Water Changes?

[gh74]

yeah if there is more tanins in the tanks,i'll be doing %20-30 WC every 2-3 days

 

[gh74]

I did the %50 water change yesterday evening and this evening it is as bad as ever,so what is better to use purigen or carbon,do i just put the purigen in on top of the external and what about the carbon just i have a mix of 2 media's in the external so were would it go etc,i have a new external coming either tomorrow or wednesday,has a built in uv sterilizer and it can run up to 400 liters so would this make any difference,its not like tanin color as i have the bogwood out that was the main culprit for the tanin's in it previously,...also what would be causing the hose from the filter to get very dirty/algae just the hoses are nowhere near any windows for the light to be causing it,,,anyone any thoughts?
 
cheers