Wellis Crystal pH Down (1 L)

€15.00
Incl. VAT

Wellis Crystal pH Down is a precise pH-reducing chemical (sodium bisulphate). Lowers high pH levels in your spa water back into the 7.2–7.8 range where sanitisers are most effective and bathers are most comfortable.

Wellis Crystal pH Down (1 L)
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Wellis Crystal pH Down (1 L)

What it does

High pH (above 7.8) reduces chlorine effectiveness, causes scale on acrylic and equipment, and can irritate skin and eyes. Crystal pH Down brings pH back to neutral.

When to use

  • After a 5-in-1 test shows pH above 7.6
  • After fresh fill if your tap water is alkaline
  • After heavy bather load (high usage pushes pH up)

How to use

  1. Test water with Crystal Pool Check 5-in-1 strips — confirm pH is above 7.6.
  2. Turn the spa circulation pump ON.
  3. Add the dose printed on the bottle (per 1 m³ of water) directly to the spa, away from the skimmer intake.
  4. Run circulation for 15 minutes.
  5. Wait 2 hours, then retest.
  6. Repeat if pH is still high — never over-dose.

⚠ Important — please read before use: Always follow the dosing instructions printed on the product label and on the Safety Data Sheet (SDS) supplied with the chemical. Consult your Wellis spa user manual for product-specific water-care guidance applicable to your model, water source, and usage pattern. Never mix water-care chemicals together directly — always add each product separately to circulating spa water with the pump running. The information on this page is provided as general guidance only and does not replace the manufacturer's instructions or professional advice. TwoRelax accepts no liability for damage, injury, water-quality issues, or equipment failure resulting from incorrect use, improper dosing, mixing of incompatible products, or failure to follow the manufacturer's instructions.

Product Details

Manufacturer and Warranty Information

Shipping Details

  • Free curb side delivery or White-Glove delivery for a fee
  • Ships within 5-10 business days for products in stock
  • Ships within 30 business days for products made to order / out of stock
  • 14-day return window
  • View the Delivery & Returns Page for more information

Why Wellis Crystal Water Care?

Wellis Crystal is the same water-care system Wellis use to commission their factory test pools — engineered specifically for spa hardware.

Engineered for Wellis spas

Wellis Crystal chemistry is balanced for the materials Wellis use — acrylic shells, WPS frames, stainless components. No risk of staining or material degradation.

EU-manufactured, EU-shipped

All Wellis Crystal products are made in Hungary and shipped within the European distribution network. No transatlantic delays.

Compatible with most spas

While engineered for Wellis spas, the Wellis Crystal range works with most modern third-party spa brands — universal pH, alkalinity, and sanitiser chemistry.

HSG282-compliant

Wellis Crystal sanitiser products meet UK HSG282 spa-water standards — relevant for commercial use, holiday lets, and rental properties.

Frequently Asked Questions about TwoRelax and Wellis Crystal Water Care

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