Base rock and topoff

So, I was wondering about putting a piece of base (totally dead) rock in the ATO reservoir, letting it sit in the perfect pH water, and raising the calcium and alk levels in that water before it's added to the tank. This should at least offset the drop in calcium/alk levels from adding the topoff (adding a gallon of water with 0 ppm to 10g of 400 ppm lands you with 11g of 363 ppm), and possibly would maintain alk/cal levels completely depending on the ratio of utilization to evaporation.

Is this a good idea? Does this make sense to anyone else?

 

it will raise the ph of the incoming water slightly, but that's about it. in no way will it significantly add calcium and alk. It won't hurt anything, but I doubt you would notice an added benefit.

 

Remember evaporation is only H2O not minerals.