RO does not do denitrification. Fish don't die in high nitrates. Nitrates are not desirable but it does not kill fish instantly.Do you have RO filter system at your home ?
It is better to have one of those to remove nitrates from tap water, can be a lot helpful for humans too.
Yes, 10/25/30/50% water change weekly/15 days depending on number of fish/size /filtration/aquarium size/feeding.I also like aquariums but they need timely cleaning and restoration of clean water every now and then.
I used to have one just like yours almost 20 year ago like in 2002 but later I neglected it and my parents sold the tank to somebody.
There ended my hobby of aquarist.
Zero algae in all 3 aquariums I have. I keep lights on for maybe 15-20 mins a day just to feed. I have a BCB (clay basket) and plenum system (under gravel filter with slow moving water). You can try plenum system.How do you deal with algae, in one week the tank get crazy, even though algae isnt harmfull to the fish, its just ugly , i know switching off lights can help with it but was wondering if there is any other trick