Re:NO3 the next day

[Thomas Barr <tcbiii at earthlink_net>]

> From: "Daphne Freeman" <daphne.freeman at charter_net>
> Subject: add nitrates the next day, but why....
> 
> Sorry for asking something that Tom Barr has addressed more than once but I
> can't seem to find it in the archives...
> 
> Why is it recommended that you add nitrates the day after a water change?  I
> remember being told to add everything else the same day but the nitrates the
> following day.
> 
> Daphne in Atlanta

Mainly to drive them low as possible before adding NO3 back.
If the NO3 goes near zero for a day or less that's fine.
Just not longer.
The idea behind this is simple.
Adding all the PO4, K, CO2 etc from fresh tap water, dosing etc drives this
NO3 very low. It purges your tank of NO3.
Then the plants really go after the NH4 if there's any.
The next day you lift this limiting nutrient and the plants are not stunted
at all but your tank is nice a clean and the algae really seem to hate this
pattern.
The NH4 may be the reason, the water change itself etc. Not sure why but it
does seem to work. Gives a better starting point and estimation for what
your tank's NO3 will be as you dose 2-3x a week with KNO3.
Regards, 
Tom Barr