Lotus Clean Calc Down Pad

Lotus Clean Calc Down Pad
  • EWC1050

Why should the water be softened?

  1. Hard water is prone to lime precipitation. Lime deposits in the pipes lead to deposits and biofilms.
  2. Lime deposits can reduce the service life of the heating.
  3. Hard water leads to strongly increasing pH values which can only be lowered with a lot of pH minus. The constant lowering of the pH-value costs a lot of time and is expensive.
  4. Hard water with a high pH value can lead to clouding of the water.
  5. Hard water reduces the effectiveness of water care products.

How do I determine the hardness of the water?

Ask your water supplier about the hardness of your water. Let him give you the total hardness in degrees of english hardness.


You can determine the water hardness yourself with our Water Hardness Test Set.

How do I determine the hardness of the water?

Fill the measuring cup with 5 ml water from the spa. Now add the measuring liquid drop by drop. Shake the liquid after each drop so that the water and the measuring liquid mix. The water turns red. Count the drops you add. As soon as the water turns green, you have determined the degree of hardness. Each drop corresponds to 1 degree of German hardness. If the water in the measuring cup changes colour from red to green with 10 drops, you have a water hardness of 10 degrees German hardness.

How many Calc Down Pads do I need?

This depends on the water hardness* and the water content. Use this table as a guide. The information relates to 1,000 liters. ( A Calc Down Pad has a weight of 0.8 kg.)

Starting hardness: 15  20 25  30  35  40  45  50  55 
Target hardness                  
 5  1,1 kg 1,7 kg  2,3 kg   2,9 kg  3,4 kg  4,0 kg  4,6 kg  5,1 kg  5,7 kg
 7  0,9 kg  1,5 kg  2,1 kg   2,6 kg  3,2 kg  3,8 kg 4,4 kg  4,9 kg  5,5 kg 
10  0,6 kg 0,9 kg  1,5 kg  2,1 kg  2,6 kg  3,2 kg  3,8 kg  4,3 kg  4,9 kg 
12   0,3 kg 0,9 kg 
1,5 kg  2,1 kg  2,6 kg  3,2 kg  3,8 kg  4,3 kg  4,9 kg 
15   0,0 kg 0,6 kg  1,1 kg  1,7 kg  2,3 kg  2,9 kg  3,4 kg  4,0 kg  4,6 kg


You have a water hardness of 30 and want to reduce the water hardness to 12. Your spa has a water volume of 1200 litres. You then take 2.1 kg and multiply it by 1.2 (1200 litres). Result: 2.52 kg. You divide the 2.52 kg by 0.8 kg (weight of the Calc Down Pad) The result is 3.15. In this case you need 3 Calc Down Pads as one pad contains 0.8 kg softener mineral.

You can also take 2 Calc Down Pads and soak them (when the water hardness no longer decreases) for a few days in distilled water with 30% salt content. This removes the calcium ions from the softener mineral and replaces them with sodium ions. The Pads can then be reused.

What is the ideal water hardness in a spa?

The ideal water hardness is between 7 and 10 degrees of German hardness.

Where should the Calc Down Pads be placed?

A good flow is important for a fast and effective softening of the water with the Calc Down Pads. It is best to place them in the filter chamber. For spas without a filter chamber, the Calc Down Pads should be placed directly on the filter. It may be useful to increase the filter running time during the softening period.

How long does it take to soften the water?

This depends on the water hardness, the number of Calc Down Pads used and the flow rate. It can be from one or two days to two or three weeks.

Can I use the Calc Down Pads more than once?

This is possible. To do this, you must place the Pads in distilled water with a salt content of approx. 25% after use. This corresponds to about 360 grams per litre at room temperature. This will regenerate the Pads. A higher salt content is not advisable, as the salt solution is already saturated at 26% and further salt would no longer dissolve. Be sure to use dishwashing salt for this purpose, as other salts have a so-called anti-caking agent added (e.g. calcium carbonate or magnesium carbonate).  

How do the Calc Down Pads work?

The Calc Down Pads contain a special mineral which is charged with sodium ions. These minerals release sodium ions in the water and absorb calcium ions. This makes the water softer.

I have a water softener in my house. Do I still need the Calc Down Pads?

Yes, a domestic water softener can only soften a certain amount of water at once. But never as much as fits in a spa Once the target water quantity has been reached, the exchanger granulate in the water softener would have to be regenerated. However, since much more water is allowed to run continuously through the water softener, unsoftened water also ends up in the spa after the target water quantity has been reached.

How do I measure the hardness of my water after using the Calc Down Pad?

To measure your current water hardness we recommend the Lotus Clean Total Hardness Test Kit.

Product information "Lotus Clean Calc Down Pad"
Category Watercare: Water hardness & pH-value
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