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Best copper sulphate UK

Updated: 23 October 2026

You want one pack from this amazon.co.uk set, and best is doing too much work in that sentence. Inside these eleven listings, the lowest price per kilogram and the stronger large-sample star line are two different products, and both are still uncertified crystals. This page names them. It does not give a handling method or a footbath strength. Prices are the shelf figures in our [copper sulfate comparison](/hub/diy-supplies/copper-sulfate), not a live check on 20 October 2026. A qualifying purchase can earn us a commission at no extra cost to you. If you still need the decision rule before a name, use the [buying guide](/hub/diy-supplies/copper-sulfate/sub/copper-sulfate-buying-guide).

You want one pack from this amazon.co.uk set, and best is doing too much work in that sentence.

Our top picks

Minerals-water.ltd 500 g copper sulphate pentahydrate

Best overall

Minerals-water.ltd 500 g copper sulphate pentahydrate
8.8/10about £7.97
View offer
Minerals-water.ltd 250 g copper sulphate pentahydrate

Alternative

Minerals-water.ltd 250 g copper sulphate pentahydrate
8.6/10about £5.97
View offer
MAIGORAY 1 kg copper sulphate pentahydrate

Best value

MAIGORAY 1 kg copper sulphate pentahydrate
8.6/10about £7.97
View offer
On this page
  1. 1.Lowest price per kilogram
  2. 2.The large-sample 500 g pack
  3. 3.Packs that look better and are not
  4. 4.Who should skip the 500 g and the 1 kg

Lowest price per kilogram

The best value on price per kilogram is the 1 kg pentahydrate bucket at £7.97, 4.3 from 113 ratings, with CuSO4·5H2O printed. The brand line says MAIGORAY and the manufacturer line says Minerals-water. The assay line is high purity with no number. The signal word is Warning: harmful if swallowed, and skin and eye irritation. No MAPP number is in the file. The 500 g pouch is the same £7.97 for half the mass, about £15.94 per kilogram. The 250 g pack is about £23.88 per kilogram. The 5 kg tub is about £13.99 per kilogram. One UK review reports a dark precipitate and extra water and calls the pack unsuitable for crystal growing or water treatment. Other reviews call the price good value. A low price does not turn the bucket into reagent grade, and it does not authorise a plant-protection use.

The large-sample 500 g pack

The other pack this page names is the 500 g pouch, £7.97, 4.4 from 159 ratings. The title says pentahydrate. There is no numeric assay and no CLP word. It is the top pick on review evidence: the best star line among packs with more than a hundred ratings. It is not the largest sample. The 250 g listing has 188 ratings at 4.3, and it costs far more per gram. UK reviews mention plant scorch and insoluble residue, including scorched broad beans and a peach that lost its leaves. That is why this page will not call it the best quality. The comparison score is the amazon.co.uk star rating times 20, with a deduction when the sample is thin. It is not a laboratory score. If you need the most grams per pound, the 1 kg bucket is the better bargain.
Minerals-water.ltd 500 g copper sulphate pentahydrate

Testsieger

Minerals-water.ltd 500 g copper sulphate pentahydrate
8.8/10about £7.97
View offer

Packs that look better and are not

The 5 kg tub is £69.95, 4.5 from two ratings, with a minimum assay of 99.5% and no review text. About £13.99 per kilogram is a worse rate than £7.97, and the seller line about fungicide, footbath, and pool is not an authorisation. The listing titled 1,400 g is £17.97 and 4.6 from 15 ratings, while the item weight says 1 kg, so the rate might be about £12.84 or £17.97 per kilogram. The 4 oz pack is 3.8 from 22, near £172 per kilogram if 4 oz is 113 g, and its written reviews are from the United States. Lime kits are dry pouches, not loose-crystal picks.

Who should skip the 500 g and the 1 kg

Skip both if you need a certificate, an authorised plant-protection product, a pond biocide, a veterinary medicine, or food. Neither file prints a MAPP number. Warning on the 1 kg listing is weaker than the Fisher sheet for CAS 7758-99-8, signal word Danger. A missing CLP word on the 500 g pouch is not a milder chemical. Buy the 1 kg when pounds per kilogram decide it, and the 500 g when you want the stronger large UK star line and can pay about twice as much per gram.

Common questions

Which pack is the lowest price per kilogram in this set?
The 1 kg pentahydrate bucket at £7.97, which is £7.97 per kilogram. It has 4.3 from 113 ratings, formula CuSO4·5H2O, and the signal word Warning. The 500 g pouch is the same £7.97 for half the mass. The 5 kg tub is about £13.99 per kilogram. Small packs cost several times more per gram. This is the shelf price in the category file, not a promise that the live page never changes.
Which pack has a large UK review count, and is that the same as the most reviews?
The 500 g pouch has 4.4 from 159 ratings, which is the large-sample pack this page names with the 1 kg. The most ratings overall are on the 250 g pack, 4.3 from 188, at about £23.88 per kilogram. Most reviews and better stars among large samples are not the same sentence. Neither count is a purity test.
Is the 5 kg tub better value because it states 99.5%?
It states a minimum assay of 99.5%, which the 1 kg listing does not. It also costs about £13.99 per kilogram against £7.97, with 4.5 from two ratings and no review text. The assay is a seller line without a certificate in the file. A Fisher extra-pure 5 kg bottle at £145 is a different product. The 99.5% line does not make this tub the best value here.
The 1.4 kg listing is £17.97 and rated 4.6. Why is it not the pick?
The title says 1,400 g and the item-weight line says 1 kg, so the price per kilogram might be about £12.84 or £17.97. Fifteen ratings are a thin sample next to 113 and 159. Reviews mention missing directions, and there is no CLP block. The part number matches the cheaper 1 kg listing. Stars on an unsettled mass are not a reason to pay more.
Should I treat the 4 oz 99.9% title as the purest pack?
No. The title says 99.9% and a bullet says more than 99%, with no certificate. The rating is 3.8 from 22, the weakest star line in the set, and the written reviews in the file are marked United States. At £19.51 for about 4 oz you are near £172 per kilogram. A high percentage on a small, poorly rated pack is not a verified grade.

Related pages

Copper sulphate and lime

Copper sulphate footbath

Copper sulfate

Copper sulphate buying guide: hydrate, grams and job

Copper sulphate safety handling before you open it

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Listings stored 20 October 2026.

  1. HSE: garden and allotment pesticides (retrieved 20.10.2026)
  2. HSE: active substance register (retrieved 20.10.2026)
  3. HSE: amateur garden pesticide database (retrieved 20.10.2026)
  4. NHS: poisoning (retrieved 20.10.2026)
  5. GOV.UK: report water pollution (retrieved 20.10.2026)
  6. GOV.UK: pollution prevention for businesses (retrieved 20.10.2026)
  7. Fisher Scientific UK: copper(II) sulphate pentahydrate safety data sheet, part C/8520 (retrieved 20.10.2026)