Yes, that didn't mean anything to me, so just now I searched and eventually found some refs to the tank kit. Its still not anything I've ever heard of or seen but of course that's not saying much as I'm in the US. Perhaps there are UK members who might have had one of the filters from an Aldi kit and could comment, I don't know. I know that Fluval make a good internal but I don't know how that would compare with the Aldi filter. Its important that a filter not allow large amounts of water to "leak" by the media or media containers. Otherwise it can be difficult to build up large bacterial colonies, particularly on a timely basis. I don't know if that's your problem but its possible. Unfortunately, not ever having had my hands on one, I'm not really the one to comment. As OM commented earlier though, you are far from having no colonies.. you've got colonies in there but the overall capacity seems to be having difficulty ramping up to size.
~~waterdrop~~
