Sutro Shut Down: What Pool Owners Should Do Now

If your Sutro sensor stopped sending readings, or the app just won't open anymore, you're not imagining it and you didn't do anything wrong. Per public reports, Sutro's floating water-testing sensor, its companion app, and the subscription that tied them together were discontinued in 2025. Here's what that actually means for the hardware sitting in your pool, what you've lost access to, and a calm path back to a working routine that doesn't depend on any single company staying in business.

What happened to Sutro

Sutro sold a floating sensor that sat in the pool and took automated readings, chlorine, pH, alkalinity, and more, then sent them to a companion app over a required subscription. The device itself couldn't do anything on its own; it needed Sutro's backend to interpret readings and turn them into numbers and recommendations you could actually use. Per public reports, that backend and the app were discontinued in 2025, which means the sensor lost the service it depended on. Owners who'd already paid for the hardware were reportedly left with a device that could no longer deliver readings once the company's servers stopped running it. This is a known risk with any connected hardware: the physical object survives, but if it needs a company's server to function, it stops working the day that server goes dark.

Your migration path: from sensor to manual testing

• Retire the physical sensor. Without Sutro's backend, it has no way to take or transmit a reading, it's inert hardware at this point, and there's no official guidance we're aware of for repurposing it.
• Before the app disappears entirely, open it and screenshot or export anything you can, past readings, dosing history, equipment notes. Even a photo of a screen is better than nothing once access is gone for good.
• Pick up test strips or a liquid test kit as your new baseline. Either works; a liquid kit is generally more precise, test strips are faster and good enough for routine checks.
• Settle into a simple testing rhythm: a real water test roughly once a week, more often in hot weather or heavy pool use, since you no longer have a sensor checking automatically in the background.
• Choose where the resulting numbers will live going forward, a notebook, a spreadsheet, or a tracking app, before you're a month into manual testing with nowhere to put the results.

None of this requires becoming a chemistry expert overnight. You're just re-learning to do by hand what the sensor used to do automatically: check the water, write down the number, and adjust when something drifts. The ranges you're testing for haven't changed just because the hardware that used to read them for you has.

When you go looking for a replacement for the tracking side of things, it's worth being deliberate about what you pick, since the whole problem you're solving right now is a tool disappearing out from under you. Favor something that stores your data on your own device rather than exclusively in a company's cloud account, and that doesn't require an ongoing subscription just to keep functioning at all, that way losing the company doesn't mean losing the app's basic use. Skimmer, for example, has no backend and no required account: every reading, dose, and equipment note you log stays on your iPhone, so there's no server that can be turned off out from under you the way Sutro's was. It won't take automated readings for you the way a floating sensor did, that trade-off is real, but it also means the app you're using next year works exactly the same as it does today.