---
title: "Reducing false visual alerts — Lemwatch Help"
description: "Cut noisy visual alerts from ads, timestamps, and personalised content without missing real changes."
canonical: "https://lemwatch.com/help/reducing-visual-noise"
source: "https://lemwatch.com"
---

# Reducing false visual alerts

> Cut noisy visual alerts from ads, timestamps, and personalised content without missing real changes.

## Quick answer

 Combine three tools: mask ads with [ignore zones](https://lemwatch.com/help/ignore-zones), raise the [sensitivity threshold](https://lemwatch.com/help/visual-diff-thresholds) to 10–15%, and scope to a [CSS selector](https://lemwatch.com/help/css-selector-monitoring) when the whole page is noisy.

## What causes visual noise

- Ad networks and personalised content

- Timestamps and "X minutes ago" strings

- A/B tests randomly showing variants

- Cookie banners that appear on some geos

- Live chat widgets that unread-count

## Where to fix it

 **Visual Monitoring → [page]** — every knob is on the page settings screen.

## How to fix it

- Look at the last 3 diffs — identify which region changed each time.

- If it's always the same region → add an ignore zone .

- If noise is spread across the page → raise sensitivity to 10–15%.

- If only one section matters → switch to CSS selector monitoring .

- For rotating text-only noise → enable rotating content scrub .

## FAQ

### How do I know if a mask is too big?

 Approved changes will drop to zero. Shrink the mask until real changes come through again.

### Can Lemwatch auto-detect ads?

 Not yet. Auto-mask for common ad networks is on the roadmap.

## Related

- Ignore zones

- Visual diff thresholds

- Rotating content noise


## Related

- [Help centre](https://lemwatch.com/help)
- [Ignore zones for visual monitoring](https://lemwatch.com/help/ignore-zones)
- [Visual diff thresholds explained](https://lemwatch.com/help/visual-diff-thresholds)
- [Rotating content noise (visual + text diff)](https://lemwatch.com/help/rotating-content-noise)
- [Monitor a single element with CSS selectors](https://lemwatch.com/help/css-selector-monitoring)
- [Why am I getting false alerts?](https://lemwatch.com/help/why-am-i-getting-false-alerts)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [How do referral credits work?](https://lemwatch.com/help/referral-credits-and-rewards)