How do i clean the tank???

Question
QUESTION: Hello, I have just got goldfish, the tank is so dirty and water is cloudy, can you plese tell me what the best thing to do is?
Thanks

ANSWER: Hello Clare:  How big is your tank... and how many goldfish do you have.  Goldfish are very dirty fish... so the best way to clean the tank it so gravel vacuum out about 20 percent of the water.  Goldfish almost need to be over filtered in their tank because they are constantly looking for food... which brings me to feeding... only feed your goldfish what they will eat in about 3 minutes... I feed my fish twice a day morning and evening and rarely anything in the mid-day.  Goldfish are constantly looking for food so don't be fooled by their begging... they would eat themselves to death if you let them... I hope this helps... keep me posted please on your water progress... dave

---------- FOLLOW-UP ----------

QUESTION: hello, the tank is probally 14" long x 10" high x 10" wide. i got a pleco and 3 goldfish. the sponge in my filter is always blocked with slim. i really feel i need to start again as its so dirty, you cant see the fish in the water its that dirty. i really dont know what to do?
Thanks clare

Answer
Hi Clare:  well you have managed to pick two of the dirtiest fish around... goldfish and plecostomus... Your tank is small probably a 5-7 gallon tank and that is about the size for one goldfish.  This is probably why you are having such a problem with dirty water.  You can either purchase a larger tank... or you should consider taking your fish back to the aquarium and trading them for something else like guppies or molly's, etc.  Please keep me posted... dave