Pool water monitor comparison

ICO vs WaterGuru SENSE S3

Do you want one broad chemistry test a day—or a monitor that watches the water every hour?

By Brian Williamson, Pool Express product specialist Published November 4, 2026

Winner: ICO Pool

I would buy ICO for most pools. WaterGuru gives you a direct free-chlorine result, but ICO watches the water 24 times a day, does not consume a test pad, measures salt on the Salt model, and lets me replace each sensor separately.

Why I'd choose ICO

Hourly readings without cassettes or test pads
ICO Salt measures salt and TDS
Floats or sits in the skimmer out of the box
Individually replaceable sensors with public prices

Where WaterGuru S3 has an edge

Direct free-chlorine result
C5+ cassette also reports alkalinity, CYA, and calcium hardness

See ICO Pool View every comparison

My pick

ICO Pool

$449 chlorine/bromine · $499 salt · 24 automatic readings a day

WaterGuru SENSE S3

$399 with one C5+ cassette · one scheduled chemistry test a day

The simple comparison

What matters	ICO Pool	WaterGuru S3
Starting price	$449 chlorine/bromine · $499 salt	$399 with one C5+ cassetteEdge
Automatic testing	Every hour · 24 readings a dayEdge	One scheduled test a day
Core measurements	pH, ORP, temperature · salt/TDS on ICO Salt	Free chlorine, pH, alkalinity, CYA, calcium hardness with C5+
Required test refills	NoneEdge	Cassettes · $76 per 3-pack
Connection	Direct 2.4 GHz Wi-Fi + Bluetooth	Direct 2.4 GHz Wi-Fi + setup Bluetooth
Battery	USB-rechargeable · 6+ monthsEdge	Solar + USB-C backup · about 5 months in full shade
Placement	Floats or sits in the skimmerEdge	Skimmer-mounted · float ring costs $29
Serviceability	pH, ORP, and TDS sensors sold separatelyEdge	No user-replaceable electronics verified

WaterGuru and ICO take two very different approaches. WaterGuru behaves like an automatic test kit: once a day, a cassette pad runs a broad chemistry test. ICO behaves like a true monitor: it follows pH, sanitizer performance, and temperature every hour without using a pad.

My take

I understand WaterGuru's appeal. Seeing a direct free-chlorine number is familiar, and its C5+ cassette also reports alkalinity, CYA, and calcium hardness. If that single daily report is exactly what you want, WaterGuru has the better chemistry snapshot.

I still prefer ICO. Pool water can change after a storm, a hot afternoon, or a crowded swim. Twenty-four readings show me the direction of the water, not just one moment. I also do not love the idea that checking again uses another paid test pad.

Cost over time

WaterGuru starts $50 below the chlorine/bromine ICO, but the cassettes change the math. A C5+ cassette handles 32 daily tests, and a three-pack costs $76. At one test every day, that is roughly $289 a year. The simpler C2+ cassette costs less per year but only reports free chlorine and pH.

ICO does not use test cassettes. It does require a $49 calibration kit at the start of each season (or every six months for a year-round pool), and its probes eventually wear out. I prefer that model because I am paying to maintain durable sensors, not buying a new test pad every day.

What they measure

WaterGuru wins on direct free chlorine and the breadth of its once-daily C5+ test. ICO measures pH, ORP, and temperature each hour. ORP is not a free-chlorine reading; it shows how effectively the sanitizer is working. ICO Salt also measures salt and TDS, while WaterGuru can live in a salt pool but does not tell you the salt level.

This is the real choice: a broader daily test or a continuous trend. For how I manage a pool, the trend is more useful most days, and I can confirm the occasional full chemistry panel with a good manual test.

Everyday ownership

Both connect directly to 2.4 GHz Wi-Fi and both have free apps. WaterGuru belongs in a standard eight-inch skimmer; another skimmer shape needs an adapter, and floating it requires a $29 ring. ICO floats or sits in the skimmer as sold.

The long-term parts story also favors ICO. Its pH, ORP, and TDS probes are separate $149 parts, so I can replace the one that ages. WaterGuru sells cassettes and mounting accessories, but I could not verify user-replaceable electronics or a battery.

Final call

My winner is ICO Pool. WaterGuru is the better fit for someone who values a direct free-chlorine result above testing frequency and ongoing cartridge cost. I would rather have hourly trends, no per-test consumable, salt measurement on the Salt model, and a monitor I can repair one sensor at a time.

See ICO Pool and choose your water type →

Common questions

Does WaterGuru have a subscription?

The app does not require a subscription, but the SENSE S3 needs refill cassettes to run chemistry tests. That is a consumable cost rather than an app fee.

Can WaterGuru measure salt?

No. It can be used in salt pools up to the published limit, but it does not report salinity. ICO Salt measures salt and TDS every hour.

Is WaterGuru ever the better choice?

Yes. Choose WaterGuru if a direct daily free-chlorine reading and the extra C5+ chemistry values matter more to you than hourly trends and cartridge-free operation.