DIY Automated salt water mixing system

[sphelps]

Dosing pumps clog up from participate all the time, it really doesn't take much. Even if you get participate I don't think a standard centrifugal pump will have any issues. Another idea is to eliminate the pump in the saturated tank and add an overflow from the saturated tank to the saltwater tank. To add saturated solution to the SW tank you pump water from the RO to the saturated which in turn overflows into the SW tank. Use a small power head in the saturated tank to keep things moving. Similar to what posted before except the sump is another holding tank for additional mixing prior to being moved into the aquarium, personally I still don't see the need for the extra step but these types of systems have to make sense to the owner more than anyone else.

[Seth81]

Hmmm in my experience I haven't had a dosing pump clog, regardless I would probably use a cetrifugial pump if anything. I do really like your over flow idea, it's more simplistic and more cost effective as I could implement it with just one more valve off the RO header.. I'll update that drawing in a bit.


To address your comment about the SW mixing tank not being needed, I agree that on paper it is not needed,however practically I think it is. If I allowed SSW water to mix with RO water in the sump it would be very hard to control the ratio or have any confidence that the right mixture was achieved until it's a little too late. Also because I will most likely have to use equally rated pumps for both RO and SSW ratio control will have to be done on a time basis...I.e SSW pump on for 1 minute RO pump on for 7. During the 6 minute period the RO pump is on, the sump will have too high of a salt content and this water will be sent to the display tank and could potentially do harm.

I see many advantages in having a third mixing tank, only disadvantage I can think of is cost and space.

[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.

[Seth81]

I was thinking might be easier to impliment with a level transmitter in the SW tank. I found one for about $150