Seachem Flourish Review
A long-standing comprehensive supplement rich in iron, trace elements and micros. Excellent alongside a nitrogen source in low-tech tanks, though on its own it is light on macros.
By the AquaVerdict Editorial Team · How we research & review
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Pros
- Rich, comprehensive blend of iron, trace elements and micros
- Gentle and forgiving — very hard to overdose at label rates
- Cheap and widely stocked; a bottle lasts a long time
- Ideal micro partner in a low-tech tank with a fish-fed nitrogen supply
Cons
- Light on macros — it is not a true all-in-one on its own
- Heavier-planted tanks may need a separate nitrogen/potassium source
What Flourish actually is
Seachem Flourish has been on shop shelves for decades, and it earns its place as a comprehensive trace and micronutrient supplement. It is rich in iron and the full spread of trace elements plants need in small amounts, and it is gentle enough that overdosing at the label rate is very hard to do. What it is not is a heavy macro fertiliser — it carries little nitrogen, phosphorus or potassium by design.
Getting the pairing right
That design makes it excellent in a specific situation: a low-tech tank with a reasonable fish load, where waste already supplies much of the nitrogen and phosphorus and you just need to top up the micros. Add a heavier plant load or bright light and CO2, and plants will start to want macros that Flourish does not provide — at which point you either add a separate nitrogen/potassium source or switch to a true all-in-one. Think of Flourish as one half of a complete feeding routine, and it makes sense.
How it fits with our other picks
If you would rather not juggle components, an all-in-one like Aquarium Co-Op Easy Green does macros and micros in a single bottle. For a targeted iron boost on red plants, see Seachem Flourish Iron. Compare the full range on our plant fertilizers hub, and match your setup to the right lighting.
A proven, gentle micronutrient supplement that shines in low-tech tanks. Just remember it is the trace half of feeding — pair it with a nitrogen source or an all-in-one for the full job.
Where this one sits in its aisle
At 13 $, it is the 6 cheapest of the 10 models in this category published here.
- Cheapest in the aisle8 $
- Median13 $
- Dearest in the aisle37 $
Seachem Flourish — frequently asked questions
Is Seachem Flourish an all-in-one fertiliser?
Not quite. Flourish is a comprehensive supplement that is strong on iron, trace elements and micronutrients but deliberately light on the macros (nitrogen, phosphorus, potassium). In a lightly-stocked low-tech tank, fish waste often supplies enough nitrogen and phosphorus, so Flourish tops up the rest nicely. In a heavily-planted or high-light tank you will usually want to add a macro source — or use a true all-in-one instead.
How does it compare to an all-in-one liquid?
An all-in-one such as Easy Green or APT Complete bundles macros and micros in one bottle, so it is simpler for most people. Flourish is the micro half of the equation — a great, gentle supplement, but you pair it with a nitrogen/potassium source (or rely on fish load) to complete the picture. If you want one bottle and no thinking, choose an all-in-one; if you like to dose components, Flourish is a classic.
Can I overdose Flourish?
It is very forgiving at the label dose of about 5 mL per 250 L a couple of times a week. Because it is micro-focused and dilute, accidental over-dosing is far less risky than with concentrated liquid-carbon or macro products. Still, start at the recommended rate and increase only if plants show trace deficiencies.
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Our score
8.4/ 10
A proven, gentle micronutrient supplement that shines in low-tech tanks. Just remember it is the trace half of feeding — pair it with a nitrogen source or an all-in-one for the full job.
Who this one is for
A low-tech planted tank owner who wants a proven micronutrient and trace-element supplement, dosed twice a week.
Compared with its closest rivals
Same category, nearest prices. Only the specifications every one of them states are shown — a half-empty column compares nothing.
| Model | Price | Type | Dosing | Contains | Best for |
|---|---|---|---|---|---|
| Seachem Flourish | 13 $ | Comprehensive trace/micro supplement | 5 mL per 250 L, 1–2× per week | Micro-focused (Fe + traces); minimal macros | Low-tech tanks; micro top-up alongside macros |
| Seachem Flourish Iron | 13 $ | Single-nutrient iron supplement | 5 mL per 200 L, 1–2× per week as needed | Iron (ferrous gluconate); no macros | Red and iron-hungry plants under good light |
| Seachem Flourish Tabs | 13 $ | Substrate root tablets (40 caps) | 1 tab per 10–15 cm of substrate, every 3–4 months | Micro-focused (Fe + traces), slow-release at roots | Heavy root-feeders in inert gravel or sand |
| Seachem Flourish Potassium | 12 $ | Single-element supplement (potassium) | 5 mL per 30 US gal raises K by ≈ 2 mg/L | Potassium (from potassium sulfate) only | Correcting potassium deficiency; component dosers |
What separates these models
- If price decides: Seachem Flourish Potassium, at 12 $.
- Highest Dosing in the table: Seachem Flourish Potassium (5 mL per 30 US gal raises K by ≈ 2 mg/L).
If this one is not the right fit
- On a tighter budget: API Leaf Zone, at 8 $ in the same category. see the review
Guides that feature it
Price and availability
A reference exists on these Amazon stores: Germany, United Kingdom, United States. Listed is not the same as in stock — availability changes daily.
Details checked on July 15, 2026.
Sources
Specifications: manufacturer sheet and Amazon product page. Prices and availability: Keepa. No product on this site has been physically tested.
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