FreshWater Ag+ Silver Ion Sanitizer | Hot Tub

• 1 × FreshWater Ag+ Silver Ion Sanitizer cartridge — main body containing the silver-impregnated media
• Attachment handle — clicks into the cartridge body to form the complete unit (two-part design)
• Manufacturer use and storage instructions — printed on the packaging

A typical residential spa uses one cartridge at a time. Replace every 4 months, or at every drain-and-refill — whichever comes first.

• ~4 months of continuous silver ion release — install and forget for the duration
• Dramatically reduces chlorine requirement — most owners cut their chlorine usage by 50–75% when using Ag+ alongside
• Less chlorine smell, less skin irritation, less swimsuit damage — the comfort upgrade most owners notice within a week
• Drops into the filter standpipe — installs in under a minute, no tools, no plumbing
• Works with multiple primary sanitizers — chlorine, MPS shock, FreshWater Salt System, Hot Spring ACE
• Two-part design — cartridge body + attachment handle snap together, then drop into the spa's filter standpipe
• 2-year sealed shelf life — can be stored unopened until needed
• Genuine Watkins Wellness — designed by the same team that builds Hot Spring, Caldera, Hot Spot, Solana, Tiger River, and Limelight spas
• EPA-registered — silver ion technology has decades of regulatory backing as a water sanitizer
• Reduces scum lines and odor — fewer organic byproducts when chlorine load is lower

The Ag+ cartridge contains a silver-impregnated media bed sealed inside a perforated plastic housing. When the cartridge is installed in your spa's filter standpipe, water flows through the housing continuously as your circulation pump runs. As water passes through the media, microscopic amounts of silver ions (Ag+) dissolve into the water.

Silver ions are antimicrobial — they disrupt bacterial cell membranes and interfere with bacterial reproduction at concentrations far below what would be detectable on skin or by smell. The result is a continuous low-level sanitizing effect that does not require chlorine to maintain.

Here's what's happening day to day:

• Silver ions are slowly released as water flows through the cartridge media
• Ions distribute throughout the spa water via the circulation system
• Bacterial growth is inhibited continuously — silver ions are still working even when the pumps are off (the water itself is "charged")
• You add chlorine or MPS periodically to handle organic contamination (body oils, sunscreen, sweat, lotion)
• Released ions are gradually consumed as they bind to organics and get filtered out — which is why the cartridge needs replacement every 4 months

The silver concentration in your spa water at any time is well below any health concern — the EPA limit for silver in drinking water is 100 ppb, and Ag+ cartridges release far less than that. You can drink municipal water with higher silver content than your spa will ever have.

Pro Tip: The cartridge has to be replaced at the 4-month mark even if your water still looks clear. The silver media depletes whether you can see it or not — and once it's spent, the cartridge is just a piece of plastic in your filter standpipe. Mark your calendar at install.

Installation (Fresh Fill)

1. Drain and refill your spa with fresh water.
2. Balance the water first — alkalinity 80–120 ppm, then pH 7.2–7.8, then calcium hardness as appropriate for your sanitizer system.
3. Super-oxidize the water — add dichlor at approximately 1.5 tablespoons per 250 gallons. Run all pumps for at least one full cycle (typically 15–30 minutes). This burns off any residual contamination from the fill and activates the cartridge.
4. Wait until chlorine drops below 5 ppm — do not enter the spa or install the cartridge while chlorine is above this level.
5. Assemble the cartridge — attach the handle to the main body until it clicks into place.
6. Remove the gray cap from the top of your filter standpipe.
7. Drop the cartridge into the standpipe with the handle facing up. It should seat naturally.
8. Replace the gray cap over the standpipe.
9. Note the install date on your calendar or phone for the four-month replacement reminder.

Ongoing Water Care With Ag+ Installed

• Maintain a small chlorine residual — typically 1–3 ppm. The Ag+ handles continuous bacterial inhibition; the chlorine handles organic oxidation.
• Shock weekly with dichlor or MPS — light dose, just enough to oxidize the past week's bather load.
• After heavy use (parties, multiple soakers), shock more heavily — 2–3 tablespoons of dichlor per 250 gallons. Wait for chlorine to drop below 5 ppm before re-entering.
• Test water weekly with FreshWater 5-Way Test Strips. Adjust pH and alkalinity as needed.
• Do NOT add bromine — the Ag+ program is chlorine-based.

Replacement Schedule

• Every 4 months under normal use
• At every drain-and-refill — whichever comes first
• Sooner if you notice persistent cloudy water or chlorine demand that climbs sharply (the silver may be depleted)

Storage of Unused Cartridges

• 2-year shelf life when kept in original sealed packaging in a cool, dry location
• Do not store in the spa cabinet — heat and humidity can degrade the silver media even when unused
• Keep away from direct sunlight

Pro Tip: The biggest mistake owners make with Ag+ is skipping the regular dichlor or MPS shock once they see the chlorine smell drop. Without periodic oxidation, organic load builds up — water gets cloudy, foam appears at the surface, and eventually the silver ions get bound up neutralizing organics they were never meant to handle. A small weekly shock keeps the system performing as designed.

• Brand: FreshWater® (Watkins Wellness)
• Manufacturer Part Number / SKU: 80010 (current packaging) / 71325 (legacy packaging) — identical product
• Quantity: 1 cartridge (single)
• Active Component: Silver-impregnated media (releases positively-charged silver ions, Ag+)
• Function: Continuous bacterial inhibition via silver ion release; supplemental sanitizer
• Lifespan: Approximately 4 months in a typical residential spa
• Annual Requirement: 3 cartridges per year on the standard schedule
• Cartridge Design: Two-part (main body + attachment handle); assembles in seconds
• Installation: Drops into filter standpipe; owner-installable, no tools required
• EPA-Registered: Yes
• Compatible Primary Sanitizers: Chlorine (dichlor), MPS, FreshWater Salt System, Hot Spring ACE, ozone systems
• NOT Compatible With: Bromine, biguanide (Soft Soak / Baqua Spa)
• Compatible Spa Brands: Hot Spring, Tiger River, Hot Spot, Solana, Limelight, Caldera
• Shelf Life Sealed: 2 years when kept dry and in original packaging
• Hazmat Classification: Non-hazmat — eligible for mail return per standard policy
• Country of Origin: Manufactured for Watkins Wellness, USA

The Ag+ Silver Ion Sanitizer is designed to drop into the filter standpipe of compatible Watkins Wellness spas. Fitment is broad — it works across most Hot Spring brand families from 1990 onward.

Compatible Spa Brands

• Hot Spring® — all collections (Highlife, Limelight, Hot Spot, TX, SX) from 1990 forward
• Tiger River® Spas — 1992 forward
• Hot Spot® Spas — 1998 forward
• Solana® Spas — 1998 forward
• Limelight® Spas — all models
• Caldera® Spas — most models

If you're not sure whether your spa is compatible, the simplest test is the filter standpipe: if your spa has a gray cap that lifts out of the top of the filter compartment, the Ag+ cartridge is designed to drop in beneath that cap. Older spas without a standard standpipe may not accept it.

Compatible With These Primary Sanitizers

• Chlorine (dichlor) — the most common pairing
• MPS (non-chlorine shock / potassium peroxymonosulfate) — reduces chlorine smell even further
• FreshWater® Salt System — reduces the workload on the salt cell, extending cartridge life
• Hot Spring® ACE® Salt Water System — same benefit as FreshWater Salt
• Ozone systems (FreshWater III, etc.) — Ag+ stacks well with ozone for a comprehensive water care setup

NOT Compatible With

• Bromine systems — silver ions and bromine chemistry don't play well together; Ag+ should never be used in a brominated spa
• Biguanide systems (Soft Soak / Baqua Spa) — biguanide kills the bacteria silver ions were going to handle anyway; no benefit, and possible interaction with biguanide stabilizers
• Spas without a standard filter standpipe — the cartridge needs the standpipe to hold position; off-brand spas without compatible filter housings can't use this product

Works Alongside

• FreshWater Concentrated Chlorinating Granules — the small dichlor dose used for periodic oxidation
• FreshWater MPS Test Strips — if running an MPS-based program alongside Ag+
• FreshWater 5-Way Test Strips — for verifying chlorine residual stays in the proper range
• FreshWater Stain & Scale Defense — protects against scale buildup that can clog filter media around the cartridge

Pro Tip: If you're switching from bromine to a chlorine + Ag+ program, you need to fully drain and refill the spa first. Residual bromine in the water will compete with the silver ions and cause both to underperform. Don't try to convert mid-fill.