Some thoughts on the Sutro system


Gold Supporter
Jul 15, 2012
East Hampton NY
Pool Size
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
I thought I would give it a try, though I am almost certain to return it after the trial period ends (they extended me from 60 to 90 days).

There is no replacing drop-based testing, but I thought the Sutro could be an early warning sign for low chlorine or sudden pH imbalances. Sutro uses a cartridge with capacity for about 90 tests (a mont worth). Their is a unit floating in my pool with the cartridge chemicals that sends messages to a hub, which in term sends to their server, which finally sends me updates. The Sutro sends a reading to my iPhone every 8 hours (that is the most frequent it can do) with FC, pH and TA. Unfortunately, the FC maximum reading is 5+, TA is only actually read once a day and [presented in a 30 point range, and most importantly, TA and [H are very frequently wrong. Sutro also provides their own recommendations with every reading on chemicals to add, but that assumes their readings are correct and that you want to maintain their pre-determined levels. Since they dont track CYN, it is not possible for their FC recommendation to have much meaning. Similarly, since they dont track CH, their pH target is kind of meaningless - even if their unit read the proper pH.

The FC readings have been pretty consistently 5+, as has my FC. On three occasions the Sutro detected lower chlorine - twice it was correct and once it was just a mistake. To its credit, the Sutro alerted me of an issue that I needed to correct (I had accidentally lowered the SWG too much) - and it did it on a day I was lax about testing. The pH readings and TA are all over the place. I am on my second cartridge - the first one had a calibration issue (it was slightly low all the time) but not a big deal. The second cartridge has been a dud for two weeks - my pool runs 7.8-8.0 and Sutro insists its anywhere from 6.7-7.2. They are sending me a new cartridge later this week, but it took me 4 different email complaints and I needed to fill out two forms before they agreed. They kept asking me if my test kit and pH meter were accurate.

Their service is also very irritating. They will not let you override the desired chemistry - that would be an easy fix. Instead they arrogantly tell you their computer can calculate the proper chemistry for your pool better than any human. Pure Crud. It is also impossible to communicate with higher level tech people. All I can do is receive daily emails (they read and respond once/day) with a call center in India, who refers your messages to more sophisticated people, so you are entrenched with low level middle men. I'd be happy to discuss the product with someone who wanted to improve what they offer, but Sutro has no desire to permit that communication.

I really do see a use for a product that does FC readings multiple times a day and sends alerts. The technology is clearly there, and this unit seems to read FC well (despite its 5+ ceiling). But the other bells and whistles like chemical recommendations and inaccurate pH and TA readings are more disturbing. Especially because pH can be read accurately electronically without chemical drop / color read (although periodic calibration is necessary). Unfortunately, this product is nowhere near ready for prime time, is not worth the $199 initial cost or the $29/month cartridge fee.
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