Fertilization frequency

[Blinky]

I've been testing my water pretty much daily, trying to get a feel for how often to fertilize my plants.
The trace elements fertilizer and the NPK fertilizer I have both say on the bottle to dose (1 cap/20g) 1-2 times per week, but I'm finding that I have to dose more often and I'm a bit concerned and wanted to ask if that's okay.
Here's an example: I tested NO3 and PO4 yesterday after I fertilized - NO3 ~10ppm, PO4 ~0.5ppm. Tonight I tested again and NO3 was down to ~5ppm, PO4 was at 0.25ppm. I added another dose of fertilizer to get the levels back where they were yesterday.
I added traces the day before yesterday, I'm wondering whether I should be dosing them more often than suggested as well. I can't test all the chemicals and I was wondering if dosing traces too often leads to some chemicals building up too fast and it's better to just do as the bottle says even if iron levels get low (Fe goes from 0.5 down to 0.25 in 72 hours).
Thanks for the help
[Edit] To give you an idea of how fast these guys are growing, the spadeleaf that was at least 1" from the surface ~36 hours ago in this picture
http://www.aquariacentral.com/forums/showthread.php?t=36972
is breaking the surface today. A few days ago I thought the tank looked fantastic, today I looked at it and realized I'm going to have to do some pruning pretty soon or the fish won't have room to move! I don't mind this, it will give me a constant project to work on, but I do want to make sure that I keep them healthy. [/edit]

 

[plantbrain]

Most recommendations are conservative of labels.
You can easily add 2-4x these if the plants are in a higher light/CO2 rich tank.

You can double or triple the levekls you have stated without algae.

The best bet is to simply watch your plants and maximize the growth rates.
If high growth rates disagree with you, try less lighting.

That makes the most sense.

Your rates are not that far off, depends on the test kits you are using.
So now you know.


Regards,
Tom Barr

 

[djlen]

Regarding the traces. Figure out how many mls. you are dosing per week and break it up into daily dosages. This will keep your Fe in the water table and available to the plants most of the time.
The N and P should be kept at P=1.0 - 1.5 and the N=10 - 15. Keep dosing and you will come to a point where you'll have a feel for what your plants are using and be able to dose the amount to sustain the required levels for a few days at a time.
A weekly water change (50 - 60%) will keep you from building excess nutrients.
The important thing that I've learned over the years, is that over working the tank will cause problems because it plays with the balance. Work on only 1/3 or less of the tank at a time. Make your changes small and frequent, rather than large after the tank has gotten out of hand.

Len

 

[Blinky]

Thank you thank you thank you!