Comparison

LSI Pool and Spa Calculator vs Blue Def Decoder

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

LSI Pool and Spa Calculator

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
Read full description

You put care into every pool and spa you look after. Thank you for using LSI Pool and Spa Calculator. Your attention to water testing matters, and this app helps you keep readings, customer details, and service visits organized. Whether you maintain your own spa or look after several properties, bring your water balance calculator and service log together. Enter measured values, check the Langelier Saturation Index, and keep a useful record for your next visit. CHECK POOL AND SPA WATER BALANCE - Calculate LSI from measured pH, water temperature, calcium hardness, total alkalinity, and total dissolved solids. - See the calculated saturation pH and a result category. - Review whether readings suggest a scale or corrosion tendency. - Work in Fahrenheit or Celsius and convert the entered temperature when switching units. - Find the formula, measurements, and result ranges in Help. KEEP READINGS YOU CAN FIND AGAIN - Save measurements under reusable pool, spa, and property names. - Record dates and notes about water condition, treatments, or follow-up work. - Search saved history by site, result category, or notes. - Sort readings, correct saved inputs, and recalculate after an edit. - Duplicate a record for another visit. - Review a reading beside the records list on wider iPad layouts. PLAN AND RECORD SERVICE VISITS - Schedule visits for a saved pool or spa site. - Add a technician, visit status, and completed-work checklist. - Record actual chemical actions, service observations, and customer notes. - Link a saved water reading or enter fresh measurements for the visit. - Preview a service report before saving. - Keep an unfinished new visit as a local draft. - Note the next service or retest date and book a separate visit when ready. KEEP CUSTOMERS AND SITES CONNECTED - Save customer names, companies, phone numbers, emails, addresses, and notes. - Add customers manually or choose contacts to copy from Apple Contacts. - Link several sites to one customer and give each site its own address. - Keep local contact edits separate from device Contacts. - Find mapped sites using their address or a linked customer's address. - Search the site list even when a property still needs an address. REVIEW CHANGES OVER TIME - Explore charts for LSI, pH, temperature, hardness, alkalinity, and TDS. - Compare minimum, maximum, and average measurements. - Review history by customer or individual site. - Filter readings by result category. - Use Quick Calc for a check outside saved site history. - Set a weekly testing goal and review milestones in Habits & Progress. USE INPUT TOOLS THAT FIT THE JOB - Reset a form or search from its three-line menu. - Share current field labels and values, including an unfinished form. - Expand Details when you need guidance and keep notes in their fields. - Enable Sample Data or Randomize in Settings when you want practice inputs. Both start off. - Choose Light, Dark, or system appearance. TAKE YOUR RECORDS WITH YOU - Export readings, sites, contacts, or service visits as CSV or PDF. - Save JSON backups and review processing limits before relying on a backup. - Use Apple Watch for independent LSI calculations, local saved readings, and sharing. Watch readings do not sync with iPhone. The free iPhone app supports up to five saved readings. LSI Pro adds a larger reading allowance, spreadsheet review, backup import, and individual text and PDF reports. Watch calculation, saving, and sharing are free. Use reliable water tests alongside equipment and treatment guidance. LSI describes saturation tendency; it does not calculate chemical doses. Keep testing, keep good notes, and head into your next visit prepared. Monthly Pro is a 1-month auto-renewable subscription. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

Blue Def Decoder

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
Read full description

Easily check the freshness of your Diesel Exhaust Fluid (DEF) with Blue Def Decoder. Enter the 5–11 character code printed on your DEF container — whether it’s the short date section or the full code — and instantly see the manufacturing date and freshness status. Use Blue Def Decoder to: Confirm your DEF hasn’t expired Track shelf life for storage Verify compliance for your vehicle Blue Def Decoder saves you time and removes the guesswork from DEF code verification. Perfect for Sprinter van owners, diesel truck drivers, and anyone who needs quick, accurate results.

Screenshots

LSI Pool and Spa Calculator4 screens
Blue Def Decoder4 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard8 real differences · 2 level
LSI Pool and Spa Calculator versus Blue Def Decoder: the parameters behind the verdict, then further details
ParameterLSI Pool and Spa CalculatorBlue Def Decoder
PriceFree — better$3.99
Rating5.0 (1 ratings) — better3.0 (6 ratings)
Positive reviews78.6% of reviews — better60.0% of reviews
Number of ratings16 — better
Update frequencyEvery 5 weeks — betterEvery 5 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
DevicesiPhone, iPadiPhone, iPod
Requires iOS17.615.1 — better
Further details — not scored
Size8 MB20 MB
Age rating4+4+
DeveloperVerosocial StudioMako Technology Labs

Customer experience

LSI Pool and Spa Calculator

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews14 reviews
Positive78.6%
Neutral7.1%
Negative14.3%

Blue Def Decoder

All ratings6 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews5 reviews
Positive60.0%
Neutral0.0%
Negative40.0%

In-app purchases

2 purchases

LSI Pool and Spa Calculator

Subscriptions1
  • LSI Calculators pro Monthly$1.991 Month
One-time1
  • LSI Calculators pro lifetime$14.99
None

Blue Def Decoder

No in-app purchases

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.

Other comparisons