### Step 1: Calculate Total Tank Volume

Many tanks (other than most concrete tanks) have a marking to show the total volume of the tank. If you know the volume of your rainwater tank go to Step 2.

- Using a measuring tape and a ladder, measure the height and the radius of the tank.
- Enter these numbers into the volume calculator to find out the total volume of your tank in cubic metres.
- Multiply the result by 1000 to find the total number of litres your tank holds.

### Step 2: How Much Water Is In My Tank?

You may be able to tap on the side of the tank and listen for a significant change in sound between the empty section and the full section to determine where the line is, which you can then measure from the bottom of the tank. If you are unable to accurately tell using the tapping method try the following:

- Use a long piece of dowel or something similar to dip into the tank end drop one end all the way to the bottom. Try to do this carefully so that the stick remains perpendicular to the bottom of the tank for an accurate reading.
- Measure the length of the section of the stick which is now wet.
- You can then divide the total volume by how much water you actually have in your tank.

Alternatively, you can simply enter the height of the water level instead of the height of the tank in the volume calculator along with the radius.

- Remember to convert the figure obtained from the volume calculator from Cubic Meters to Litres multiply this figure by 1000.

### Step 4: HydroSil ULTRA Dosing Instructions

We recommend using rubber gloves and safety glasses while handling HydroSil ULTRA.

The amount of HydroSil ULTRA required depends on how soiled the water is. Below are two suggestions for Initial Dose. Depending on how soiled your water is you may choose an amount somewhere in between.

**Initial Dose – For Water Without Noticeable Odour or Visible Contamination**

(24hrs contact time required before drinking)

200ml per 1000L of water

1L per 5,000L of water

2L per 10,000L of water

4L per 20,000L of water

**Initial Dose – For Badly Spoiled Water (Shock Dose)**

(24hrs contact time required before drinking)

300ml per 1000L of water

1.5L per 5,000L of water

3L per 10,000L of water

6L per 20,000L of water

**Monthly Maintenance Dose
**(Water can be drunk immediately)

70ml per 1000L of water

350ml per 5,000L of water

700ml per 10,000L of water

1.4L per 20,000L of water