High-value Currencies should have expensive Seeds. If you harvest the crystals too often you spend a lot of crystals on Seeds. As you can Harvest Crystals anytime there is no preasure to be online. The levels of the Crystals themselves should not affect the outcome too much. those levels are intended to create a feeling of Progress. dissolving Crystals in the Solution increases the rate at wich the crystals grow. It is needed that the growth rate is the logarythm (I used the ln in the Picture) of the solved crytals. (or else the grow could become too fast,) you can also buy new Strings to dangle more Seeds into your solution. thw whole Thing should be a slow-paced longterm investment thing wich only requires minimal involvement by the Players. (it should be good for Players who can not be online very much)