# LSI Pool and Spa Calculator vs Blue Def Decoder

The clearest difference is price: LSI Pool and Spa Calculator at Free against Blue Def Decoder's $3.99. LSI Pool and Spa Calculator also leads on rating (5.0 vs 3.0) and update cadence (every 5 weeks vs every 5 months). Blue Def Decoder's advantage is in-app purchases (none vs 2) and ratings volume (6 vs 1). On ads and device support there is nothing between them.

LSI Pool and Spa Calculator is free to download; Blue Def Decoder costs $3.99 up front. LSI Pool and Spa Calculator sells 2 in-app purchases, starting at $1.99 per month. Blue Def Decoder asks for nothing beyond the download.

LSI Pool and Spa Calculator holds the better App Store score, 5.0 against 3.0. That said, the two scores are not equally well evidenced: Blue Def Decoder has 6 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 79% of LSI Pool and Spa Calculator's written reviews are positive against 60% of Blue Def Decoder's.

LSI Pool and Spa Calculator ships an update every 5 weeks, Blue Def Decoder every 5 months. The most recent releases landed on November 10, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | LSI Pool and Spa Calculator | Blue Def Decoder |
| --- | --- | --- |
| Price | **Free** | $3.99 |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/lsi-pool-and-spa-calculator/id373769371/reviews)** | [3.0 (6 ratings)](https://appshunter.io/ios/app/blue-def-decoder/id6751862301/reviews) |
| Number of ratings | 1 | **6** |
| Positive reviews | **78.6% of reviews** | 60.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 5 weeks** | Every 5 months |
| Monetization | **Free with in-app purchases** | Paid |
| Size | 8 MB | 20 MB |
| Requires iOS | 17.6 | **15.1** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Verosocial Studio](https://appshunter.io/developer/354566841) | [Mako Technology Labs](https://appshunter.io/developer/1832176903) |

## What reviewers say

### LSI Pool and Spa Calculator

[App page](https://appshunter.io/ios/app/lsi-pool-and-spa-calculator/id373769371)

This app helps pool and spa professionals organize water testing readings, customer details, and service visits. It calculates the Langelier Saturation Index, tracks historical data, and generates service reports for clients.

**Highlights:** Calculate LSI from water parameters, Track customer and site details, Log service visits and chemical actions, View historical data and charts, Generate service reports, Schedule future visits

**Features:** macOS Compatibility, Family Sharing, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| LSI Calculators pro Monthly | $1.99 | per month |
| LSI Calculators pro lifetime | $14.99 | one-time |


### Blue Def Decoder

[App page](https://appshunter.io/ios/app/blue-def-decoder/id6751862301)

Instantly determine the freshness of your Diesel Exhaust Fluid (DEF) by entering the code from your container. This app helps you confirm DEF hasn't expired, track shelf life, and verify vehicle compliance, removing guesswork for diesel vehicle owners.

**Highlights:** Check DEF freshness, Enter 5-11 character codes, View manufacturing date, See freshness status, Track shelf life, Verify vehicle compliance

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is LSI Pool and Spa Calculator free?

LSI Pool and Spa Calculator is free to download, with in-app purchases available.

### Is Blue Def Decoder free?

Blue Def Decoder costs $3.99, with no in-app purchases.

### Which has better reviews, LSI Pool and Spa Calculator or Blue Def Decoder?

LSI Pool and Spa Calculator is rated higher. LSI Pool and Spa Calculator averages 5.0 out of 5 from 1 ratings, while Blue Def Decoder averages 3.0 from 6 ratings.

### Do LSI Pool and Spa Calculator or Blue Def Decoder have ads?

Neither LSI Pool and Spa Calculator nor Blue Def Decoder shows ads.

### Which is updated more often, LSI Pool and Spa Calculator or Blue Def Decoder?

LSI Pool and Spa Calculator ships an update every 5 weeks, and Blue Def Decoder every 5 months. Most recently, LSI Pool and Spa Calculator was updated on November 10, 2026 and Blue Def Decoder on October 30, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*