---
product_id: 4297502
title: "Flourish Phosphorus 500ml"
brand: "seachem"
price: "$48.09"
currency: USD
in_stock: true
reviews_count: 13
category: "Seachem"
url: https://www.desertcart.us/products/4297502-flourish-phosphorus-500ml
store_origin: US
region: United States of America
---

# Lasts up to 1.9 years dosing biweekly (20 gal) Optimized for lush planted aquarium growth 4500 mg/L potassium phosphate Flourish Phosphorus 500ml

**Brand:** seachem
**Price:** $48.09
**Availability:** ✅ In Stock

## Summary

> 🌿 Elevate your planted tank game with effortless phosphorus power!

## Quick Answers

- **What is this?** Flourish Phosphorus 500ml by seachem
- **How much does it cost?** $48.09 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/4297502-flourish-phosphorus-500ml)

## Best For

- seachem enthusiasts

## Why This Product

- Trusted seachem brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Long-Lasting Supply:** One 500ml bottle supports nearly 2 years of biweekly dosing
- • **Algae Defense Formula:** Helps prevent green spot algae (GSA) for crystal-clear tanks
- • **Synergistic Plant Care:** Pairs perfectly with Seachem’s N and K fertilizers for balanced growth
- • **User-Friendly Application:** Pre-mixed liquid formula removes guesswork from phosphate dosing
- • **Precision Phosphorus Boost:** Easily dose 2.5ml per 20 gallons for consistent plant nutrition

## Overview

Seachem Flourish Phosphorus 500ml is a safe, concentrated potassium phosphate supplement designed to optimize phosphorus levels in planted aquariums. With a potent 4500 mg/L solution, it simplifies dosing to promote vigorous plant growth while preventing green spot algae. Ideal for hobbyists seeking a long-lasting, easy-to-use liquid fertilizer that integrates seamlessly with nitrogen and potassium supplements for a thriving aquatic ecosystem.

## Description

Seachem Flourish Phosphorus 500ml

Review: Phosphorus per day keeps the GSA away - Great stuff but a bit watered down. They suggest dosing 2.5ml (half cap) for each 20 gallons once or twice a week. So if you dose it twice a week into a 20 gallon this 500ml bottle would last you about 1.9 years This is for planted tanks or simply to remove GSA (green spot algae). you can also add some nerite snails. they eat that GSA up. This product makes it very easy to administer your fertilizers, and with a small planted tank it will last you a while. If you have a larger tank I would suggest going with dry fertilizers. You can dose EI (estimated index) where you just scoop a certain measurement of each dry fert in per day. This process is basically over fertilizing so you know you reach your levels and making sure to do your weekly water changes so everything can reset and you dont have buildup of certain fertilizers. But as for this product. It is basically a dry fert mixed with water to make it easy on you. You would usually use this in conjunction with Nitrogen and Potassium which seachem sells all 3 in a starter pack the "plant pack enhancer npk level 2" but phosphorus itself is one of the macro nutrients that plants need. If you notice your plants are not growing and you have algae growing. its probably time to start dosing fertilizer and this particular macro nutrient will help your plants grow.
Review: Amazing Growth! - This stuff is easy to use I love it. I noticed a significant improvement in in my plant growth when I started dosing Seachem Phosphorus. My 80 G heavily stocked aquarium gets plenty of Nitrates from fish food. So I dont dose Nitrogen. My Phosphates were at 1ppm and nitrates at 15-30 before I started dosing Phosphates. My fish food is low in phosphates... I feed New Life Spectrum small sinking pellets. I only need to dose Seachem Advance, Phosphorus, Iron, Potassium and that's all. I use the Seachem root tabs for the Jungle Val and desertcart Sword fern. I do use a small amount of Equilibrium due low GH in my Tap water. 30% water changes at least weekly. After adding Phosphorus my Nitrates 15-30, phosphates 7ppm. Gh 6-7 and KH 3-4. Plants doing well in a all sand substrate. Growth is amazing.

## Features

- Phosphorus supplement for the Planted Aquarium
- A safe 4500 mg/L solution of potassium phosphate
- Takes the guesswork out of phosphate dosing

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0002APIJQ |
| ASIN  | B0002APIJQ |
| Age Range Description | All Life Stages |
| Best Sellers Rank | #34,611 in Pet Supplies ( See Top 100 in Pet Supplies ) #354 in Aquarium Water Treatments |
| Brand Name | Seachem |
| Color | clear |
| Customer Reviews | 4.8 4.8 out of 5 stars (791) |
| Date First Available | October 2, 2001 |
| Date First Available  | October 2, 2001 |
| Department | Unisex-Adult |
| Department  | Unisex-Adult |
| Directions | Used for aquarium |
| Included Components | Seachem Flourish Phosphorus 500ml |
| Is Discontinued By Manufacturer  | No |
| Item Dimensions LxWxH | 7.6 x 2.2 x 1.4 inches |
| Item Package Dimensions L x W x H | 7.48 x 2.44 x 2.44 inches |
| Item Weight | 1.15 Pounds |
| Item model number | 193 |
| Item model number  | 193 |
| Manufacturer | Seachem Laboratories, Inc. |
| Manufacturer  | Seachem Laboratories, Inc. |
| Material | Plastic |
| Model Name | Seachem Flourish Phosphorus 500ml |
| Number of Items | 1 |
| Product Dimensions  | 7.6 x 2.2 x 1.4 inches; 1.15 Pounds |
| Size | 100 mL, 250 mL, 500 mL, 2 L, 4 L |
| Specific Uses for Product | Active |
| Target Audience Keyword | Fish |
| Warranty Description | Warranty |

## Product Details

- **Brand:** Seachem
- **Item Form:** Liquid
- **Item Weight:** 1.15 Pounds
- **Liquid Volume:** 500 Milliliters
- **Manufacturer:** Seachem Laboratories, Inc.

## Images

![Flourish Phosphorus 500ml - Image 1](https://m.media-amazon.com/images/I/517Gt4xFYSS.jpg)

## Questions & Answers

**Q: My tap water already has phosphate in it. Is there any need for this also?**
A: Yeah ,I guess so. If you have enough  phosphate, your plants are growing & there are no algae blooms that should be good, I try to keep my levels at 1.0 mg/l. This product is also nitrite free ,I think it's wise to take something like that into consideration. I hope this helps you out.

**Q: Can you please advise how much you dose per week in your planted tank?**
A: No, this is for freshwater plants.

**Q: Can this be used house plants?**
A: It can but it will need to be diluted as it's in a concentrated form. I'd try 1ml per gallon and see the result. If the plant tips appear to be burnt, I'd do half a ml. If it seems fine, try increasing to 1.5ml/g. Hope this helps.

**Q: Can this product be used in a saltwater tank for the plants**
A: Yes it can however brightwell makes a macro nutrient designed just for reef plants like chaeto, algae, and sea grass.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Phosphorus per day keeps the GSA away
*by R***G on June 1, 2016*

Great stuff but a bit watered down. They suggest dosing 2.5ml (half cap) for each 20 gallons once or twice a week. So if you dose it twice a week into a 20 gallon this 500ml bottle would last you about 1.9 years This is for planted tanks or simply to remove GSA (green spot algae). you can also add some nerite snails. they eat that GSA up. This product makes it very easy to administer your fertilizers, and with a small planted tank it will last you a while. If you have a larger tank I would suggest going with dry fertilizers. You can dose EI (estimated index) where you just scoop a certain measurement of each dry fert in per day. This process is basically over fertilizing so you know you reach your levels and making sure to do your weekly water changes so everything can reset and you dont have buildup of certain fertilizers. But as for this product. It is basically a dry fert mixed with water to make it easy on you. You would usually use this in conjunction with Nitrogen and Potassium which seachem sells all 3 in a starter pack the "plant pack enhancer npk level 2" but phosphorus itself is one of the macro nutrients that plants need. If you notice your plants are not growing and you have algae growing. its probably time to start dosing fertilizer and this particular macro nutrient will help your plants grow.

### ⭐⭐⭐⭐⭐ Amazing Growth!
*by E***D on August 7, 2019*

This stuff is easy to use I love it. I noticed a significant improvement in in my plant growth when I started dosing Seachem Phosphorus. My 80 G heavily stocked aquarium gets plenty of Nitrates from fish food. So I dont dose Nitrogen. My Phosphates were at 1ppm and nitrates at 15-30 before I started dosing Phosphates. My fish food is low in phosphates... I feed New Life Spectrum small sinking pellets. I only need to dose Seachem Advance, Phosphorus, Iron, Potassium and that's all. I use the Seachem root tabs for the Jungle Val and Amazon Sword fern. I do use a small amount of Equilibrium due low GH in my Tap water. 30% water changes at least weekly. After adding Phosphorus my Nitrates 15-30, phosphates 7ppm. Gh 6-7 and KH 3-4. Plants doing well in a all sand substrate. Growth is amazing.

### ⭐⭐⭐⭐⭐ seachem is the best, fool proof.
*by C***S on August 9, 2014*

I only use seachem products. I dont want to take a risk with diy ferts, or mixes people sell on forums. I don't trust anything that hasn't been researched and tested. I use all of the seachem plant fert line and my plants are always healthy and growing fast. Crypts love the line up, they spread like crazy when using the entire line of ferts. They make it nearly impossible to screw up dosing tanks. I use them in my 6 tanks ranging from 4 gallons to 30 gallons.

## Frequently Bought Together

- Seachem Flourish Phosphorus 500ml
- Seachem Flourish Potassium 500ml
- Seachem Flourish Nitrogen 500ml

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*Product available on Desertcart United States of America*
*Store origin: US*
*Last updated: 2026-02-20*