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Copper free winter algaecide or a copper winteriser

Updated: 21 October 2026

Blonde hair has come out of the pool green, and the bottle you are about to order may or may not contain copper. A copper free winter algaecide is the listing that says those words. A copper winteriser is the listing that says copper. Several Amazon bullets in this set say neither, which is the gap that causes the wrong blame. This page is that metal question. The rows are on the [pool winteriser comparison](/hub/pool-care/pool-winteriser). Peter F. used the Fi-Clor hair sheet, brand pages, and the amazon.co.uk bullets as saved on 19 October 2026. We did not test hair or stains. A qualifying purchase can earn a commission at no extra cost to you.

Blonde hair has come out of the pool green, and the bottle you are about to order may or may not contain copper. A copper free winter algaecide is the listing that says those words.

Our top picks

Kleen Pool Kleen Pool algaecide, 1 L

Best overall

Kleen Pool Kleen Pool algaecide, 1 L
7.5/10about £17.95
View offer
Blue Horizons Blue Horizons winter time algaecide, 5 L

Rank 2

Blue Horizons Blue Horizons winter time algaecide, 5 L
8.6/10about £29.20
View offer
Relax Relax Winter Long, 1 L

Alternative

Relax Relax Winter Long, 1 L
5.8/10about £17.50
View offer
On this page
  1. 1.What actually tints hair
  2. 2.What the bottles in this comparison say
  3. 3.When a copper product is the wrong pool
  4. 4.How to choose

What actually tints hair

Fi-Clor's UK sheet attributes green hair to overdosed copper algaecides or to low pH corroding copper fittings, not to a dye in the chlorine. It suggests a vinegar rinse, a copper-free algaecide if hair is sensitive, a sequestrant, and pH about 7.2–7.6. Do not average that band with a winteriser label that prints a different one. Avoiding the word chlorine does not avoid copper. A case report also notes that not every green tint is proven copper in the hair shaft. Stains and blonde hair are still reasons to prefer a label that says copper free.

What the bottles in this comparison say

Only two listings print a copper line. Relax, about £17.50, says organo-copper, spelled Cooper. If you are avoiding copper, leave it. Blue Horizons winter time, about £29.20, says copper free. One UK review was still green in February. That line is about the metal, not a promise of clear water. The other seven are silent. Ultimate's sheet and HTH's brand page say non-copper or copper-free. Those Amazon bullets do not. Water Technics describes KleenPool as copper. The Amazon title does not. Pack size stays on the pool winteriser buying guide.
Kleen Pool Kleen Pool algaecide, 1 L

Testsieger

Kleen Pool Kleen Pool algaecide, 1 L
7.5/10about £17.95
View offer

When a copper product is the wrong pool

Water Technics says avoid copper products with biguanide, and with copper or silver ionisers. Relax on a biguanide pool is the combination those notes say to skip. A sequestrant does not replace a copper-free product. Relax is the declared copper bottle, and overdosing is the Fi-Clor failure mode.

How to choose

Prefer the listing that says copper free when stains, blonde hair, a copper fitting, or a biguanide pool already worry you. On Amazon that sentence is Blue Horizons winter time. The listing that says copper is Relax. Do not merge a silent Amazon bullet with a brand sheet. Relax is cheaper and it declares copper. Cheap is not copper free. Who should skip a bottle for other reasons is best pool winteriser UK.

Common questions

Does chlorine dye blonde hair green?
Fi-Clor's UK sheet says no. It attributes green hair to overdosed copper algaecides or to low pH corroding copper fittings, and it suggests a vinegar rinse, a switch to a copper-free algaecide if hair is sensitive, a sequestrant, and pH about 7.2–7.6. Chlorine is still the sanitiser many of these pools use. On that sheet it is not the dye. A case report also notes that not every green tint is proven copper in the shaft.
Which listing says copper on Amazon?
Relax Winter Long, ASIN B013WXBCXA, 1 litre at about £17.50. The bullets say copper based and organo-copper, spelled Cooper, and 14,500 liters. Blue Horizons winter time, B075DJDLQT, 5 litres at about £29.20, is the one that says copper free. The other seven kept listings do not print copper or copper free. A 4.0 from one Relax review, with no text saved, does not show how that copper behaved.
If the brand PDF says copper-free and Amazon does not, what can I say?
You can say the brand page says copper-free and the Amazon bullet does not. HTH's product page says copper-free. The amazon.co.uk listing for the 3 litre pack does not. Blue Horizons Ultimate's sheet says non-copper with a sequestrant. The Amazon bullets do not say copper free and do not print the sheet's dose. Shop the page you are paying on.
Is organo-copper still copper?
Yes, on the Relax listing. The bullets say copper based algicide and organo-copper complex. That is the copper declaration in this set, not a copper-free formula with a technical name. If you wanted to avoid copper stains or green hair, skip that organo-copper bottle, even at about £17.50.
What about a biguanide pool?
Water Technics says avoid copper products with biguanide, and with copper or silver devices. Relax is the Amazon listing that declares copper, so it is the poor match for that pool. A copper-free line, where the bullet actually says it, is the side those notes point to. Do not assume Kleen Pool is safe for biguanide. The trade sheet describes KleenPool as copper, and silence is not an approval.
Will a sequestrant replace a copper-free product?
No. A sequestrant is part of the response when copper is already in the water, on the Fi-Clor sheet, and it is paired with a non-copper description on the Ultimate brand sheet. It does not turn a declared copper algaecide into a copper-free one. On Amazon, only the Blue Horizons winter time bullet both says copper free and says it prevents staining and scale. Ultimate says stains and scale and does not say copper free.
Who should avoid copper even if the bottle is cheaper?
Anyone with stains, blonde hair that has already tinted, a copper fitting, a biguanide sanitiser, or a copper or silver ioniser. Relax at about £17.50 is cheaper than Blue Horizons winter time at about £29.20 and it is the listing that says copper. The saving is real only if copper is acceptable in your pool. If it is not, the cheaper bottle is the wrong product.

Related pages

How to use a pool winteriser

Pool winteriser

How to winterise an above ground pool safely in the UK

Best pool winteriser UK: which listing fits your pool

Swimming pool winteriser: the checks before you buy

Sources

Public UK sources used for this page in October 2026. Shelf prices and star lines are the amazon.co.uk figures for these nine listings, dated 19 October 2026.

  1. HSE: Biocidal product authorisation (retrieved 21 October 2026)
  2. HSE: Managing health and safety in swimming pools (HSG179) (retrieved 21 October 2026)
  3. HSE: Swimming pools (retrieved 21 October 2026)
  4. PWTAG: Microbiological testing TN53 (retrieved 21 October 2026)
  5. Lo-Chlor: Winteriser algaecide tech sheet (retrieved 21 October 2026)
  6. Blue Horizons Ultimate winteriser sheet (retrieved 21 October 2026)
  7. Water Technics: Swimming pool winterising guide (retrieved 21 October 2026)
  8. HTH: Super Winterprotect 3 L (retrieved 21 October 2026)