Water Mixing Station:
One of my goals for this build is to decrease barriers for performing maintenance and repeat tasks. One impactful way to do this was to design and build a salt water mixing station that can service tanks and ATO reservoirs throughout my home.
This is a long post, but when starting out I always found myself wishing for a little more detail in peoples' build threads.
Requirements:
Stand -
Fit inside 1/2 Hallway closet
Saltwater proof material
Hold 1.5x weight capacity (~250lbs min)
Water Containers -
Dedicated RO and Salt bins
Food Grade
Hold 15-25% display tank volume each (17 gals min)
Store extra salt, water change gear, and salinity testers
Functionality -
High pressure internal pumps
Workable height
Handle and detect Spills
Easy transfer Between bins
Outbound hose reaching all tanks
Sediment filter and heating in salt bin
Individually switched electrical and GFCI
Easily disassembled for modification and cleaning
Auto shutoff
Optional Extras:
Auto flush
Optimal PSI
Optical eye auto shutoff (
TODO)
Wireless Pump Control
Water Containers:
I went with two 80lb Gamma Vittles Vaults, which are food grade and hold ~20 gallons each. They have wide mouths for easy pump installation and bin cleaning. I see them used by home-brewers often and the manufacture says they are fine for liquid storage.
Stand:
For the stand I selected 18" x 48" NSF black epoxy wire shelving. It can hold more than twice the required weight and is resistant to corrosion. I searched out a tray that fits into the shelving and will hold the volume of one full water container. The tray prevents water from getting into the storage shelf below and gives me some safety if either bin leaks. A plastic liner was placed on the bottom storage shelf to make sliding salt buckets in and out easier. After taking some basic measurements, I sketched a rough design and ordered parts from a restaurant supply store and a hydroponics vendor.
Container Plumbing:
This took me a few iterations. Eventually I settled on a design using internal pumps that can be easily disassembled, modified, and cleaned. For comfortable standing access to valves I went with top mounted bulk-heads and plumbing.
After a trip to the hardware store for 3/4" PVC and ordering some plumbing fittings and python water-change tubing online I was able to get to work.
The initial build went relatively smoothly and I re-learned a good deal about working with plumbing. I went with schedule 80 ball valves and took the time to clean, bevel, and prime each piece. Where applicable, threads were sealed with Great White pipe joint compound.
Pumps and Sediment Filtration:
After measuring the distance to my tanks, and calculating some head pressures, I settled on a pair of Mag Drive 18 pumps. I attached these to 3/4" braided tubing with barb fittings and unions for easy cleaning and in case I ever need to run the system off of just one pump.
Next I put together a drop-down re-circulation tube for the salt mixing bin. To prevent crud buildup over time, I fixed a 4" filter sock to the bottom of the drop-down tube via a zip tie that slips behind a 90° elbow. This elbow is slip fit so I can change out the sock. I placed a union on the drop-down tube for easy removal and sock change out.
Measurements and RO/DI Hook-Up:
The next step was to install a float valve into the RO/DI container to save my floors and trigger the RO/DI unit's auto shutoff system. After that I added gallon marking to the bins. I did this second task by suspending a light inside the bin, incrementally adding water with a measuring bucket, and marking the lines with a level and permanent marker. Not the cleanest labeling, but given the low cost of the bins it was worth the aesthetic trade-off. I then placed a ball valve in-line with the RO output line the so I can easily disconnect the container from the RO system without having to remove the float valve.
Electrical and Wire Management:
I ran a heavy-duty extension cord through the wall into the closet, hooked up an in-line GFCI, mounted an individually switched power bar, and secured everything with drip paths in mind using Velcro ties. During this step I also mounted a heater inside the salt mixing bin using a heater holder from Matt at Octo Aquatics.
Pressure and Auto-Flush:
As noted in my previous post, my water pressure to the RO/DI unit was only 40 PSI. To combat this, I installed an Aqatec booster pump, and while at it, added an auto flush valve and shut-off solenoid. I adjusted the pressure up to 80PSI and saw a drastic boost in my production speed; currently making 20 gallons in about 2hrs and 15mins.
Mixing Station Complete:
Here is the final product! So far I have made about 250 gallons of saltwater and I am very happy with how things turned out. It is easy to mix and later heat salt water, and fast to transfer either salt or RO water to tanks and reservoirs on either floor of my home.
Enhancements:
Here are a few small things I have done since the initial build. I added a small power-head to the bottom of the salt bin facing upward to speed up initial mixing; this allows me to dump salt in faster. For added safety, I placed a Watchdog leak sensor under the stand. I labeled everything in case a tanker sitter or my significant other needs to do anything while I am away. Lastly, I hooked the two pumps up to WIFI outlets so I can switch them on and off tank-side without walking back to the station.
Next Steps:
Live rock \ Sand
Build approach
