River Rinža in Municipality of Kočevje suffered from massive fish kill. Civil protection has took over responsibility in order to find the best solution for the situation, and that in the future forestall such events. After they contact us and explained the issues of requiring the oxygen on river Rinža as soon as possible, we took all information into account and propose the best solution for their current situation and decided to take part in solving the problem.

On base of preliminary results of oxygen level in the water, which we took before setting the testing turbine TT200, we realized that the river had enough oxygen at the surface, while the situation on the bottom was completely different. After turning on the testing turbine TT200 and its continuous action, on the basis of laboratory tests, we realized that our preliminary reviews were accurate and that there is no load on the river in terms of pollution. However, our first assumption regarding the lack of oxygen at the bottom proved to be correct, and that is the crucial thing in terms of normal fish environment.

After comparing the results, we realized that the problem of massive fish kills is probably caused by sludge mixed on the bottom of the river due to the sudden movement of the fluid, and therefore lack of oxygen in the whole river.



The river has a long stream and is partly dam prevented. Upstream of the dam at the bottom there’s a lot of wrinkled sludge, which is the biggest problem of oxygen supply to the fish. By nature, the fish spend most of their time on the bottom so it’s a vital that the bottom of the river have enough oxygen. This problem needs to be addressed quickly and efficiently, so that we act preventively in order to prevent the catastrophic situation as it was this summer.

The level of oxygen to the bottom of the river Rinža (particularly in the mud) was virtually nil. However, with the involvement and action TT200 turbine oxygen levels at the bottom reached 8,5mg/l. Fish in the river stream began to circulate around the aerator for mixing water and a sufficient amount of oxygen. The testing turbine TT200 therefore had a twofold effect, first to the sludge at the bottom which started to get enough oxygen and other that fish began to receive enough oxygen at all depths of the river within 30-40m diameter from aerator (although not visible).


Turbine TT200 has proven to be very effective when it comes to injecting oxygen at the bottom of the river Rinža, specifically in the sludge. Tests on the river found that the turbine doesn’t need more than three minutes to bring over 8 mg/l of oxygen directly into the mud, which is more than enough for unimpeded fish life. According to the expert analysis of the entire river, we found that the best solution for the river Rinža and the municipality Kočevje itself that from the beginning of May until the end of September set along four Toring turbine FATT200B setups at most critical points, so that the fish have a some sort of “safe house”. The area covered by an aerator is about 30-40 meters in diameter, depending on the configuration of the bottom of the river. In that way we could prevent possible new massive fish kills by placing setups before hot summer days.