DIY Automated salt water mixing system

[sphelps]

Personally I think a conductivity controller is needed for automating water changes and it needs to be in your tank as at the end of the day that's where you need to maintain constant salinity. With this in place I don't see cause for concern regarding stability, decreasing the flow rates from saturated and RO water can aid in stability and conducting smaller water changes more often rather than larger ones less often is also key to success. While I agree there are advantages to the additional mixing tank it would require another conductivity controller to serve a real purpose of adding saltwater at the right salinity. To me the added cost of this alone out weighs any advantages you would gain.

The other problem I see with it is space as you also mentioned. To me the idea behind the saturated method is purely based on saving space, otherwise it makes zero sense. There are complications involved with this method, there is no doubt. For one elements are not going to be added in the same concentrations compared to mixing salt the standard way but this issue is kept minimal with smaller changes less often and with the primary replenishment left up to other methods like dosing or a Ca reactor. In addition the batches are kept small as in one pail at a time, and not adding more until the prior is used up. Dumping a dozen pails in at a time will amplify any effects relating to imbalance. If space is not a concern why not just pick up a 150 gallon drum and mix a pail of salt every few months, eliminating any complications relating to the saturated method.