hi guys hope you can clear some thing up for me. ive had a hunt around and come up with different information regarding how often too water change a new set up. the set up is a 120l high tec with plain cat litter as the substrate and an old filter light is hard to gauge im using a 50w 40 degree spread halogen suspended 500mm from the water surface. ferts are EI levels with easy carbo after the water change and when i get home co2 is silly high. for the first week i changed %50 every day the second week i changed %50 every other day. now im on the third week im unsure how often they need to be done.ive learnt the hard way stability is key, so don't want to over do the water changes. so far no algae but not much growth. any thought's appreciated. thanks