Ovo sam našla
Generally, there are two methods of usage.
1. The first is more complex but very accurate. Firstly, put the peat into a container with some water. Leave it for a few days while acidic materials are being extracted to the water. Next, measure the pH level of the water. It should vary from 4 to 5. Now, you can tip some of this water into your aquarium. Do it slowly, always tip in parts and measure the changes in the aquarium. This way of doing things is much more precise and safer than the second one, since you can control the water quality.
2. TThe second way is much more easier than the first one, however it is much more dangerous too. Put the peat into some stockings. If you have a small aquarium, immerse the stockings directly into the water. During the initial phase, the peat will float to the top. If you have a large aquarium, you can put the stockings with peat into a filter. Bear in mind, that it might cause serious damage to your tank if you don't control the process frequently!
How much and how often?
There is no exact answer. The main factor is the water that you want to adjust. As I mentioned above, I use peat from JBL and Sera. I put 250 g in 250 litres of water and I change the peat once every month when I clean the filter. Since I'm using it for short periods of time, the peat doesn¹t change the colour of water but it lowers the pH by 0.5. Leaving the peat in water for long periods doesn't result in any effect; the pH starts go up slowly.