The undertow, which I'm going to guess is comprised of the Andes, may or may not provide much in the way of Ca and Mg. I think that those particular elements, as most often found in rock, are rather easily eroded away by water, so the undertow could also be comprised primarily of silica, or volcanic or granitic or other igneous origin rocks. Dolomitic lime is comprised of compressed coral skeletons that have not been transformed except by time and pressure/weight (non-volcanic).
I should call a geologist friend to learn more.
I personally think that mix could use a larger proportion of compost, especially in relation to the peat and castings.
Originally Posted by Manijahtor
thanks for the advice bro! but i really dont think its necesary to use dolomite, the worm casting neutralizes the peat, plus the ashes are very alcaline.
That's not the only purpose of the dolomitic lime. It provides a huge amount of Ca and Mg as well as good trace elements. It's also much better for buffering than wood ashes are (and they don't provide much in the way of Ca or Mg).