Ah, pool maintenance. The soothing act of pretending you understand water chemistry while tossing in chemicals like you’re seasoning a pot of chili. Add a little pH Up here, sprinkle some chlorine granules there, and boom—your pool still smells like a bleach factory with the mysterious film of “don’t ask” floating near the deep end.
But then along came Card On Guard and Crystal Smart Water Monitor, two bits of pool tech that practically begged to be called “cool” just for existing. So I decided to see if they could make my pool experience less like a science experiment gone wrong and more like a leisurely backyard escape. Spoiler: one of them did. The other? Let’s say it tried hard.
The Chlorine Whisperer: Card On Guard
I’ll admit, I didn’t expect much from a plastic tube that looks like it belongs in a science fair project about sunlight and bottle rockets. But the Card On Guard FIN promised me less chlorine, no power cords, and no need to rewire my plumbing. So naturally, I threw it into the deep end with all the hope and none of the expectations.
This gadget uses some patented UV Light Conversion Film—because apparently, we’re living in the age of BioPhotonX sorcery. It breaks down water molecules with sunlight and somehow creates free radicals (allegedly the good kind) that help chlorine work smarter, not harder. Or so says the marketing.
I tested the FIN in my pool, which usually drinks chlorine like it’s on a bender. After a week? Still clean. After three? Still clean…and notably less chemical-y. I didn’t feel like I was soaking in a vat of sanitizer, and my skin didn’t feel like I exfoliated with sandpaper. Progress.
For hot tubs and kiddie-pool-sized setups, there’s a TUBE version starting at $39. Larger pools can use the FIN—each one covering 15,000 gallons for $59. You’ll need one FIN per 15,000 gallons, so if you have a pool large enough to host an Olympic trial, budget accordingly.
The best part? No app, no electricity, no explosions. Just solar-powered chemical reduction magic. Honestly, it’s the laziest pool upgrade I’ve ever installed, and I respect that.
Crystal Smart Water Monitor: Big Brother, But For Chlorine
And now for the techier option: the Crystal Smart Water Monitor—because who doesn’t want a tiny robot yelling at them about water quality 1,000 times a week?
This little, floaty Wi-Fi friend monitors your pool 144 times per day, provides custom chemical dosing recommendations, and sends push notifications when your water is problematic because nothing says summer relaxation like getting alerts that your pool’s “free chlorine level has dropped below ideal range” while you’re trying to nap.
At first, I loved the idea: scan your chemical brands, get accurate readings, ditch the test strips. Finally, no more trying to decode a rainbow of mystery colors with questionable accuracy. I was excited. And then I remembered I’d just adopted an AI pool supervisor.
Don’t get me wrong, the data was spot on—probably too spot on. Crystal knew everything. It even told me my alkalinity was high before I remembered I needed to test it. I began to worry that it knew what I ate for breakfast.
Setup was easy-ish. The app works with both Android and iOS (a minor miracle in itself) and features some decent user experience. The first year of service is included, which is thoughtful, much like when a dealer gives you a complimentary first taste. After that, it’s $99 a year if you want to keep your aquatic overlord sending helpful texts.
There’s no need for brand loyalty, either. You can use any chemical brand you like without being locked into a subscription box from PoolCorp MegaConglomerate. And it supports saltwater systems, so the salty among us can relax.
Final Verdict: One Floats, One Overfunctions
If you want peace, quiet, and a subtle improvement in water quality, Card On Guard is your solar-powered spirit animal. You toss it in, ignore it, and it rewards you by making your pool a gentler, less toxic place to exist. It’s cheap, effective, and doesn’t require an engineering degree to operate.
If, however, you like graphs, data, and being micro-managed by your pool, then Crystal Smart Water Monitor will be your chlorine-obsessed best friend. It’s tech-heavy, accurate, and a little clingy—but in a “your pH is 7.3, great job!” kind of way.
In the end, I kept them both. Because if my pool’s going to judge me, it might as well be crystal clear while doing it.