Red Devil- water condition

Question
Hello!
   I have had my red devil cichlid "Coconut"  for about 6-7 years now and he's about 10'' in length. I know large tanks are highly recommended for these fish, but he seems to be doing just fine for the past 5 years in his extra high 30 gallon tank.He is highly destructive, and is always up rooting plants, gravel, and his hiding rock. My only problem is however, is that the water is almost impossible to keep clean and clear. I am using a power filter 'penguin bio-wheel 350' which claims to filter 350 gph, with 4 carbon filters and 2 biowheels. I add/change at most 10% water every week/every other week. Any recommendations on a different filter system, or should I definitely purchase a larger tank?  

Answer
Yes a bigger tank would be highly reccomended something like a 50 gallon long tank. Also do weekly water changes of 25% and change the filter inserts monthly and that should keep the tank clean.

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