Okay so goldfish are dirty, but to the point of where two power filters and a canister are needed. I've never heard that before. I have had one of my goldfish for 4 years. I have a common goldifish in my 20gallon tank now and I use one power filter, it is a Marineland 150 Power Filter and it keeps his water crystal clean and clear. Yes he is outgrowing it but everywhere else i have checked so far has said that a 55gallon will work quite well for three goldfish.
*Although in keeping goldfish (any fish) it also depends on your own water quality to begin with.
Why ask for advice if you've already done the research and gotten the answers you wanted?
Just because your water is crystal clear does not mean it's adequate. How big is he? Size is a major factor in how much filtration you need. What are your water parameters? The waste goldfish produce that is the major problem is not visible. They also produce waste besides ammonia/nitrites/nitrates that isn't detectable, of course this can't be removed with the filter, only water changes.
I can only say what I personally would do, but I always keep 2 or more filters on a tank because if one fails your fish are possibly dead, especially if you're not at home for awhile. Also, on a 55 you have a lot more water volume to turn over than on a 20g. One emperor 400 just may not turn the water over enough to keep up with the waste from 3 goldies.
With one filter you also end up with dead spots, and if you do use one filter I'd suggest lots of bubbles or maybe a small powerhead. This will lessen the problem of too little surface area, something goldfish REALLY need.
Only YOU can know exactly what filtration will work for your fish, the size of goldfish largely depends on the fish. You can have a 24 inch comet or one that doesn't get over 10 inches. You may have a foot long common or one that doesn't get over 6 inches. Test the water parameters daily to see how the filters are keeping up.
Filtration is largely a personal decision, this is what I PERSONALLY would do, I always like to have extra filtration for ANY fish. Going with the minimum filtration I can possibly get away with is not something I try to do. "Overkill" filtration is not a problem unless it is impeding your fishes movement, underfiltration is.
If you don't want to buy more than one filter, then it is your personal decision to try the tank with just that one filter. If the water parameters are a problem you can always add more filtration later.
Ask 10 people on this website what filtraiton you need, you will most likely get 10 different answers.
jmulrich said:
Actually sand would be great for goldfish as i've done some more research. Becuase all the dirt and poo and food of all sorts settles right on top as I have been told elsewhere. So sand would work quite well for such a "dirty" fish as goldfish. Yes it may be tricky to siphon, but there are ways of easily cleaning up, it just takes practice.
I currently have 4 tropical fish tanks with sand, believe it or not one of them is a 55g with african cichlids (diggers). Yes the waste does sit on the top, but when you go to siphon it falls down in the sand and it is nearly impossible to get all of it out. Also, if you have fish that like to dig in the substrate for food, such as goldfish, they WILL push their waste down into the sand. I have this problem with my corycats.
Good luck!