Target levels are tricky as there's smart people with different methods. I figure its best to use these numbers as starting points for experimentation, since every tank is different. Chuck Gadd recommends 5ppm
NO3, but guys you mentioned advise 10:1
NO3 :
PO4, and their success has me trying it.
[tangent] You may find my experience helpful or interesting: after adding sump
NO3 stopped registering on my test (AP), and within a week there was an algae problem (as opposed to nuisance). One reason I added sump was to have larger volume/stability, so I happily started dosing KNO3. At this time I was also moving away from Excel to
DIY CO2 (I mixed both while steadily increasing/measuring
CO2 output). Algae was minimized quickly and my plants looked great. I kind of had a magic moment with my tank at this point, which is Feb update in my gallery/site. Then I decided I wanted all high light plants in main tank, and made things difficult
So, now I've added much more efficent lighting and am experimenting with macro dosing with guidance from AA (I have new, hard to get rid of algae). High light/
CO2/wet dry sump is really cool
imo (example: vinnymac's system is sweet) and they make for interesting and efficent filters. Fun to build, too. Still, high light planted is the steepest learning curve I've experienced in aquaria.[/tangent]
Yes, nutrient uptake makes dosing for positive reading a PITA for me, as my system eats a little more than 3ppm of
NO3 a day with constant photoperiod (I add ~24ppm
NO3 from KNO3 a week, so this guesstimate does not take into account
NO3 from animals). Dosing to 15ppm saves time and doesnt throw system out of whack, in addition to target ratio. If I understand linked post correctly, Travis has experienced up to 7.5ppm
NO3 loss/day with regular photoperiod, and has measured enough to almost count on it... very impressive when you think about it.
HTH