I have done some changes to the tank:
1. I removed the coral gravel in the hob filter, my GH was more than 11 and continued increasing. The KH that i wanted to increase was still low, less than 1.
2. I removed the aquaclear hob filter, it was making a terrible rating noise. I tried everything to get rid of the noise, cleaning the rotor/motor/impeller housing, Changing the impeller , greasing the impeller aksel rod. Nothing helped, i guess just some of the hos just are noisy beacuse of their constructing.
3. I replaced the aquaclear with a very small internal powerhead. It have a small sponge but i will mainly rely on the plants to filter the tank so it is most for the water movment. I have used theese small chinese filters in other tanks, they are great, very cheap, very small , dead silent and none have yet broken down.
4. I have planted some more plants beacuse of removing the filter.
5. I also have started a diy CO2 system to help the plant out a little. Using a cig filter and the small powerhead diffusing the CO2 , works perfect.