I have had this monitor for PH for a couple of years.. I have replaced the probe, but I was also able to clean the old one and get it back to reading within .2 with just a soap and water solution. I keep this in and on 24/7. After a certain time, it switches to only getting readings every 10 minutes so it saves on battery life.

https://www.amazon.com/dp/B08SJ7XFBY?psc=1&ref=ppx_yo2ov_dt_b_product_details

As for EC/PPM I use a Truncheon.. I check daily, just cause I am anal... It literally takes less than a minute...