Chlorine Automation

May 23, 2016
5
Los Altos, CA
#1
I'm interested to find out if other people in this community have information about chlorine sensors or if they are interested in what I have done with my Jacuzzi J-375 hot tub to automate it.

I bought the Hot Tub in 2015 or 2016. The water used to last about 3-6 months, the pool service did not keep the levels right and I was running the pumps about 16-20 hours a day. Then I found out about TFT and started to maintain my own chemicals.

About a year ago, I decided to automate the Hot Tub control. I reverse engineered the electronics between the buttons and the control until. After that I installed a wi-fi based Raspberry-Pi computer and then I installed a peristaltic pump to add a little chlorine every day. Right now, I test chemical levels about once every 3-4 weeks. Generally I need to add di-chlor, to move the CYA levels back up and a little dry acid to move the pH down a bit. The system is very stable, I run the pumps about 2-3 hours a day and I only do that on cheap rate night electricity, which saves me about $75 a month on my electric bill. Basically I heat the hot tub to 105 or 106 in the morning and it's right about 103 when I want to go into it in the evening. I add about 50mL of chlorine a day, which is about 2 ppm in a 470 gallon hot tub. All the pump and chlorine scheduling is controlled by the Raspberry-Pi.

The current water is just over 2 years old, it has very high hardness levels (550) and is right on the edge of my ability to balance. I am about to dump and replace about half the water to get the hardness back down to a reasonable level. So I figure this means the water lasts about 4 years compared to the 3-6 months I used to get.

I started to write up a blog earlier this year which is at DIY: WiFi my Hot Tub. A lot of functionality has been added since I did that blog, which I have not written up yet.

Has anybody else out there built there own hot-tub controller, Do you measure the chlorine levels or just add some each day as I do. Is anybody out the adjusting pH automatically ?

Thanks to all those that have made this forum great and for providing the basis for me to have done this project.

Bruce
 

tmm1

Gold Supporter
Dec 21, 2018
25
Santa Barbara, CA
#2
Very cool!

I recently converted my spa to salt-water and am using the SmarterSpa system which has a chlorine monitor and kicks off the SWG when the chlorine levels fall below 1ppm. It works quite well, but I wish it was WiFi connected so I could record stats on how often it was running and when.

Hooking a rPi to the existing spa controls is a great idea. Do you know how similar the spa controller is across different spa makes and models?
 

dunginhawk

Bronze Supporter
Jul 10, 2018
252
CLIVE/IA
#3
Very cool!

I recently converted my spa to salt-water and am using the SmarterSpa system which has a chlorine monitor and kicks off the SWG when the chlorine levels fall below 1ppm. It works quite well, but I wish it was WiFi connected so I could record stats on how often it was running and when.

Hooking a rPi to the existing spa controls is a great idea. Do you know how similar the spa controller is across different spa makes and models?
I have a tub with SWG that I only finally realized wouldn’t kick in until i got over about 2500/2600ppm salinity. Now I’m actively making plenty, more or less to keep it self maintained from a sanitizer standpoint. I think i may have added 2 oz of chlorine over the last 4-5 soaks.

I would love to be able automate things, to have WiFi enabled sensors of chlorine etc.. i hate having to do multiple drop tests per day as I manage this thing. Luckily that’s about the only thing i test, the rest using TFP is super stable
 
OP
OP
B
May 23, 2016
5
Los Altos, CA
#4
Hi,

I'll have a look at the SmarterSpa system to see how it reads the chlorine levels.

> Do you know how similar the spa controller is across different spa makes & models ?

I don't really know as I have not taken any others apart. The Jacuzzi Hub I have uses a Sundance controller (I believe Sundance owns Jacuzzi) so I figure most of those are pretty similar in that I suspect they use a SPI serial interface. However, I bet the button codes and the information sent from the controller to the buttons for display (temperature for example) is a different format. I did start to pull my brother in laws Tub apart. His used a Balboa VS100 controller, which has a similar looking connection from the controller board to the buttons, so I guess it may be the same serial protocols, but I did not do an analysis yet, maybe sometime I will. Next time I try this, I'll use on of the Pi zeros, because they only cost $10.

Bruce