For anyone else..the conversions
...40L is a hair over 10 gallons; 10kg is about 20 pounds.
If you have only been running a week you probably aren't cycled as yet..it takes a good 4 weeks with 6 being normal. Are you planning a setup with fish and liverock only or are you planning on adding corals as well?
You are probably over in the amount of liverock and sand you need. Recommendation would be (rounded up) about .7 kg/1.5 pounds of liverock per liter/gallon of water. Depending on what you plan on keeping, you only need about half the sand you are currently using and even that isn't strictly necessary..it is more for looks. There are many people who keep a reef in a bare bottom tank.
The better test kit I think any of us have found is the API Master Reef Test Kit. Depending on what is available in your area, the best test kit to get is a liquid test kit..the testing strips don't give an accurate reading. At a minimum right now you need tests for High Range pH, Ammonia, Nitrite and Nitrate. If you are going to run a reef tank, once you get things established you will then need Phosphate, Calcium and Water Hardness.
You also want to be able to check your salinity level. You can use the standard hydrometer or better is a refractometer. The refractometer is going to give a more accurate reading.
The one thing you need for a new marine setup is patience as it takes a little longer to get the marine tank stabilized for inhabitants.