[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: APD, nutrient method
Jeff Kropp jjke at pacbell_net wrote:
> You mention desired calcium concentrations of 30ppm in your post. As I
> recall Dave Huebert was saying 20ppm was more than enough and 2ppm was
> about what was needed for aquatic plants. Can I assume your experience
> has proved 30ppm necessary?
Quite the contrary. The concentrations are not critical at all; they are
only designed to be sufficient to ensure adequate nutrients. 30 ppm is a
rough approximation of the concentration you get using 1 tsp of calcium
carbonate per ten gallons of water and that's the only significance to
the value. I found that under initial conditions with peat, this was
being absorbed by the peat so I double the amount. The range of
tolerable calcium concentrations is one of the widest!
> By the way thanks for your post, I may try it when I reset-up to
> rectify the 140ppm of calcium leaching from beach gravel.
That's not too much calcium; many plants will thrive in hard water like
that. The problem with using a continuous source of calcium in a tank
with large sources of humic acid is that you're probably not going to
know your actual concentrations very well. That doesn't mean it won't