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How to dose aquarium fertiliser

Updated: October 2026

The tank is a known number of litres, and the label uses a rate that belongs to that product alone. How to dose aquarium fertiliser turns those rates into a weekly or daily amount and says when to use less. The [aquatic plant fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/aquatic-plant-fertiliser) is where the bottles are listed. The Products Compared editorial team took the doses from the amazon.co.uk listings stored on 19 October 2026, and from the maker's page where the amazon bullets are silent. The figures below are arithmetic from those rates, not a trial in your water. If you buy through our links, we may earn a commission at no extra cost to you. Which type to buy is the [buying guide](/hub/fertiliser-soil-and-bark-mulch/aquatic-plant-fertiliser/sub/aquatic-plant-fertiliser-buying-guide).

The tank is a known number of litres, and the label uses a rate that belongs to that product alone. How to dose aquarium fertiliser turns those rates into a weekly or daily amount and says when to use less.

Our top picks

Easy Life Easy-Life ProFito 500 ml

Best overall

Easy Life Easy-Life ProFito 500 ml
8.6/10about £9.49
View offer
AquaDesign AquaDesign CARBO 2,500 ml

Alternative

AquaDesign AquaDesign CARBO 2,500 ml
7.0/10about £19.99
View offer
AquaDesign AquaDesign PLANT+ 500 ml

Alternative

AquaDesign AquaDesign PLANT+ 500 ml
7.3/10about £10.99
View offer
On this page
  1. 1.Dose the bottle you bought
  2. 2.Water changes and splitting the week
  3. 3.When the pump and the label disagree
  4. 4.When to add less

Dose the bottle you bought

ProFito is 10 ml per 100 litres weekly, and Easy-Life also allows about one seventh each day. The amazon bullets leave out the word week. PLANT+ is 10 ml per 30 litres a week. PLANT LITE is 10 ml per 50 litres a week, and the 500 ml listing also prints 1 pump per 6 litres a week. Flourish's amazon bullets do not state a dose. Seachem's note is 5 ml per 250 litres, once or twice a week. CARBO is 1 ml per 50 litres a day, maximum 2 ml. For a 100 litre tank, as sums from the label: PLANT+ is about 33 ml a week, PLANT LITE 20 ml, ProFito 10 ml at the full rate or nearer 3 ml if you start around one third. Flourish is about 2 ml once or twice a week, from the manufacturer rate missing on the amazon page. CARBO is 2 ml a day, or 4 ml at the listed maximum. If the bottle is carbon, use the daily cap.

Water changes and splitting the week

Add the nutrient dose after the water change, into the water that is staying, so you are not feeding a bucket you are about to throw away. Where algae is already high, a large water change comes first, then a smaller dose. Easy-Life lets you split the ProFito week into smaller daily amounts that still add up to the week. One reviewer on the 1,000 ml listing describes 10 ml a day in a 100 litre tank with CO2. That is about seven times the maker's weekly 10 ml per 100 litres, and it is a reviewer's method, not the label. If the nitrate test is the open question, the complete versus lite page is the fork.
Easy Life Easy-Life ProFito 500 ml

Testsieger

Easy Life Easy-Life ProFito 500 ml
8.6/10about £9.49
View offer

When the pump and the label disagree

The 1,000 ml PLANT+ listing states 10 ml per 30 litres a week and says a 3 ml pipette is included. Reviewers of that listing also describe a pump marked 1 pump per 4 litres. Those two instructions cannot both be the weekly total unless you have measured what one pump delivers. The listing does not print that pump volume. Use the millilitre line. Draw 10 ml per 30 litres with the pipette and ignore a pump count you have not checked. PLANT LITE 500 ml has the same kind of pair: 10 ml per 50 litres a week, and 1 pump per 6 litres a week. Until you know the pump's millilitres, the 10 ml figure is the one you can audit. A dose that feels weak is a reason to watch new leaves for two or three weeks before you multiply the label because a review did.

When to add less

Easy-Life's ProFito page says to start low, raise the dose if young leaves are pale, and cut back if algae appears or if extra fertiliser stops improving growth. If the glass greens up after the PLANT+ rate of 10 ml per 30 litres, drop towards half and change more water. CARBO does not follow that weekly cut. Its maximum is 2 ml per 50 litres a day, so a 100 litre tank stops at 4 ml a day. Going past that because the plants pearled is the overdose Practical Fishkeeping warns about for liquid carbon as a class. If livestock die within hours of a dose, stop and do a large water change. One ProFito reviewer reported corydoras losses after dosing. One report is not a cause, and it is still a reason to pause.

Common questions

Do I dose every day or once a week?
PLANT+ and PLANT LITE are written as weekly doses. ProFito is weekly at Easy-Life, with the option of about one seventh each day. CARBO is daily, with a maximum. Flourish is once or twice a week on Seachem's note, which the amazon bullets do not print. A daily habit copied from CARBO onto PLANT+ would stack a week of fertiliser in one day.
Do I add fertiliser before or after a water change?
Add it after the change, to the water that is staying in the tank. Dosing before you drain throws part of the bottle away. If algae is already high, a large water change comes first, then a reduced dose, which is the pattern Aquarium Gardens and Tropica describe for their own products.
How much ProFito for 100 litres?
The full rate is 10 ml per 100 litres a week. Easy-Life also says to begin near one third, so a first week can be about 3 ml, split across days if you prefer. The amazon bullets state 10 ml per 100 litres and do not print per week. Raise the dose only if young leaves stay pale, and cut it if algae increases.
How much PLANT+ for 60 litres?
Ten millilitres per 30 litres a week is 20 ml a week for 60 litres. The included pipette is 3 ml, so that week is a little under seven pipettes if you dose it all at once after the water change. The 1,000 ml pump mark of 1 pump per 4 litres is a different instruction. Measure the 20 ml.
Can I use the CARBO daily figure on a nutrient bottle?
CARBO's 1 ml per 50 litres is a daily carbon rate, and 2 ml per 50 litres is the listed maximum. ProFito, PLANT+, PLANT LITE, and Flourish use their own weekly rates. Putting the carbon figure on a nutrient bottle, or the nutrient figure on CARBO every day, mixes two schedules. Keep the daily cap on the carbon bottle and the weekly line on the feed.

Related pages

Liquid carbon aquarium fertiliser

Aquatic plant fertiliser

Best aquarium plant fertiliser for your tank setup

Aquarium plant fertiliser buying guide: pick a type

Complete vs lite aquarium fertiliser for your tank

Sources

Public UK and maker sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the nine amazon.co.uk listings captured on 19 October 2026. A shrimp-safe bullet is a listing claim. Flourish's copper figure is the maker's statement, not an independent UK lab test. CARBO's algae line is not confirmed here as an HSE authorisation.

  1. Practical Fishkeeping, growing aquarium plants (retrieved 19 October 2026)
  2. Practical Fishkeeping, gas versus liquid carbon (retrieved 19 October 2026)
  3. Seachem Flourish (retrieved 19 October 2026)
  4. Seachem Flourish dosing instructions (retrieved 19 October 2026)
  5. Easy-Life ProFito (retrieved 19 October 2026)
  6. GOV.UK, manufacturing and marketing fertilisers (retrieved 19 October 2026)
  7. GOV.UK, product labelling (retrieved 19 October 2026)
  8. HSE, regulated biocides (retrieved 19 October 2026)