Thanks for your answer
Yes a I agree about the substrate, I Will tray to change it by silce sand, I think that is the best for aquariums, right?
I will try to remove as many gravel as I can, I still want to let the home made substrate for plants, because I would like to have some plants, specially Annubias (the do not require too much light).
I am also changing the filter to reduce the current and have a timer for the light. I am almost ready to bring the axies.