The best copper sulfates, compared.
Top pick: Copper sulphate and lime kit, 10 L title Best value: 1 kg copper sulphate pentahydrate – £7.97 for 1 kg of stated pentahydrate, the lowest price per kilogram among packs with at least 50 ratings. Updated 22.10.2026.
Copper sulfate on amazon.co.uk is usually sold as copper sulphate pentahydrate, the blue crystal, or as two dry kits of copper sulphate and hydrated lime. You are choosing a stated hydrate, a pack mass, and a price per kilogram. You are not choosing an authorised garden product. None of the eleven listings prints a MAPP number. The top pick is the 500 g Minerals-water.ltd pouch at £7.97, with 4.4 from 159 ratings. Best value is a different pack: the 1 kg bucket at the same £7.97, with CuSO4·5H2O printed, the signal word Warning, and 4.3 from 113 ratings. How to read hydrate, an assay claim, and a missing authorisation is set out in the [copper sulfate buying guide](/hub/diy-supplies/copper-sulfate/sub/copper-sulfate-buying-guide). A Fisher Scientific safety data sheet for the pentahydrate uses the signal word Danger: harmful if swallowed, serious eye damage, and very toxic to aquatic life with long lasting effects. If a listing has no CLP word, treat that stricter class as the one to plan around. Store the pack closed, dry, and away from children, pets, and food. A title that mentions plants, a pond, or a footbath is seller wording, not permission to use the salt that way.
Copper sulfate on amazon.co.uk is usually sold as copper sulphate pentahydrate, the blue crystal, or as two dry kits of copper sulphate and hydrated lime.
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Personal buying guide
Question 1 of 2
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The 10 L title sits on a unit count of 200 g, four items, and two packs of pre-measured 50 g pouches, at £14.97. The star line is 5.0 from a single rating with no review text, so that perfect score is one click, not a tested result. Hydrate, assay, CLP, and a MAPP number are all absent. A listing question asks whether preparation is easy. The bullets say separate pouches simplify preparation, and no review confirms that. The image URL in the file matches the 5 L kit. At £14.97 you pay £5 more than the 100 g kit for a larger title and a doubled unit count. You still have no evidence of an authorised product. Skip it when you need review text or a stated pentahydrate crystal mass.
Pros
Cons
Best for: You already understand these are dry pouches and you are only comparing the 200 g unit count with the 100 g kit.
Less suitable: You want review text, loose crystals, or a ready product with a MAPP number.
Specifications
Common questions
What do the counts say?
The title says 10 L. The unit count is 200 g. Number of items is 4. Number of packs is 2. Bullets say pre-measured 50 g pouches of each component, supplied separate.
Does the listing print a measured preparation?
A listing question asks if preparation is easy. The bullets say separate pouches simplify preparation. No review text confirms that. The rating line is 5.0 from 1.
Is a MAPP number printed?
No. There is no CLP block. The image URL in the saved listing matches the 5 L kit.
Birsppy’s title says 1,400 g of pentahydrate while the item-weight line says 1 kg, both sitting on a £17.97 price with 4.6 from 15 ratings. The formula CuSO4·5H2O and a molecular weight of 249.68 are printed, and part number 5060374640528 matches the 1 kg listing, so this may be a related pack under a different ASIN rather than a clearly heavier tub. There is no numeric assay and no CLP block. Reviews mention missing directions, and a later email was unclear. Fifteen ratings are a short sample next to 113 on the £7.97 kilogram. If the contents are 1.4 kg the rate is about £12.84 per kilogram. If they are 1 kg it is £17.97 per kilogram. Buy it only after you have confirmed which mass will arrive.
Pros
Cons
Best for: You have already checked which mass this ASIN will send and you want the formula line in the listing.
Less suitable: You need one agreed mass, or the £7.97 kilogram with 113 ratings.
Specifications
Common questions
How much does the listing say is in the pack?
The title says 1,400 g. The item-weight line says 1 kg. Both are printed. The manufacturer part number matches the 1 kg listing. The ASINs stay separate.
Is a formula printed?
Yes. CuSO4·5H2O, with a molecular weight of 249.68. There is no numeric assay and no CLP block.
What do the reviews say about instructions?
One review says the pack had no directions. A later email was unclear. The listing line is 4.6 from 15 ratings.
SOW 'N' GROW sells 5 kg of pentahydrate in a resealable tub at £69.95, and a bullet states a minimum assay of 99.5%. The star line is 4.5 from only two ratings, and the file has no review text, so the assay is a seller claim without buyer notes here. A bullet names cattle footbaths and warns that excess copper can stain a pool and create a risk for swimmers. There is no CLP signal word and no MAPP number. At about £13.99 per kilogram it undercuts the 250 g and 500 g packs and still costs more per gram than the 1 kg bucket. Two ratings are too thin for a top-pick or best-value badge. It fits a buyer who already wants a 5 kg tub and a printed 99.5% line, not someone choosing from review evidence.
Pros
Cons
Best for: You already want a 5 kg tub and a printed 99.5% minimum, and you can live with two ratings.
Less suitable: You are choosing on review evidence, or you need the lowest price per kilogram.
Specifications
Common questions
What assay does the listing state?
The title and a bullet say a minimum assay of 99.5% copper sulphate pentahydrate. The file has no certificate and no review text.
What container is included?
A resealable plastic tub. The unit count is 5,000 g. The shelf price in the file is £69.95.
What livestock and pool lines are printed?
A bullet names cattle footbaths and a pool warning about staining and a risk for swimmers. No MAPP number is printed. The wording is not an authorisation.
The title says a 5 L solution, but the bullets describe two dry pouches, 50 g of copper sulphate and 50 g of hydrated lime, and the unit count is 100 g, at £9.97. The hydrate of the copper pouch is not stated, and there is no assay, CLP block, or MAPP number. Packed in the Ribble Valley is a UK packing note, not an HSE authorisation. One UK review describes a garden treatment. The rating line is only 4.5 from two. You are buying measured dry ingredients, not five litres of ready mix, so do not divide £9.97 by five and call it a price per litre. It is the smaller lime kit if you are comparing these two pouch listings, and the wrong row if you wanted loose crystals by the kilogram.
Pros
Cons
Best for: You are comparing the two lime-kit listings and want the smaller pair of dry pouches, with the gram count in view.
Less suitable: You wanted five litres of liquid, loose pentahydrate crystals, or an authorised garden product.
Specifications
Common questions
Is this 5 litres of liquid?
The title says 5 L. The bullets say two dry pouches: 50 g copper sulphate and 50 g hydrated lime. The unit count is 100 g.
Is hydrated lime included?
Yes, as a separate sealed pouch. The hydrate of the copper sulphate pouch is not stated. No MAPP number and no CLP block are in the file.
What does the UK review say?
One review describes a garden treatment and says the lime pouch is there to hold copper on leaves. The rating line is 4.5 from 2. That is not an authorisation.
This 500 g pouch is bright blue pentahydrate at £7.97, with 4.4 from 159 amazon.co.uk ratings, the strongest star line among packs that have more than a hundred reviews. The listing names garden, paths, water features, and demonstrations, and it prints neither a numeric assay nor a CLP word. UK reviews describe plant scorch, including broad beans and a peach that lost its leaves, plus an insoluble residue. A question about aquatic life has no printed answer, and there is no MAPP number. Best Sellers Rank 42 in Copper is a catalogue position, not a clearance to treat water or a crop. It is the top pick here because the review sample is large and the hydrate is stated. Scorch reports mean a title that mentions plants is not an authorisation. On price per kilogram it loses to the 1 kg bucket at the same £7.97 shelf price.
Pros
Cons
Best for: You want the best-rated large sample of stated pentahydrate and can accept a higher price per kilogram than the 1 kg bucket.
Less suitable: You need the cheapest kilogram, a certificate of analysis, or an authorised plant, pond, or livestock product.
Specifications
Common questions
What is in the pack?
A 500 g pouch of copper sulphate crystals. The title says pentahydrate. There is no numeric assay and no MAPP number.
What do UK reviews say about plants?
Reviews mention plant scorch, including broad beans and a peach that lost its leaves, and also an insoluble residue. Those notes are buyer comments, not an authorisation.
Is an answer about aquatic life printed?
A listing question asks whether it is safe for aquatic life. This file does not print an answer. There is no CLP signal word.
The 250 g Minerals-water.ltd pack is pentahydrate at £5.97, with 4.3 from 188 amazon.co.uk ratings, the largest review count in this set. The title states pentahydrate and the bullets claim high purity without a numeric assay, so you cannot match a percentage to a certificate in this file. UK reviews mention dirt in the crystals and packs that arrived without instructions. There is no CLP signal word and no MAPP number. At about £23.88 per kilogram it costs about three times the 1 kg bucket on a per-gram basis. It is a small first buy when you want the hydrate on the label and a review sample you can actually read. Those purity complaints mean the adjective is not a lab result. The catalogue rank in Garden Fungicides does not authorise a crop treatment.
Pros
Cons
Best for: You want a small pentahydrate pack and a large amazon.co.uk review count before you commit to a kilogram.
Less suitable: You need the lowest price per kilogram, a printed assay, or an authorised plant-protection product.
Specifications
Common questions
Does the listing state pentahydrate?
Yes. The title and the bullets say pentahydrate. This file does not print a formula or a numeric assay.
Are instructions in the file?
The spec block has none. More than one UK review says the pack arrived without instructions.
Does the listing print a MAPP number or a CLP signal word?
Neither is in this file. The bullets say handle with care and use protective equipment, and store it cool and dry.
The 1 kg listing prints CuSO4·5H2O and the signal word Warning, at £7.97 with 4.3 from 113 ratings. That is the same shelf price as the 500 g pouch, so you get twice the mass. The brand line says MAIGORAY while the manufacturer says Minerals-water, and the pack is a bucket sold as a lab chemical, with gardening named in the title and the questions. One UK review reports a dark precipitate and extra water on a home weigh-in and calls the purity claim unsuitable for careful work, while other reviews call the price good value. Harmful if swallowed, plus skin and eye irritation, is printed, and no MAPP number is in the file. It is the best value crystal pack when you want a stated pentahydrate kilogram with a real review count. It is a poor stand-in for a certificate or an authorised product. The Fisher sheet for this pentahydrate uses Danger, which is stricter than Warning.
Pros
Cons
Best for: You want the most grams of stated pentahydrate per pound among packs with more than a hundred ratings.
Less suitable: You need one brand name throughout, a certificate, or an authorised pesticide or veterinary medicine.
Specifications
Common questions
Which brand and formula are printed?
The brand line says MAIGORAY. The manufacturer line says Minerals-water. The formula line is CuSO4·5H2O.
What hazard line is on the listing?
The signal word is Warning. The line says harmful if swallowed and causes skin and eye irritation. There is no MAPP number.
What does a UK review say about purity?
One review reports a dark precipitate and extra water on a home weigh-in and disputes the purity claim. Other reviews call the price good value.
XIXISUSU lists about 4 oz of pentahydrate at £19.51, with 3.8 from 22 amazon.co.uk ratings, the weakest star line in the set. The title says 99.9% and a bullet says more than 99%, while the formula bullet prints CuSO&C, which is not a usable formula. There is no gram line, so if you take 4 oz as about 113 g you are near £172 per kilogram. Written reviews in the file are marked United States and mention clumping and missing safety instructions, even though the rating count itself is the UK listing line. Gloves and goggles appear in the bullets, which is more protection language than most rows, but there is still no CLP word and no MAPP number. It is a poor gram-price buy beside the £7.97 crystal packs.
Pros
Cons
Best for: You specifically want a few ounces and will ignore the UK kilogram price of the larger crystal packs.
Less suitable: You want grams you can check, UK review text, or a price per kilogram near £8.
Specifications
Common questions
What purity figures are printed?
The title says 99.9%. A bullet says more than 99%. The formula bullet prints CuSO&C, which is left as printed and is not a usable formula.
What mass is stated?
4 oz on the title. There is no gram line in the spec block. The shelf price is £19.51.
Where are the written reviews from?
The rating line is amazon.co.uk, 3.8 from 22. The review texts in the file are marked United States. They mention clumping and missing safety instructions.
Angry Horse Forge lists 14 oz at £21.72, with an item weight of 396 g and a 99% assay claim, and there is no amazon.co.uk rating line in the file. The title says crystals while the spec says powder, and the hydrate is not stated. The container is a resealable plastic cylinder, and the manufacturer line is Earthworks Health LLC. A question about educational use has no printed answer, and there is no CLP block. At about £54.85 per kilogram, with no reviews, it is an expensive unresolved pack next to pentahydrate kilograms at £7.97 that carry more than a hundred ratings. It only makes sense if you specifically want this cylinder and accept that crystals versus powder is unsettled on the page. A missing rating line cannot take a badge.
Pros
Cons
Best for: You specifically want this resealable cylinder and you have already accepted the missing hydrate and the missing ratings.
Less suitable: You want stated pentahydrate, UK reviews, or a price near £8 per kilogram.
Specifications
Common questions
Is it crystals or powder?
The title says crystals. The spec says powder, and a bullet says powder granulation. The hydrate is not stated.
What assay and weight are printed?
A 99% assay is claimed. Item weight is 396 g. The title says 14 oz. The container is a resealable plastic cylinder. The shelf price is £21.72.
Is there a rating or a hazard block?
No customer-review line and no CLP block in this file. A listing question about educational use has no printed answer.
MI’s 100 g pack is sold as nila thotha at £22.59, with no rating line and with country of origin India. A bullet prints CuSO4, notes compounds with varying water of crystallisation, and does not state pentahydrate for this pack. The seller points to traditional products and says use under proper guidance, without a measured instruction, a named crop, or a hazard block. There is no MAPP number. At £22.59 it is cheaper than the other 100 g traditional-name listing and still about £226 per kilogram, far above the stated pentahydrate buckets. Guidance wording is not a UK authorisation to eat or apply the salt. Choose it only if that traditional name is what you searched for. Nothing in the file authorises food use.
Pros
Cons
Best for: You searched nila thotha and you will treat the guidance line as a reason to stop, not as instructions.
Less suitable: You need stated pentahydrate, a CLP word, reviews, or a low price per kilogram.
Specifications
Common questions
What formula is printed?
A bullet says CuSO4 and calls it cupric sulfate. It notes compounds with varying water of crystallisation. It does not state pentahydrate for this pack.
What guidance is printed?
The seller says traditional products and recommends use under proper guidance. There is no measured instruction, no named crop, and no hazard block.
What are the weight and price?
Item weight is 100 g. The shelf price is £22.59. There is no rating line and no MAPP number.
This 100 g pack is sold as neela thotha and tutia at £34.20, with country of origin India, manufacturer hyd, and no rating line. Hydrate is not stated, and fresh and pure is not a numeric assay. Food-style bullets, including non-GMO and allergen-style lines, are seller text. Cooking and skin questions in the file have no printed answer. There is no CLP block and no MAPP number. £34.20 for 100 g is about £342 per kilogram, an order of magnitude above the 1 kg pentahydrate bucket. Nothing in the listing authorises food use. It is a traditional-name pack for someone who already searched that name and accepts zero reviews, not a value crystal buy. If someone may have swallowed it, that is an NHS question, not a listing feature.
Pros
Cons
Best for: You searched the traditional name and you will not treat the food-style bullets as permission to cook with it.
Less suitable: You want pentahydrate, reviews, or anything like the £7.97 kilogram.
Specifications
Common questions
What is the pack?
100 g sold as neela thotha, tutia, and copper sulphate. The brand line is Generic. The manufacturer line is hyd. Country of origin is India. The shelf price is £34.20.
Does the listing state a hydrate or an assay?
No. A bullet says fresh and pure. There is no numeric assay and no rating line.
Are the food-style bullets an authorisation?
They are seller text, including non-GMO and allergen-style lines. Cooking and skin questions are in the file with no printed answer. There is no CLP block and no MAPP number.
We checked 38 copper sulfate listings and kept the 11 with a stored amazon.co.uk price in this file. This is not a laboratory test. The comparison score starts from the amazon.co.uk star rating times 20. A count of 30 or more keeps that figure. A count of 10 to 29 loses 12 points. A count under 10 loses 25. A title mass that disagrees with the item weight, or a litre title on a gram unit count, loses a further 6. A missing rating line stays at 0 and cannot take a badge. The figure on each product is that adjusted score divided by 10. The highest score is the top pick. Best value is a different listing: the lowest price per kilogram among stated pentahydrate crystal packs with at least 50 ratings.
Hydrate and formula
25%Whether the listing states pentahydrate or prints CuSO4·5H2O. A note about water of crystallisation is not the same as naming pentahydrate for that pack.
Review sample
25%Amazon.co.uk stars and the number of ratings. A count under 30 is reduced. A missing rating line scores 0. Written reviews marked United States are not treated as UK experience.
Price per kilogram
20%Shelf price against the stated mass. A litre title on a gram unit count is not priced as liquid. Best value uses stated pentahydrate packs with at least 50 ratings.
Hazard line
15%Whether the listing prints a CLP signal word. Warning on one pack is recorded as printed. A missing word is not treated as a milder hazard than the Fisher Danger class for the pentahydrate.
Authorisation on the listing
15%Whether a MAPP number is printed. None of these files has one. Garden, pond, footbath, and food-style wording stays seller text.
Buy the stated hydrate and the price per kilogram before the star average. Stars in this set are not a lab assay, and a title that names plants, a pond, or a footbath is not a MAPP number. None of the eleven listings prints one. If the job needs an authorised product, this shortlist does not supply it.
Copper sulfate in this comparison means the blue salt sold on amazon.co.uk as copper sulphate, almost always the pentahydrate, plus two kits that pair a copper sulphate pouch with hydrated lime. The pentahydrate is the form that includes water in the crystal. Listings that print CuSO4·5H2O are naming that form. Anhydrous copper sulphate is a different, paler salt, and it is not what these titles describe.
High purity, 99%, 99.5%, and 99.9% are seller lines here. Only the 5 kg listing prints a minimum of 99.5%, and it has two ratings and no review text. UK reviews on the large-sample packs mention dirt, a dark precipitate, or extra water. A formula is not a certificate of analysis.
The 5 L title is 100 g of dry pouches. The 10 L title has a unit count of 200 g. Dividing £9.97 or £14.97 by the litre figure invents a price per litre the pack does not contain. Read the unit count.
Garden, pond, footbath, and food-style lines are not a MAPP number and not a food authorisation. A review that describes plant damage is a reason to doubt the title, not a method to copy. If the salt may have been swallowed, contact NHS 111 or 999.
Start with the form printed on the listing, not the colour you hope to see. Pentahydrate, or the formula CuSO4·5H2O, is the blue crystal these large-sample packs name. The 500 g pouch, the 250 g pack, the 1 kg bucket, the conflicting 1.4 kg title, the 5 kg tub, and the 4 oz listing all state pentahydrate. The 1 kg and the 1.4 kg title also print the formula. The 14 oz listing says crystals in the title and powder in the spec, and it does not state a hydrate.
An assay is a number you can look for, not the adjective high purity. In this set the 5 kg bullets say a minimum of 99.5%, the 14 oz listing claims 99%, and the 4 oz title says 99.9% while a bullet says more than 99%. None of those files includes a certificate. The 4 oz formula bullet prints CuSO&C, which is not a formula you can check. The 250 g, 500 g, and 1 kg listings say high purity and print no percentage. UK reviews are the counterweight. On the 250 g pack, reviewers mention dirt.
Compare grams, not the first price on the card. The 1 kg bucket at £7.97 is the lowest price per kilogram among stated pentahydrate packs with at least 50 ratings, which is why it is best value. The 500 g pouch is the same £7.97 for half the mass. The 250 g pack is £5.97 and about £23.88 per kilogram, which can still be the right first buy if you want 188 ratings before a larger tub.
The hazard line is a buying fact, not a reason to improvise a use. Only the 1 kg listing prints a CLP signal word, and that word is Warning, with harm if swallowed and skin and eye irritation. The Fisher Scientific pentahydrate sheet uses Danger, serious eye damage, and a long-lasting hazard to aquatic life. Gloves and goggles on the 4 oz bullets are more protection language than a missing block, and they are still not a CLP word.
Three typical situations, each with a recommendation from this comparison.
You want stated pentahydrate and enough amazon.co.uk ratings to read scorch and residue comments before you buy. The 500 g pouch is the top pick at £7.97, with 4.4 from 159 ratings and a score of 8.8. It has no numeric assay and no MAPP number. It costs more per kilogram than the 1 kg bucket.
You want the lowest price per kilogram among stated pentahydrate packs with more than a hundred ratings. The 1 kg bucket is best value at £7.97, with CuSO4·5H2O and the signal word Warning, and 4.3 from 113 ratings. The brand line and the manufacturer line do not match. It is not a certificate and not an authorised product.
You want a short mass and the largest review count before you buy a kilogram. The 250 g pack is £5.97, pentahydrate, with 4.3 from 188 ratings. It is about £23.88 per kilogram. UK reviews mention dirt and packs that arrived without instructions. High purity on the bullets is not an assay.
The top pick is the 500 g copper sulphate pentahydrate pouch at £7.97. It scores 8.8, from 4.4 and 159 amazon.co.uk ratings, with pentahydrate in the title and no numeric assay. UK reviews mention plant scorch and residue, and there is no MAPP number. Best value is the 1 kg bucket, also £7.97, so you pay the same shelf price for twice the mass. It prints CuSO4·5H2O and Warning, with 4.3 from 113 ratings. The brand line says MAIGORAY and the manufacturer line says Minerals-water. Lime-kit titles that say 5 L or 10 L are dry pouches. Unrated 100 g packs are not a value buy.
1 kg copper sulphate pentahydrate
£7.97 for 1 kg of stated pentahydrate, the lowest price per kilogram among packs with at least 50 ratings.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources and the amazon.co.uk listings compared on this page. Listings stored 20 October 2026.
This page contains affiliate links. If you buy through them, we may earn a commission at no extra cost to you. Product links use the amazon.co.uk tag pcuk26-21. Prices, stars and review counts are the amazon.co.uk figures already stored for this set. This is not a laboratory test.
