I have a 29 gallon biocube that I purchased from someone. I have had it for a year. I had my local fish store come out and look at it and tell me what if anything I needed to do to it so I wouldn't dump a bunch of money into it and have something go wrong with it. I had bristle worms out the ying yang. He told me I should replace most if not all of the sand, so I did. I now am having soooo much trouble keeping red slime out of my tank I think I have it all about gone and then it blooms again. So if any suggestions on that that would be a big help. I have recently put in an extra water flow and that doesn't seem to make any difference. I have a friend who has a 55 gallon tank who said I could have it, but I am wanting to know what all I would need to get that running, filters and lighting etc. I have read and it says the bigger the tank the easier to maintain. Please help I love doing my fish tanks but this is getting frustrating!!!