[Seth81]

Originally Posted by Zoaelite

Hmmm, I was more leaning towards the point that the calcium bicarbonate would precipitate onto the impeller itself causing dysfunction.

I must be wrong if Steve had no problems with abiotic precipitation via supersaturation though.

Well I doubt it would be a problem for most pumps, but to be sure a positive displacement pump (such as a dosing pump) could be used to guarantee that precipitate wouldn't be an issue. Which would also help to ensure a good slow mixing of the solutions too. BRS sells a 50 ml/min dosing pump, based on a 7:1 ratio of RO to SSW water the dosing pump would need to be on for 3.5 hours to make up 20 gallons, which isn't too bad I think.