Zodiac UV Blockout Chlorine Stabiliser 2kg – Pool Chemical
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Longer-Lasting Chlorine Under the Australian Sun
Zodiac UV Blockout is a fast-dissolving granular stabiliser for outdoor swimming pools. Commonly known as pool sunscreen, it protects chlorine from breakdown caused by direct sunlight.
Its cyanuric-acid formula supports a steadier sanitiser residual, helping chlorine remain active for longer between regular treatments.
Features & Benefits
- Protects chlorine from UV rays: Helps reduce sanitiser loss in outdoor pools.
- Fast-dissolving granules: Provides a practical way to raise or maintain the pool’s stabiliser level.
- Longer-lasting chlorine: Supports more consistent sanitiser performance between treatments.

How to Use
- Test the pool’s current cyanuric-acid level and calculate the required dose.
- For media-filter systems, clean or backwash the filter first, then add the granules through the skimmer basket while the pump is running.
- For cartridge-filter systems, dissolve the granules in a bucket of water before adding the solution to the pool.
- Run the pump for at least 8 hours after application.
- Do not clean or backwash the filter for 48 hours while the product dissolves.
Dosage & Coverage
- Dosage: Add 200g per 10,000 litres of pool water.
- Stabiliser increase: Raises the cyanuric-acid level by 20ppm.
Important Usage Information
- For most outdoor pools, maintain cyanuric acid between 30–50ppm.
- For pools using a chlorinator with an ORP probe, keep cyanuric acid below 20ppm and ideally as close to zero as practical.
- Do not allow the cyanuric-acid level to exceed 100ppm.
- Do not mix directly with chlorine or other pool chemicals. Add each product separately.
After treatment, continue regular water testing and maintain free chlorine at 2–4ppm and pH at 7.2–7.6. Keep Total Alkalinity at 80–120ppm for fully tiled, pebble and plaster pools, or 125–150ppm for vinyl and fibreglass pools.
A Better Pool Experience Starts with the Right Chemistry
Zodiac pool chemicals support the key parts of everyday water care, from balance and sanitising to algae prevention, clarity, stain control and equipment protection.
Each product has a clear role in helping pool water stay cleaner, more comfortable and easier to manage, so the pool feels ready to enjoy more often.

Frequently Asked Questions
How is UV Blockout different from UV Blockout Tablets?
Zodiac UV Blockout uses fast-dissolving granules to raise the pool’s cyanuric-acid level. Zodiac UV Blockout Tablets provide pre-measured 500g slow-release doses for convenient skimmer-box application.
Does Zodiac UV Blockout sanitise the pool?
No. UV Blockout is a chlorine stabiliser, not a sanitiser. It protects chlorine from sunlight but does not replace the chlorine required to sanitise the pool water.
Why should the cyanuric-acid level remain below 100ppm?
While cyanuric acid protects chlorine from sunlight, excessive levels can slow chlorine activity and make sanitiser control more difficult. High stabiliser levels usually need to be corrected by partially draining the pool and replacing the removed water with fresh water.
Why do ORP-controlled pools require less cyanuric acid?
ORP probes measure the sanitising activity of chlorine rather than the total free-chlorine level. Cyanuric acid binds with free chlorine to protect it from UV rays, but at higher levels this can reduce chlorine reactivity and lower the ORP reading. The control system may then respond by adding more chlorine in an attempt to reach its target reading, so cyanuric acid should be kept below 20ppm and as close to zero as practical in ORP-controlled pools.
Why should the filter be cleaned before adding UV Blockout?
Cyanuric-acid granules dissolve gradually. Cleaning or backwashing a media filter before treatment helps avoid the need for another filter clean during the following 48 hours, when undissolved product could otherwise be removed from the system.
Image shows product in new packaging design. Actual product received may vary while previous label design is being sold through.
| SKU | WPQBO2 |
|---|---|
| GTIN | 9317545298719 |
| Barcode | WC000427 |
| Brand | Zodiac |
| Model | WC000427 - UV Blockout 2Kg Box |
| Product Type | Pool Chemical |
| Shipping Type | Standard |
| Chemical Type | Stabiliser / Sunblock |
| Chemical Function | Chlorine Stabiliser, UV Protector |
| Active Constituents | Cyanuric acid: 1000g/kg |
Shipping
Same-day dispatch applies to orders received by 12.00 pm (AEST) during business days. Orders received after 12.00 pm and on weekends or public holidays will be dispatched on the next business day.
Delivery fees are $19.95 flat-rate per order Australia-wide, no matter how many products are in it. Orders containing bulky items like sand filters, acoustic boxes, heat pumps, pool covers, and pool slides may incur additional fees as they require specialized carriers.
Below are the estimated time to arrival in business days once an order is shipped.
| Destination | Sydney | NSW | VIC | QLD | SA | WA/NT |
|---|---|---|---|---|---|---|
| Business Days | 1 - 2 | 2 - 4 | 2 - 4 | 2 - 4 | 3 - 4 | 5 - 6 |
Rural and remote addresses, where delivery is not provided every day, may take longer.
Returns
Satisfaction Guarantee: If you are not satisfied with a product for any reason, you are welcome to return it to us for a full refund or exchange within 30 days of the purchase date - even if you have used the product. Returns are free, and we will cover return shipping.
We take full responsibility for the safe arrival of the products that you order from us. We will replace at our expense any product that arrives faulty, damaged during transit, or is the incorrect product. Click here for details
If you have any questions about our shipping policy or our return policy, please contact us on 1300 766 619 or through our contact us form.