TECHNICAL EQUIPMENT INFORMATION PAPER TEIP1/PR -03/09
Sand filters should be ‘back-washed’ to waste to dispose of debris taken out from a filter in its general working action, or debris collected from the pool vacuum heads or automatic floor cleaning gadgets that function via a filter unit.
Sand filters should be back-washed for a minimum of 5 minutes every 10 to 21 days in lightly used pools and for 5 minutes every 7 days in heavily used pools in domestic applications.
Commercial pools have different parameters & procedures.
A filter drum will hold the following approximate volume of sand:
15-16” size will hold 0.13m² (1.40sqft) with 1½” flow lines. Use 2 x 25kg of 16/30 grade of filter sand.
18-19” size will hold 0.17m² (1.85sqft) with 1½” flow lines. Use 3 x 25kg of 16/30 grade of filter sand.
23/25” size will hold 0.33m² (3.17sqft) with 1½” flow lines. Use 4 x 25kg of 16/30 grade of filter sand and 1 x 25kg of gravel (3-6 or 5-10mm).
30” size will hold 0.46m² (4.9sqft) with 2” flow lines. Use 6 x 25kg of 16/30 grade of filter sand and 2 x 25kg of gravel (3-6 or 5-10mm).
Sand filters in Koi pond applications should use 8-16 grade of filter sand.
Top mount valves are more practical than side mount. Because they take up less plumbing space and give more even pressure when in use.
How to use your multiport when back-washing is required.
Think of your valve face as a clock.
1. First turn off your pool pump.
2. At 12 o’clock you are in FILTER position (normal running).
Push valve handle right down to bottom –
This protects the valve sealing gasket against movement.
3. Turn your valve to 6 o’clock – BACKWASH position.
4. Turn on your pool pump to ‘back-wash’ as already advised.
5. Turn off your pool pump.
6. Select RECIRCULATION (20 to 8).
7. Turn on your pool pump for some 30 seconds only. –
You are only cleaning the valve body no need to waste water.
8. Turn off your pump and put valve back to 12 o’clock (FILTER position).
Now leave valve off for some 15 minutes to allow the sand to settle.
This process is called ‘Sedimentation’.
The heavier gravel falls first, the sand follows.
Useful in 24” & 30” filter drums.
9. The RINSE position (10 to 10) is useful to blow out any air
in the filter drum without lose of water.
10. WASTE (10 past 12). Here you can vacuum to waste to either drain the
pool or clean any unwanted effluent.
11. CLOSED is used during ‘Winterisation’ coverage or for use
in ‘flooded suction’ applications.
Tips
Disregard ‘sight glass’ – purely shows water is flowing.
Check that your valve pressure gauge is working correctly.
Use glycerine filled gauges. They are far longer lasting.
Check spider gasket inside valve body, & top ‘o’ ring once a year.
If your valve top assembly is well worn it is cheaper in time to fit a new top assembly only.
Always use PTFE tape when plumbing in internally threaded valve ports. Do not glue.
Providing you backwash regularly & chemicalise properly your filter sand will last for many years.
October 28th, 2010 at 9:57 am
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