hey scotty, you were lucky to be given a tank that big i wish someone would give me a big tank
anyway, lets start on these questions
that sounds like black brush algea. a good way to get rid if that would be to go to the LFS and buy a couple of siamese algea easters :lol:
I'm going to have to disagree with you there Caryl although this isn't personal experiance, i have heard alot of ppl say that plant fertiliser will actually kill algea don't take that as gospel though
I'm going to presume that hagan test kits are pretty good cause they are the most expensive, but i'm not going to recomend them when you can go into picies aquarium and get a ph test kit for $11
I'd say 20% a fortnight would be sufficient
cannister filters are usually classed as better filters because they have more media room. I would run both filters though as you can never have to much filteration (unless it is somthing crazy like a 2000lph filter on a 20l tank :lol: )
I think once a month is the norm....don't quote me on that though
one thing i'd like to add....
as crazy as it sounds, i htink your fish are getting sick because of the sudden cleaning they would have adapted to the dirty water and all this sudden cleaning has shocked them....making them sick....not much you can do about it now though
good luck