(A guide to fresh water Aquarium keeping - Gordon Rodricks)
Only once a week do the following:
a) Siphon of into a bucket about 1/3rd of the water by running a 3/4" plastic tube over the bottom of the tank, about 4mm from the bottom. Disturb the sand with the plastic tube as the suction is in progress so as to allow the sediment and dirt get siphoned off. Move the tube in between plants & reeds whilst suction is in progress.
b) With a blade or plastic scrubber scrape the insides of the glass gently to remove any brown or green algae growth from the glass. Clean the outside glass with a damp cloth.
c) Change the diffuser stones every week. For this you should have 2-3 diffuser stones as standby.
d) Top up the water siphoned off with 2-3 days old water.
e) This is all the maintenance you will need and this takes about 1/2 hour a week.
DO NOT CHANGE WATER FREQUENTLY THAN INSTRUCTED, SINCE IT IS BAD FOR FISH TO CHANGE WATER TOO OFTEN.
IF YOU FOLLOW THE ABOVE CLOSELY YOUR AQUARIUM WILL GIVE YOU MANY HOURS OF PLEASURE.