I have a 100 litre tank stocked with one 5 inch goldfish, and several live plants. I need to buy a new filter, can anyone recommend a decent, cost effective filter? Preferably i'd like it to be hang on the back, with plenty of room to fill it with my own media. I really don't want a canister filter because i'm afraid it will leak and I really don't have anywhere to put it. I've heard that for goldfish you need a filter that can handle quadruple what it says on the box ( as most filters can handle about half what they say and goldfish need double the filtration compared to other fish ). I'm honestly getting incredibly frustrated trying to find a filter that will fit my needs which is why i've turned to forums for advice. I think it needs to have a flow rate of 1000 to 2000 litres / h, and a capacity to hold 1.5 - 2 kg of bio media. I'm on a budget so if possible i'd like to spend under £40, I only want to be running a single filter and I would prefer it to require no cartridges and have a nice big open square compartment for media. I would like to maximize surface agitation. Adjustable flow rate would be a bonus. Is there even a filter out there like this or am I going to have to use two filters / a canister filter. Any advice is welcome, I would be more than grateful.
I'm afraid you won't find a HOB that can do that kind of performance, unfortunately. You're really going to have to consider a canister filter to get what you need for a goldie. Eheim classics are good value, reliable and easy to use and I've never had one leak (I have 5 of them).