Pool Caculation & Sizing

[Daniel.Kaw]

Here I post up the calculation that we usually used to size up our pool, balancing tank, pumps and filters. I'll note them down in section and update them accordingly.



POOL SIZE
When we talk about pool size, be it a swimming pool, wading pool, jacuzzi, water feature, or bio pond, the pool size calculation is always standard - Area multiple by the pool depth = Volume.

If you got inconsistent pool depth, you can take an average, which will give an estimate, or you could take the various area of the pool whereby the depth is different.

The area and volume are 2 main element for the entire pool sizing for equipment.



Turnover Rate
The turnover rate for a pool is the amount of time required to circulate the entire volume of water through the filtration system once to meet reasonably clean, safe water standards.

The design turnover rate is
(A) Six (6) hours for swimming pool
(B) Three (3) hours for Jacuzzi or Children (wading) pool
(C) Two (2) hours for water feature & Bio pond

Based on the pool’s capacity and the desired turnover rate, the minimum rate at which the water must be circulated in Liters Per Minute (LPM) is calculated as follows:
Pool Volume (in liters) ÷ Design Turnover Rate (in minutes)

With the above, you will get your desired Filtration Flow Rate, which can be used to size up your pumps and filters.

[Daniel.Kaw]

Lets put in a simple design and perform some calculation to further understand the requirement of each individual element that will affect the pool calculation and sizing.


TYPICAL POOL
Lets assume we are sizing up the necessary equipment for a lap pool of size:
Length - 20m
Width - 8m
Water Depth - 1.2m (for public pools, any water depth that is 1.5m or more will required a full time life guard)

We assume that the design is an overflow system with full parameter scupper, hence a balancing tank for returning water collection is needed. The size of the scupper is design at 250mm wide and 350mm deep.

With the above, we are ready to do our math.


Pool Area & Volume
Pool Area - 20m X 8m = 160sqm
Pool Vol - 160sqm X 1.2m = 192cum

Turn Over Rate
Normal Lap pool turn over is base on 6 hrs
We mentioned that we need the formula to be in Liters per Minutes, hence we will convert the cum to liters and hours to minutes.

Turn Over Rate - (192 X 1000) ÷ (6 X 60) = 533.333~ LPM
We round it to 540LPM

So we now need to find a filtration pump that can generate 540LPM volume of water.

[Daniel.Kaw]

Once you found a suitable pump to run 540LPM, now we need to size up a filter.

Read HERE to understand more about what kind of filter you can choose from.

Which ever filter you choose, usually Sand and DE filter for swimming pool, there are some thumbs-of-rules for calculation.

Thumb of rules:
Design flow rate of Sand Filters - 600lpm per m²
Design flow rate of D.E. Filters - 100lpm per m²

The formula used to size up a filter would be:
Volume of pool / flow rate of filter (design rate)

We know that our pool is 192cum and we decide to use a sand filter, hence we should get:
192 / 600 = 0.32 m²

If you wish to use a DE Filter: 192 / 100 = 1.92 m²

[Kenith Soe]

Once you found a suitable pump to run 540LPM, now we need to size up a filter.

Read HERE to understand more about what kind of filter you can choose from.

Which ever filter you choose, usually Sand and DE filter for swimming pool, there are some thumbs-of-rules for calculation.

Thumb of rules:
Design flow rate of Sand Filters - 600lpm per m²
Design flow rate of D.E. Filters - 100lpm per m²

The formula used to size up a filter would be:
Volume of pool / flow rate of filter (design rate)

We know that our pool is 192cum and we decide to use a sand filter, hence we should get:
192 / 600 = 0.32 m²

If you wish to use a DE Filter: 192 / 100 = 1.92 m²

Hi ,
I think that your calculation of Filter szie was not correct.
Answer of filter area would be 0.9 m2.
Please can you review for it??
As I understand that sizing of filter shall calculate with Pump Flow rate/Design flow rate of Filter.
If i was wrong, please correct me.

regards,

Kenith