Krystian,
im sorry for being so harsh on your 1-gallon tank..
its not your fault, you were misled by Walmart who is only out to make a buck..
thye dont know (or care) how to properly raise fish...
an aquarium doesnt need to be super-high maintance.
just 20-30 minutes of work a week will keep it nice and clean!
If you want goldfish, you dont even need a heater!
all you need is a basic light, a good filter, and the tank..
gravel can be a THIN layer..just enough to cover the bottom of the tank..
like half an inch.
most people put gravel layers that are far too thick..there is no reason for 2-3 inches of gravel! all that does is collect more gunk, and it makes the tank *harder* to clean..
put a layer of gravel on the bottom just thick enough to cover the bottom.
lets say (just for the sake of arguement) that you have a 20 gallon aquarium.
you could have 2 goldfish,
the filter,
a light,
(no heater,)
gravel,
decorations,
a 5-gallon bucket.
and one of those siphon vaccum things..
thats all you need!
(dont even attempt live plants with goldfish..the fish will destroy the plants..and live plants are MUCH harder than just keeping fish...try live plants 2 or 3 years down the road if you want to get into that after learning more about it..)
So, you have your tank set up..
you will need to cycle it if the filter is brand new..
fishless cycling is cool, and works well:
http://www.kokosgoldfish.com/FishlessCycle.html
http://www.geocities.com/scottychaos/discuspage.htm
So, once your tank is up and running, just schedule a day once a week to do the water change, I do mine early Sunday evenings.
a few days before, fill your 5-gallon bucket with water, maybe 3/4 full..
(5 gallons of water is heavy!)
top-off the tank to re-fill it from evaporation during the week,
then drain out 2 or 3 gallons..
(anywhere from 10% to 25% of the volume of the tank)
mark a line on the back of the tank for future reference..
as you drain, you can vaccum at the same time!
take the vaccum thing, and stick it in the gravel, it will magically pick up all the gunk and fish poop and siphon it right out!
very easy..
drain the water into a bucket, or sink, or whatever..
then, take the filter media and squeeze it out in the dirty tank water that you drained out..
this removes 99% of the gunk that the filter collected during thr week, but it leaves all the beneficial bacteria behind..
the filter might still *look* dirty, it will still look brown, but you will basically clean it really well by squeezing it out in old tank water..
(dont run filter media under tap water..chorine will kill the bacteria)
If you have a basic aquarium light, algae on the tank walls shouldnt be a huge deal, because you wont have enough light to raise a lot of algae..
the fish dont need much light.
the simple floresecnt lights that come with all aquariums are perfectly fine...
thats basically it!
a few minutes of work once a week will keep an aquarium happy, clean and healthy indefinately!
live plants will increase the workload 10,000%..
dont even bother right now..trust me, its not worth it when you are just starting out..
and dont get an "undergravel filter"..they suck big-time..
they are a dying breed, and VERY dirty.
get a regular "hang on the tank" filter..much better.
like these:
http://www.elmersaquarium.com/images/112whisper_Filter.jpg
Scot