for any plant if I remember correctly. On the other hand you reported excellent plant growth with dosing 11ppm KNO3 every other day and 70% water change (no fish or herbivores in this tank).

What if you have a (non EI) tank hoover around 30,40,50ppm NO3 permanently with 20% water change each week? Do you think that this might obstruct plant growth? And what about fish health?

Regards,
Detlef

 

[Tom Barr]

Re: How much is too much NO3?

I think 40-60ppm over long time frames might have some impact, but I've not seen it over a 12 month time frame.

But 30-40ppm max is plenty.

So keeping it lower is not that much of an issue.

Some argue for redcued water change volumes, not sure why, take the same time pretty much to do 20% as 50% once the Python is hooked up etc and small tanks matter even less.

RO make up water etc is an issue but most blend so that is less of an issue unless you need more than say 30 gal of RO.

Regards,
Tom Barr