Hydroponic fertiliser buying guide for your system

Updated: October 2026

You have a chilli in coir on a UK patio, or a small tank in the spare room, and amazon.co.uk has answered both with the same word.

You have a chilli in coir on a UK patio, or a small tank in the spare room, and amazon.co.uk has answered both with the same word. This hydroponic fertiliser buying guide is the fork before you buy: one mineral bottle, coco A and B, a recirculating bloom set, or a fish emulsion for soil and coco. It stops before a winner list and before a mixing procedure. Prices and the eight listings are on the hydroponic fertiliser comparison. The Products Compared editorial team wrote this on 21 October 2026 from those amazon.co.uk listings. It is not a laboratory trial. A qualifying purchase can earn a commission at no extra cost to you.

Our top picks

Badge	Product	Nutrient role	System named	Growth stage	Note	Price	Offer
Best overall	CANNA CANNA Coco A and B, 1 litre set	Two-part coco nutrient	Coco coir	Growing and flowering	9.4	about £17.56	View offer
Best value	Growth Technology Growth Technology Formulex, 1 litre	One-part mineral solution	Hydroponics, soil, foliar	Seedling to flower	9.2	about £11.77	View offer
Alternative	CANNA CANNA Aqua Flores A and B, 1 litre	Recirculating bloom nutrient	Recirculating systems	Flowering, not seedlings	7.8	about £23.01	View offer

Best overall

CANNA CANNA Coco A and B, 1 litre set

9.4/10about £17.56

View offer

Best value

Growth Technology Growth Technology Formulex, 1 litre

9.2/10about £11.77

View offer

Alternative

CANNA CANNA Aqua Flores A and B, 1 litre

7.8/10about £23.01

View offer

On this page

1.What you are actually buying
2.Match the bottle to the system
3.Read the listing before the stars
4.Price only after the match

What you are actually buying

A hydroponic fertiliser, in the sense the Royal Horticultural Society uses, is mineral salts you dissolve because the roots are not sitting in garden soil. That page gives a usual pH aim of 5.8–6.2, a conductivity check as plants drink, and a fresh mix about every two weeks. You are buying a base nutrient for one system, not a booster. A best-seller rank is a shelf position: on 20 October 2026 that node also listed products that are not nutrients. Formulex bullets say the mix is buffered, and they still do not print 5.8–6.2.

Match the bottle to the system

One bottle is enough for seedlings, a small kit, soil, or a foliar spray. Formulex is that listing: 1 litre at about £11.77 with a mixing ratio of 1:99, and 5 litres at about £29.89 whose dose field is not a usable figure. Skip it if the roots are in coir and you planned a two-part chart, or if the tank returns the solution and you are in flower. Coco A and B is the match for coir across growth and bloom. CANNA Coco is about £17.56. Aqua Flores at about £23.01 names recirculating systems and flowering, not seedlings. The all-watering-systems line on the Coco bullets is not permission to pour that set into an NFT tank. Fish-Mix at about £12.56 names soil, coco, and hydroponics, and the bullets stress outdoor vegetative growth. It is not a certified UK organic hydroponic fertiliser. The coco-versus-tank choice is on coco nutrients or recirculating hydroponic nutrients.

Testsieger

CANNA CANNA Coco A and B, 1 litre set

9.4/10about £17.56

View offer

Read the listing before the stars

Three cheap rows fail a readable-dose test. The generic bottle is about £5.56, a 50 ml title against a unit count of 1.0 millilitre, form refer to the description, ratio 1:50, and 4.0 from one review with no stored text. Qzdtue is about £9.09, a 110 ml title, the same 1 ml unit count, and one review at 1.0 that says the label is entirely in Chinese. Nouri is about £6.99 as 50 ml of A and B, with no star line, a granules field, and no mixing ratio. A high star line does not prove the formula. Fish-Mix is 4.7 from 2,059, with a weight of 227 g against a 1 litre title and a ratio of 1:0. CANNA Coco is 4.7 from 1,969, and the Amazon ratio 1:1 only says the parts are equal. If the label is not in English, or the unit count and the title disagree, stop.

Price only after the match

Entry is about £5.56 to £9.09. Mid is about £11.77 to £17.56: Formulex 1 litre, Fish-Mix, and CANNA Coco. Higher is Aqua Flores at about £23.01 and Formulex 5 litres at about £29.89, about £5.98 a litre if you finish it. Price per litre is the last check, and only between bottles that name your system and print a dose you can read in English. A cheaper coco set is the wrong saving for a recirculating bloom. Hydroponic Houseplant Focus is not one of these eight listings. Mixing order is on how to mix hydroponic nutrients.

Common questions

Is a hydroponic fertiliser just plant food dissolved in water?

Yes, in the narrow sense the Royal Horticultural Society uses: mineral salts in water, because the roots are not in garden soil. On this shelf the same word also covers coco A and B, a recirculating bloom set, and a fish emulsion. Dissolved plant food is the method, not one shared recipe.

When is one bottle enough, and when do you need A and B?

One bottle is enough for Formulex: seedlings, soil, foliar feeding, and general hydroponics. You need A and B for CANNA Coco in coir, or CANNA Aqua Flores in a recirculating tank in flower. The two CANNA sets are not interchangeable, and the concentrates must not be poured together.

Can the same bottle feed coco and a tank that recirculates?

Not on this shelf. CANNA Coco is the coco recipe for growth and bloom. It does not name NFT as its job. Aqua Flores names recirculating systems and flowering. Both saying hydroponic does not make them the same bottle.

Is BioBizz Fish-Mix the same kind of product as Formulex or CANNA Coco?

No. Fish-Mix is an organic fish emulsion. The highlight names soil, coco, and hydroponics, and the bullets stress outdoor vegetative growth. Formulex is one-part mineral. CANNA Coco is two-part for coir. No certificate number is stored, so this page does not call Fish-Mix a certified UK organic hydroponic fertiliser.

What should you check before you trust a 50 ml or 110 ml listing?

Check that the unit count, the liquid volume, and the title name the same amount, and that a dose is printed in English. The generic row is 50 ml against 1.0 millilitre, with no review text. Qzdtue is 110 ml against 1.0 millilitre, and the only review says the label is in Chinese. Nouri has no star line and a granules field.

Does a high star rating mean the formula matches your system?

No. Fish-Mix and CANNA Coco are both 4.7, from 2,059 and 1,969 reviews, and they are different jobs. Aqua Flores sits at 3.9 from 9 reviews. A high line means many people rated that listing. It does not match coir, a returning tank, and LECA at once.

Best hydroponic fertiliser