---
title: "What Fernox products can I use to re-dose the system?"
description: "If the dip test shows less than 100ppm, installers can immediately resolve the issue by adding a high-quality inhibitor such as Fernox Protector F1 or where a filter is fitted, Protector+ Filter Fluid. The test can be re-taken once the inhibitor has circulated to confirm the level has been met."
url: https://help.fernox.app/en/articles/95-what-fernox-products-can-i-use-to-re-dose-the-system
collection: "Advice"
updated: 2026-10-05
language: en
alternates: [de, es, fr-be, fr, nl-be, nl, pl, ro, cs, sk, tr, sv]
---

# What Fernox products can I use to re-dose the system?

If the dip test shows less than 100ppm, installers can immediately resolve the issue by adding a high-quality inhibitor such as Fernox Protector F1 or where a filter is fitted, Protector+ Filter Fluid. The test can be re-taken once the inhibitor has circulated to confirm the level has been met.