Pool chemical dosing calculator template

Free build guide: Pool chemical dosing calculator for WordPress

This guide rebuilds the Pool chemical dosing calculator from this site in Gravity Forms: 8 inputs, 4 live results and no submit button. Expect about 36 minutes by hand. The template above is the same form as an import file, and the bundle adds a PDF version of this guide with a screenshot of every setting, plus the stylesheet.

You will end up with:

• Chlorine to add
• Shock dose (raise 10 ppm)
• Muriatic acid to lower pH (fl oz)
• Baking soda to raise alkalinity (lb)

What you need

• Gravity Forms (any license) — Calculation fields and drop-down values are in core.

Everything here is core Gravity Forms. No add-ons.

1. Create the form

1. Go to Forms → New Form and name it Pool chemical dosing.
2. In Form Settings → Form Layout, set the CSS Class Name to fo-live-only. Step 3 uses it to hide the submit button.
3. Leave the form open in the editor; the fields come next.

2. Add the fields, in this order

Field IDs are assigned as you add fields. If yours come out differently, change the {Label:ID} references in the formulas to match your IDs. Settings not mentioned stay at their defaults.

1. Pool volume (gallons) · Number · ID 1
Number Format 9,999.99; Default Value 20000; Description “The Pool volume calculator on this site works it out from the dimensions.”.

2. Free chlorine now (ppm) · Number · ID 2
Number Format 9,999.99; Default Value 1; Description “From a test strip or kit.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

3. Target free chlorine (ppm) · Number · ID 3
Number Format 9,999.99; Default Value 3; Description “2–4 ppm for a residential pool; higher with cyanuric acid above 50.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

4. Chlorine product · Drop Down · ID 4

Choices (tick show values and enter each value):

• Liquid chlorine 12.5% (fl oz) — value 10.7 (selected by default)
• Household bleach 6% (fl oz) — value 21.3
• Cal-hypo 65% granules (oz by weight) — value 2
• Dichlor 56% granules (oz by weight) — value 2.4
• Trichlor 90% (oz by weight) — value 1.5

5. pH now · Number · ID 5
Number Format 9,999.99; Default Value 7.8; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

6. Target pH · Number · ID 6
Number Format 9,999.99; Default Value 7.5; Description “7.4–7.6 is the range.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

7. Total alkalinity now (ppm) · Number · ID 7
Number Format 9,999.99; Default Value 60; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

8. Target alkalinity (ppm) · Number · ID 8
Number Format 9,999.99; Default Value 100; Description “80–120 ppm keeps pH steady.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

9. Chlorine to add · Number · ID 9
Number Format 9,999.99; Description “In the unit shown for the product. Add with the pump running, in the evening, and retest after an hour.”; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 1.

( {Target FC:3} - {FC now:2} ) * ( {Volume:1} / 10000 ) * {Product:4}

10. Shock dose (raise 10 ppm) · Number · ID 10
Number Format 9,999.99; Description “For algae or after heavy use. Keep swimmers out until chlorine drops below 5 ppm.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

10 * ( {Volume:1} / 10000 ) * {Product:4}

11. Muriatic acid to lower pH (fl oz) · Number · ID 11
Number Format 9,999.99; Description “31.45% acid, about 8 fl oz per 10,000 gal per 0.1 pH at normal alkalinity. Add half, wait, retest. Negative means pH is already low.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

( {pH now:5} - {Target pH:6} ) * 10 * 8 * ( {Volume:1} / 10000 )

12. Baking soda to raise alkalinity (lb) · Number · ID 12
Number Format 9,999.99; Description “1.5 lb per 10,000 gal raises alkalinity 10 ppm. Negative means it is already high.”; Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 1.

( {Target TA:8} - {TA now:7} ) / 10 * 1.5 * ( {Volume:1} / 10000 )

3. Hide the submit button

The results are live, so nothing needs submitting. Add this filter to your theme’s functions.php or a code-snippets plugin; it hides the button on any form carrying the fo-live-only class:

add_filter( 'gform_submit_button', function ( $button, $form ) {
	return str_contains( (string) rgar( $form, 'cssClass' ), 'fo-live-only' ) ? '' : $button;
}, 10, 2 );

Or with CSS alone: .fo-live-only_wrapper .gform_footer { display: none; }

4. Put it on a page and make it look like this

Add the form to any page with the Gravity Forms block, or the shortcode [gravityform id="X" title="false" ajax="false"]. The form inherits your theme’s styles; the classes you set in step 2 are hooks for the look you see on this site:

• fo-result on a calculation field makes it the big teal result panel.
• fo-result fo-result--sub makes the smaller secondary figures.
• fo-segmented on a radio field turns it into a segmented switch.
• Two fields on one row is the editor’s own column layout: drag a field beside another and the row splits in half. No CSS class is needed, and the old gf_left_half Ready Classes are deprecated.

The bundle includes the two stylesheets that implement those classes, with notes on matching your brand colours. Without them the form still works; it just looks like your theme’s default Gravity Forms styling.

How the maths works is explained under “How it’s calculated” on the live Pool chemical dosing calculator.