unfired red clay in substrate
I recently setup a 55g planted tank. For the substrate I used 2 bags of fluorite and red unfired red clay about 1lb to 2lbs and capped with gravel so its about 3to 4 inches thick is some areas. I have had the tank running with a filter off another tank so its fully cycled. I noticed when I do the water changes that on the surface theres kinda oily residue, is it off the clay? because I haven't added another water fertilizers. I also have a red Indian sword which the new leaves arent so red.. more greenish with red spots same with the red rotella there is tons of new growth but its all green not red , was the clay a good choice to add? should i get root tabs to add in?
thanks for any posts!