I am aware that TT can do wonders but I have a problem introducing this option to my current setup. I cannot have a big TT, since my pot of goldfish is consider miniature. If I have a small TT, will it work? Currently my filter is made of a planter box and it is rested on a shelf about 18 inches from the floor, just 6 inches higher than the pot. Can you advise me what is the best size TT for my setup?

Regards,
Loke