Or dose 10ppm 3x a week?

3ppm per day ought to do it.
Also, fish loading is a large player here.

Plants can take up that much, it can(does mean that they will in all cases) make them grow faster.

But is faster growth your goal?
Is non limiting growth a goal?

For some, yes. In order to rule other limitations, you need to provide non limiting levels to investigate things individually.

For others, they are not interested in that, they also tend not to be good at isolating cause and effect as well

Limiting growth for horticultural reasons, say you want slower growth, then limiting light is the 1st option since we have control of that. That makes everything much easier.
Then comes CO2.
Then Nitrogen(NH4 and/or NO3)
Or perhaps PO4.


Regards,
Tom Barr