FreshWater MPS Test Strips | Non-Chlorine Shock

• 1 bottle of FreshWater MPS Test Strips — 50 strips in a sealed, moisture-resistant flip-top container
• Color-match comparison chart — printed on the back of the bottle, calibrated for MPS, pH, and alkalinity readings
• Desiccant pack — sealed inside the bottle to keep remaining strips dry between uses
• Manufacturer use and storage instructions — printed on the label

• Tests three parameters at once — MPS oxidizer level, pH, and total alkalinity
• 2-second dip time — fastest read of any FreshWater test strip
• Color-match chart on the bottle — no app, no booklet to lose
• Universal sanitizer system compatibility — works with FreshWater Salt, ACE, silver ion, granular chlorine, bromine, and any program using MPS as an oxidizer
• 50 strips per bottle — approximately a year of weekly testing
• Sealed bottle with desiccant — strips stay accurate through the full pack when the cap is closed promptly
• Made by Watkins Wellness — calibrated to the same MPS targets the manufacturer specifies for its water care methods
• Designed for MPS-based programs — fills a specific testing need that 5-Way strips don't cover

FreshWater MPS Test Strips have three reagent pads, each calibrated for a different parameter. When dipped in spa water, the pads react with specific chemical markers and change color:

• MPS pad — reacts with active monopersulfate, shifting through a color range that maps to ppm
• pH pad — shifts through orange, red, and purple based on water acidity
• Total Alkalinity pad — shifts from yellow through green based on buffering capacity

After the brief 2-second dip, all three pads develop their color in seconds. Match the pad colors to the chart on the bottle to read your levels.

Why test for MPS specifically: unlike chlorine, which dissipates predictably over hours, MPS levels can drop quickly during heavy use — a single intense soaking session can deplete MPS faster than you'd expect. Without testing, you can end up oxidizing nothing for days at a time and assume the program is failing when it's just under-dosed. The MPS reading tells you when to add more shock.

Target ranges:

• MPS: 5–10 ppm (varies slightly by manufacturer; reference your water care guide)
• pH: 7.2–7.8
• Total Alkalinity: 80–120 ppm

Pro Tip: MPS readings can be affected by oxidizers in the water beyond just MPS — including residual chlorine, bromine, and even high levels of dissolved oxygen from aeration. If your reading seems higher than expected after a soaking session, recheck after 24 hours of normal circulation. The reading often settles into expected ranges as other oxidizers clear.

Testing Your Water

1. Remove one strip from the bottle and reseal the cap immediately. Moisture in the bottle is the most common cause of expired strips.
2. Immerse the strip in the spa water for 2 seconds.
3. Remove the strip with the pads facing up.
4. Shake the strip once to remove excess water.
5. Hold the strip horizontally (pads facing up) for a few seconds while colors develop.
6. Compare each pad to the chart on the back of the bottle. Read in good light, away from direct sunlight or harsh shadow.
7. Record the reading or photograph it for reference.

How Often to Test

• Weekly as part of routine water testing for most MPS-program owners
• After every shock dose to confirm MPS reached the target range
• After heavy use — multiple bathers, parties — to confirm the program is keeping up with oxidation demand
• Anytime water looks cloudy or smells "off" — low MPS is often the cause in non-chlorine programs
• Before every shock decision — confirm whether you actually need to dose more MPS or whether existing MPS hasn't been depleted yet

Interpreting Your Reading

• MPS below 5 ppm — dose more MPS (FreshWater MPS Shock Oxidizer or similar)
• MPS 5–10 ppm — proper range. No action needed.
• MPS above 10 ppm — typically fine for short periods, but high concentrations can be irritating to eyes and skin during use; wait for natural decay before soaking
• pH outside 7.2–7.8 — adjust with pH/Alkalinity Up or Down
• Alkalinity outside 80–120 ppm — adjust with pH/Alkalinity Up or Down

Storage

• Keep the bottle tightly closed between uses
• Store at room temperature, away from direct sunlight, humidity, and chemical fumes
• Do not store in the spa cabinet or any location that gets damp
• Note the expiration date printed on the bottle. Strips typically remain accurate for 1–2 years from manufacture if stored correctly.
• Never touch the reagent pads with wet fingers, and never return an unused strip to the bottle.

Pro Tip: If you're running an MPS + Ag+ (silver ion) program, MPS depletion is the #1 cause of cloudy water in those spas. The silver ions handle bacterial inhibition but produce no oxidation. When MPS drops too low, organic load accumulates and water turns cloudy regardless of how the rest of the chemistry looks. Test MPS first when troubleshooting cloudy water on a non-chlorine program.

• Brand: FreshWater® (Watkins Wellness)
• Manufacturer Part Number / SKU: 80091
• Quantity per Bottle: 50 strips
• Dip Time: 2 seconds
• Parameters Tested: MPS (monopersulfate), pH, total alkalinity
• Target MPS Range: 5–10 ppm
• Target pH Range: 7.2–7.8
• Target Alkalinity Range: 80–120 ppm
• Sanitizer Compatibility: FreshWater Salt, ACE, Ag+ Silver Ion, granular chlorine, bromine, ozone, biguanide — any program using MPS as primary or secondary oxidizer
• Spa Compatibility: All residential hot tubs, spas, and swim spas regardless of brand
• Not For Testing: Chlorine, bromine, salt level, calcium hardness, phosphates (use the appropriate dedicated FreshWater strip for each)
• Container: Sealed plastic bottle with flip-top cap and desiccant
• Shelf Life: Typically 1–2 years from manufacture date (see bottle for expiration)
• Hazmat Classification: Non-hazmat — eligible for mail return per standard policy
• Country of Origin: Manufactured for Watkins Wellness, USA

FreshWater MPS Test Strips are designed for any spa using MPS (potassium monopersulfate) as an oxidizer in its water care program. MPS appears in many sanitizer systems either as the primary oxidizer or as a periodic shock product.

Designed For

• FreshWater® Salt System — when used with MPS oxidation alongside salt-generated chlorine
• Hot Spring® ACE® Salt Water System — same as FreshWater Salt
• FreshWater Ag+ Silver Ion Sanitizer programs — Ag+ + MPS is a common low-chlorine pairing
• Chlorine programs using MPS for periodic shock — instead of using dichlor for shock
• Bromine programs using MPS for periodic shock
• Ozone systems — when MPS supplements ozone for oxidation residual
• Any program using MPS as the primary or secondary oxidizer

Spa Brands

• All residential hot tubs and spas running an MPS-based water care program — Hot Spring, Caldera, Freeflow, Sundance, Bullfrog, Jacuzzi, Marquis, Master Spas, Cal Spas, and every other major brand
• Swim spas using MPS oxidation
• Inflatable and portable spas on MPS programs

Not For Testing

• Chlorine residual — use FreshWater 5-Way Test Strips
• Bromine residual — use FreshWater 5-Way Test Strips
• Total hardness / calcium hardness — use FreshWater 5-Way Test Strips
• Salt level — use FreshWater Salt Test Strips
• Phosphates — use FreshWater Phosphate Test Strips

Works Alongside

• FreshWater MPS Chlorine-Free Shock Oxidizer — the product this strip tells you when to dose
• FreshWater 5-Way Test Strips — for chlorine, bromine, and hardness (essential paired test if you also have a chlorine or bromine residual)
• FreshWater Salt Test Strips — if running an MPS + Salt System combo
• FreshWater pH/Alkalinity Up & Down — for correcting readings outside the proper ranges
• FreshWater Ag+ Silver Ion Sanitizer — the most common companion to MPS programs