Cheap Ph Automation

[jparr]

My fill water has has a very high Ph and TA (8+/250+) so combined with a SWG, I am constantly adding acid to keep things in balance. I see there are a number of cheap Ph meters/controllers on eBay, marketed for the aquarium market. Would these reliably report Ph from pool water, with all the other chemicals we have in the water? I am envisioning connecting the relay output to a small pump that would introduce diluted MA to the pool water.

http://cgi.ebay.com/Milwaukee-Automated ... 2a0709fb5f

http://cgi.ebay.com/Weipro-Realtime-PH- ... 3a5e77f329

 

[Bama Rambler]

Looks like the first one isn't adjustable so it's not a good choice for a pool. The second one might be alright if you can adjust the setpoint to the mid sevens.

 

[JasonLion]

Typically you don't need a sensor/controller system when setting up an acid feed system. It is generally sufficient to make a system where you can manually control the rate at which acid is added. It is normally quite easy to adjust the system to an appropriate feed rate manually. You don't need to get the acid feed rate exactly right, you just need to get it in the right general range. That will then dramatically slow down the rate at which the PH changes, so that it becomes very easy to manually adjust the PH, say once a week, to take care of any error in the acid feed rate.