Have you used a 3D CAD program to draw and accurately calculate your pool volume? Which program did you use?

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Gary Davis

Gary Davis

Well-known member
Aug 29, 2022
186
Modesto, California
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
Have you used a free 3D CAD program to accurately draw, model, and calculate your pool volume?
Which free program did you use?

Googling, I see that Blender is a well-known well-supported cross-platform FOSS 3D CAD program which can be used to model pool dimensions.
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What free CAD software did you use to draw & model your pool for your own personal use?
 
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Want to hear something ridiculous?

I imposed the shape of my freeform pool from googlemaps satellite view onto an excel spreadsheet and reduced cell size so they acted like pixels. Then used some formula approximations for depth at each pixel.

Dont laugh it worked
 
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You can truck in water and look at the bill for total gallons.

Test, and adjust FC, test again 30 minutes later. Use "effects of adding" in pool math, enter what you added, then adjust pool volume until the increase in FC (After FC test - before FC test) matches your test results.
 
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sbcpool said:
If your pool is visible in satellite photos you can use a tool at www.gpsvisualizer.com/draw to measure the area of a polygon. Then you just multiply by your average pool depth to get cubic feet. Finally, cubic feet x 7.48 = gallons.

5jQQJPl.png
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Navigate to Google Maps and search for your location.

Click “Layers” to see satellite imagery. Use plus sign to zoom in on your site.

Right click on map and select “Measure distance.”

Click on map repeatedly to draw polygon around area you would like to measure.

Close the shape and Google Maps will automatically show the area measurement within the polygon.
 

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For example, if the perimeter is 120 feet, the maximum area is 1,145.92 square feet, but the minimum can be almost 0.

A circle with a diameter of 38.1972 feet will have a surface area of 1,145.92 square feet.

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A 20 x 40 rectangle has a surface area of 800 square feet.

A rectangle of 1 x 118 feet has a surface area of 118 square feet.

A rectangle of 0.1 x 119.8 feet has a surface area of 11.98 square feet.
 
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JamesW said:
That will give you the perimeter, but not the area.
Click to expand...

I should have been more clear. Measure like this:

area-s.png

For each yellow line, multiply the length of the line by the distance between lines, and then by the average depth along that line. That will give you the volume of an approximately rectangular slice of the pool. Then sum all the slices to get the total volume.

If you're lucky enough to have rectangular tiles around your pool as in the photo, you can probably do all the measuring and calculating in like 15 minutes. If not, you might need an additional 4 or 5 minutes to lay out two parallel strips of painters tape and mark them off in regular intervals. The depth measurement will be easiest if you have a friend in the pool with a second tape measure.
 
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ajw22 said:
There is also a Chemical Way of Calculating Pool Volume using an alkalinity test kit, sodium bicarbonate or acid, and the formula.
Click to expand...
Thanks for that wonderfully easy-to-perform alkalinity + acid/base-titration volume-calculation method, which I will definitely use as I need to add immense amounts of acid anyway as I'm refilling my pool with very high alkalinity well water as we speak. Hence, I wouldn't want to add any sodium bicarbonate; but I will need quite a few cases of HASA 31.45% HCl (at $46.98/case taxed, or $11.75/gallon, taxed) anyway - so I will definitely run the suggested acid test to titrate the pool volume.

Multiply 125,000 (which is the formula number for Muriatic Acid) times the number of quarts of acid added, divided by the ppm reduction in alkalinity caused after circulating the water for a few hours (being extra careful to not add too much acid at one time - where - generally, it is safe to add four quarts of acid per 40,000 gallons of pool water when the TA is over 160 ppm and the pH is above 7.7. Four quarts of acid will lower the TA by 12.5 ppm per 40,000 gallons.​

Even so, the whole point is to have a 3D CAD model of the pool, where I have already measured everything and calculated the volume but the point isn't so much to calculate the volume as to play with the CAD software - mostly for the sake of the beauty of learning how to use CAD software - which - is more fun when there is a specific end goal in mind.

BTW, I'm an aspy, so if I can calculate the volume down to the milliliter (aka cubic millimeter) - that would make me very happy before I die.

trivetman said:
Now that we’ve give u all sortsa answers, why are you asking about this?
Click to expand...
That's a good question where I think I wasn't clear that certainly I can calculate the volume of a pool using basic arithmetic (as shown in the sequential attached images) but I want to learn how to use a CAD program with a real-world example - which - can then be easily honed such that all sorts of good things can happen when you learn how to design things yourself.

Suffice to say, the intent of this thread is that a CAD-specific thread is something this forum should have (IMHO).

So the goal is more about using the CAD program to model the pool than about calculating the volume of that pool - where - the point of asking here is I can't be the first person on this forum who wants to use a CAD program to model their pool. Right?

Looking up common free CAD programs, these are those that I found so far (for Windows) that I've downloaded and will see which ones are worth testing for laying out a pool (where others can also make use of my findings).
Of the dozen Windows CAD programs above, I think I'll try out Blender and/or Inkscape with Fusion360 first - based on the results of my Google searches. But the whole point of asking this question in this thread is to get a head start on which 3D free CAD program most of you prefer to use to model your pool.

The main advantages, as I see it so far anyway (which is why I'm asking here for advice from those who have done it) are:
  1. Blender - very well supported free cross-platform CAD with many tutorials (including for pools)
  2. InkScape - also very well supported - but specifically it supposedly does 2d to 3d photometry from a JPEG image
  3. Fusion360 - where, supposedly, InkScape converts 2D JPEG images into 2D SVGs which imports to Fusion360
If nothing else, this thread can serve as a useful reference for others - which is why I'm laboriously adding all the detailed links.
The advantage, if this thread is productive, to the group at large might be:
  1. Pool owners can easily model their pool in Blender freeware on any platform
  2. Pool owners can convert a flat 2D JPEG image of their pool with InkScape to a Fusion360 3D model
If we accomplish that, this thread will have been worth the effort the team expended on fleshing it out.
 

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I used Fusion 360 to model my pool to calculate the volume. I took lots of measurements of everything during refurbishment when it was empty. I also took hundreds of photos and used photogrammetry software to create a 3d model that could then be sized correctly between known points to calibrate the model.

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While this thread is all about using free CAD software to model your own pool, the simple arithmetic volume math gets a lot easier once the entire multi-sloped bottom of the pool is filled with water (which eliminates some of the uncertainty in the oddly shaped calculations).

You end up mostly with two main calculations:
  1. Measure the volume needed to cover the sloped sections
  2. Calculate the volume of the simpler-shaped top section
Using only one garden hose (so as to not overstress the well pump and water pressure booster pump) for 30 hours x 8 gallons per minute (over 6 days elapsed time) ends up being about 2,500 gallons per day for a total of about 14K gallons in the variously sloped sections.

Now that the water covers all the variously sloped sections, the remaining rectangular box above the pool is more easily calculated at 60 feet long by 15 feet wide by about 36 inches left to fill, for about 20K gallons. This latest (simplest) two-part estimate of pool volume comes up with the lowest amount yet, of about 35K gallons (give or take).

There's a bit of slop in where to count the fill line, where every inch that is off is a bit over 500 gallons of water so we have to be careful of sig figs.
 

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