so I decided to get off my butt and take the photos this evening... the kids went to bed early!!!
I have had this system up and running for about 6 months or so with no issues.
I actually have this system running two independent tanks, a 125 and a 110. I am sure that most controllers can be expanded enough to add a system like this to it rather than going with a new controller.
I have a fish room in the basement, under the stairs. In this room I have two 55 gallon drums for water storage. The one on the left is fresh water and the one on the right is salt. The plumbing shown in the picture is for transferring water from one drum to the other or to fill gallon jugs or buckets.
From this area I have 3 x 1/4" tubing running to each tank. The white is for RODI top off. The blue is to drain the tank. The red is to supply new SW to the tanks. Each of these tubes runs through a McMaster Carr solenoid valve (
McMaster-Carr). It is p/n 7877K53. It costs about $25 each. I have had some in my tank systems for approximately 5 years with no problems.
The controller is set up to operate everything once a day for each tank. The controller is an Aquacotroller JR. I think it and the DC8 outlet system cost $200 in a powerbuy. I also have a dual inline TDS meter. Since my incoming TDS is fairly constant, I am monitoring the RO output and the DI output. If the DI output starts to raise I need to change the resin. If the RO output starts to raise, I need to change the membrane.
The first thing that happens is that the auto top off kicks on for approximately 30 minutes. My autotop off consists of the RODI system being run directly to a float valve in the sump. The only way it fills the sump is if the valve turns on and the float is low. This give some redundant protection. By running it for 30 minutes I would get a max of 2 gallons of top off. I only use 1 or less. If something were to go wrong I would notice it well before the sump overflowed. You definitely want the system to top off first, so that you are always at a fixed water level before anything else happens.
After that turns off, I open the valve for the drain. Ideally this drain would be from a bulkhead setting the low water level. However, the sump was already in use so I could not drill it for a bulkhead. Therefore it is running off a siphon. This water is directed to a floor drain in the fish room. The valve stays open for 6 minutes. Based on the head I have on the system this drains approximately 1 gallon of tank water.
Finally the controller turns on the supply pump to send new SW to the tank. This pump can be any number of pumps, you want high head and low flow. Since I sell industrial pumps, I had a "demo" pump that I am able to use. This pump is turned on for 8 minutes and brings the water level back up to its original point. I need to modify this system to have the supply pump run to a float valve rather than just run off a timer.
As mentioned earlier I wish I had a bulkhead for the drain and a float for the supply. These are really the only mods that I would reasonably like to make. The one that I think is just too expensive would be to automate the making of SW in the drum. This would need a powder dispensing valve valve to put salt in and that would be too much.
I do check the salinity in each tank about every two weeks. Once I got the timing right there has not been an issue. However, if there is and I need to make minor adjustments it will be easy. If the salinity drops I can simply overfill with the new SW and allow evaporation to slowly raise the salinity. By overfilling the top off would not activate as the float valve would stay low. If the salinity gets too high I simply need to drain extra and let the top off make up the difference.
If anyone has comments or questions, let me know.
It'll be fun.
