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Pool and Hot Tub Test Log

Save each water test on your phone, and the latest one becomes a plan: what to add, how much and in what order. Over a few weeks the log shows what keeps drifting, which a single test never can.

Opening your log…

Save each water test on your phone, and the latest one becomes a plan: what to add, how much and in what order. Over a few weeks the log shows what keeps drifting, which a single test never can.

How the log works

  • The pool plan is the pool chemistry calculator’s own, so a dose here matches a dose there. Leave blank anything you didn’t test: nothing is worked out from a number you didn’t give.
  • The hot tub plan uses your tub maker’s ranges, in the order Bullfrog’s manuals give and the Pool & Hot Tub Alliance agrees with: alkalinity first, then pH, then calcium, then sanitizer. Its doses are worked out from the same figures as the pool’s, scaled to a few hundred gallons, with dry acid where the pool plan uses muriatic, because the spa makers name it and Bullfrog says never to use muriatic acid in its tubs.
  • Every plan is for the test you just took. Add the first product, let it circulate, and test again before the next one. Then log that test too.
  • Your log stays on this device. Read the privacy page for everything the site keeps in your browser.

Hot tub ranges, maker by maker

The makers don’t agree, and every owner’s manual says to follow its own figures. These are the ranges the log uses, in ppm, from each maker’s current manual. The hot tub chemistry guide explains what each one does.

WhoAlkalinityCalciumSanitizer
Hot Spring and Caldera40 to 120, ideal 8075 to 150, or 25 to 75 with their salt systemChlorine 1 to 5
Jacuzzi, with FROG @ease100 to 150150 to 250Chlorine 0.5 to 1.0
Sundance, without ClearRay100 to 150150 to 250Chlorine 3 to 4, or bromine 2 to 4
Bullfrog80 to 120150 to 250Chlorine 3 to 5, or bromine 3 to 6
Pool & Hot Tub Alliance, for any other tub60 to 180, ideally 100 to 120 with dichlor or bromine150 to 250 here (its own band runs to 1,000)Chlorine 2 to 5, or bromine 4 to 6

Two of them don’t square up. Sundance says its range without ClearRay comes from the Pool & Hot Tub Alliance, but the Alliance’s own bromine fact sheet gives 4 to 6 ppm for spas, not 2 to 4. And Hot Spring’s and Caldera’s manuals give no bromine range, apart from one start-up line in the Hot Spot manual that says 1 to 2 ppm, so a Hot Spring or Caldera tub on bromine gets the Alliance’s 4 to 6.

Questions about the log

Where is my log kept?

In your browser, on your device, and nowhere else. There is no account and nothing is sent to PoolBuff or anyone. The same goes for the volume the calculators save. Clearing your browser’s site data deletes the log, so save a copy now and then.

Why should I add the log to my Home Screen?

On an iPhone, Safari deletes a site’s saved data after seven days of Safari use without a visit to it, and a Home Screen web app is exempt. That is in WebKit’s own tracking prevention rules. Add it before your first test, because the Home Screen app keeps its own storage and does not see what Safari saved.

Why does the hot tub log ask who made my tub?

Because the makers disagree, and each manual says to follow its own figures. Hot Spring and Caldera want alkalinity at 40 to 120 ppm and calcium at 75 to 150. Jacuzzi and Sundance want 100 to 150 and 150 to 250. Bullfrog wants 80 to 120 and 150 to 250. Any other brand gets the Pool & Hot Tub Alliance’s ranges, which Jacuzzi and Sundance also point to.

Why doesn’t it say how much chlorine or bromine to add to my hot tub?

Spa chlorine and bromine are EPA-registered pesticides, and their labels say it is a violation of federal law to use them inconsistently with the label. Strengths differ between products, so the log gives the range to aim for and leaves the amount to your product’s label. The label also gives the highest level you may get in at. Leisure Time’s Spa 56 label, for example, prohibits re-entry above 5 ppm, and its directions for pre-measured packets say not to get in above 3.

Why are the hot tub doses in grams rather than teaspoons?

Because a teaspoon of pH decreaser or calcium increaser weighs different amounts depending on the granules, and a weight is exact. A kitchen scale reads grams. Baking soda is the exception: USDA weighs its teaspoon at 4.6 g, so that dose comes in spoons too.

How do I move my log to a new phone?

Tap Save a copy on the old phone. That downloads a spreadsheet file with every test, which you can open in Excel or Numbers too. On the new phone, open the log, tap Bring back a copy and choose the file. Each row carries the details it was tested under, so both the pool and the hot tub come back.

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