Everybody has problems with keeping the fish tank clean.
there are few techniques which I will go through with you today to hopefully help with cleaning out your tank, all of which will need a bit hard work.
There are many things you can buy to help you with clearing the tank, I have never really ventured in buying items, I try to go for more old fashioned ways to clean the tank some which will require hard work, there is no easy way to clean your tank.
One thing I do recommend is buying a sucker fish or by its real name Hypostomus plecostomus, they control the algae which forms in the tank.
These are very good at cleaning the tank however depending on the size of the tank they will only reduce so much similarly to you have a constant supply of food, you can only eat so much.
You should clean the filter every couple of weeks, this is the main cause of the tank becoming dirty, a little dirt is good for the environment for fish to live in but too much can clog the filter and eventually stop it from working.
The stones become very dirty and require a good clean, to do this I suggest a small piece of hose pipe to suck out the stones or dirt. Fill the hose pipe with water and cover over with your thumbs place one end in the tank under the water, and the other in a bucket, remove your thumbs and water should start to fill the bucket use the hose pipe as a vacuum cleaner and suck out all the dirt & stones, you may want to use a sieve to keep the stones and give them a good wash. This is a great way to clear the tank but be careful not to take out too much water as you will need to replace it at some time I suggest doing this when you are going to do your water change.
The best way I can suggest to clean the glass which my uncle shown me is to get a Stanley knife blade, and take off all the algae from the tank by using the blade end and sliding it down the glass. This is a very quick and effective way of cleaning you fish tank quickly and make a big difference, don't worry it will not damage/scratch the glass.
Whichever method you decide remember to put towels down not to spill your water everywhere.
Once it is clean it easier to maintain your tank if it is already clean but if your like me you tend to do every couple of months and do a full clean from top to bottom.