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Salt Water Chlorinator Monitor
I installed a Calimar Salt Water Chlorine Generator (CMARSHA60-3Y) earlier this year and I am very happy with it. My pool has never looked so good with (relatively) little effort compared to what I was used to and without having to handle chlorine.
Nothing being perfect, I do have a couple of gripes with it, but they are not show stoppers and can be addressed relatively easily.
The main issue is that there is no external indication if the generator is working or not. One needs to open the cover of the control unit and look at the LEDs. There are 4 fault conditions that can cause the generator to shut down: low salt, high salt, no flow or cell needs cleaning. So you need to regularly go to the controller and open the cover to make sure there are no faults.
Secondly, this being Florida, we tend to have lots of thunderstorms and on occasion, the SWCG trips due to nearby lightning and does not always restart automatically (I have to recycle power), which goes back to the absence of visual indication.
From what I have seen, the Calimar system I have is virtually identical to many similar units by Hayward and others and it is likely that they all come from the same place, so these issues are probably not unique.
To address these issues, I have built a small monitor system (based on an Arduino board) which drives an external flashing light in case of fault and also uploads cell current to the website Thingspeak.com (look for "Pool and Chlorine Generator Monitor"). This gives me an almost real-time indication if the SWCG is working and a graph of the last day or so.
I have documented the system in more details below.
For reference, in my installation, the SWCG runs at around 40% (you can adjust this with the potentiometer, a cycle is 3-4 hours long, and the chlorinator runs for a bit over an hour) and the chlorine level is 3-4 ppm. In the four months (as of end of August 2024) since I have had the system, the water temperature has been between 87 and 94F and there is absolutely no trace of algae or cloudiness of any kind. The Black&Decker variable speed pump (2HP) runs between 2,000 and 2,500 rpm 24/7. I sometimes run it at 3,000 rpm after a storm, if I think about it. I have not put it on a timer yet.
Here is what the ThingSpeak page looks like. In that picture, the setting was almost tto the max (~95%.) You can see the Low Salt warning came a few times, probably due to rain, but not enough for the generator to shut down.
The modification consists of adding a small board to the back of the display board. The Display board is attached to the main board with 4 plastic clips and connections are made with a connector, there is no desoldering required to remove the Display board. The new board supports an Arduino D1 mini Pro clone board and a few additional components to 1) acquire the cell current using a current transformer, 2) acquire the 4 fault outputs (low salt, high salt, low flow and clean cell) and 3) drive the flashing light (flasher) through a relay. The Flasher runs from the 24VAC from the transformer and the D1 mini Pro runs from the 5V available on the display board. The current consumption is about 50mA average and does not seem to be a problem for the chlorinator.
The modifications to the system are simple and mostly reversible (no need to cut any wire in your system.) You will need to drill two holes at the bottom of the enclosure and you will need to solder several wires to the existing Display board:
- Install the current transformer on one of the transformer output wires (it simply clips on the wire)
- Install taps on the transformer outputs (24V AV) to power the flashing light (these punch through the insulation but it causes minimum damage to the wire and the taps can be removed if desired)
- Drill two holes at the bottom of the enclosure for the WiFi antenna and the cable going to the alarm.
- Install the board to the back of the display board (double sided tape) and solder 6 wires to it.
- Install the wires to the flasher and the WiFi antenna (optional if you want ThingSpeak data logging).
The D1 mini Pro does come with both a U.fl antenna connector and a small surface mounted ceramic antenna. By default, the ceramic antenna is connected, even if your kit comes with the external antenna (see this for instance). To use the U.fl connector, you need to unsolder, turn 90 degrees and resolder a very small jumper that looks like a surface mount resistor (see picture below). You need a very steady hand and proper tools to do that without damaging the board. If you do not want the data logging through ThingSpeak, you do not need the WiFi antenna.
If you want to use data logging through the ThingSpeak website, you will need the external WiFi antenna since the controller is in a metal enclosure.
The flasher (from AliExpress) blinks when any of the 4 fault conditions are present, so I do not need to walk to the enclosure and open it to know if it's working normally or not, which is a great convenience, and it makes the WiFi/ThingSpeak datalogging capability completely optional. I have installed the flasher so that it is visible from the house.
The schematic is below, I will upload the software later.
I intend to make a clean printed circuit board and if someone is interested, I coud make a short run of boards and a kit of everything you need with instructions to install it. From what I have seen, it would probably work on a Hayward or any other clones of this system.
1. Outside view, with the Controller/Power Supply and the alarm flasher at the bottom. I made a sun shade to reduce sun load. The Controller is mounted to the north facing fence.
2. Front panel of the Controller when the cover is open.
3. Bottom view showing the WiFi antenna and the cable going to the flasher (far left corner). The cable near the WiFi antenna goes to the flow switch.
4. Internal view of the Controller with the front panel removed. You can see the current transformer (in blue)
5. Backside view of the Display board with the perf board supporting the D1 mini Pro board.
