How To Clean The Tank
Let gravity do the work - siphon it! In a tank of up to 5 gallons in size, you can use a piece of airline tubing. Insert it into the water and fill it completely with water, and put your finger over one end. Now bring it above the water and over the bucket which is below the water level - this way you can vacuum debris from the bottom. Once you have the bottom cleaned, start removing water with a jug. You can also use a turkey baster to clean the bottom of fish bowls.
In larger tanks, you could acquire a gravel vacuum from a store, and follow the same steps, until you have taken out all the water you want to remove. With many or large tanks, one can invest in a Python, manufactured to connect to a water tap so that you do not have to move heavy buckets of water. It vacuums the tank and has an water out/in lever connection at the tap. Water should be conditioned and made the proper temperature before addition to the tanks.
Water Change Schedule
It is possible for fish to live without water changes for sometime, however, this is setting them up for possible disease outbreaks, such as fin rot and columnaris. Keeping the water as clean as possible will keep your fish as healthy as possible. Raising fry entails more water changes than normal due to frequent feedings. Water changes themselves will help fry to reach their best potential size as well.
Fry: 20 - 25% every 3 days, or 50% once or twice a week
Adults: 20 - 30% once a week.
The schedule you choose will depend on these factors:
Inches per fish per gallon (the ideal maximum is one inch of fish per gallon for a normal, long tank).
Breeding goals (if showing or looking for greatest size, this would entail more frequent water changes).
Time available (this would mean less frequent, larger changes).
If your tank has more fish than the ideal maximum, change water at the higher amounts. Water changes are less important if the tank is under stocked.
Changing water becomes a simple exercise once you set up a routine and schedule and understand how to keep it as stress-free as possible for your fish. The more often you clean your tank, the better accustomed your fish will be to having your hand in their tank!
Conditioning the Water
Make sure the water you replace is safe for the fish. It should be the same temperature and pH. If you use salt in your tank then you should add it first in the new water at the rate you use per gallon. Salt does not evaporate so it is not added to the amount of water you "top up". Use a water conditioner to remove chloramines and chlorine if you are not sure if there are chloramines present. If you simply have chlorine to worry about, you can simply leave the water out overnight and it will evaporate. In fact, if you change only 1/4 of the water, you do not really need to remove the chlorine since the amount in the tank will pose no threat to the fish, and it disappears after a day. There should be no need to add a conditioner that stimulates slime coat.
It is usually best simply to use a conditioner that is basic and simply removes or neutralizes chlorine and chloramines. It is not a good idea to add more chemicals to a fish tank than is necessary. Adjusting pH is usually a losing battle as well, and if you are tempted to try, think again, because eventually disaster strikes and pH swings cause stress and possible death. If your water's pH is lower than 7.0, it is better keeping soft-water fish such as Angels and Characins.
Eventually you will acquire an understanding of your water and what you need to do to change water with the least stress on the fish.
There is no need to remove algae except from the front and sides of the tank for viewing purposes. However the corners of the tank should not be allowed to get too dirty. Occasionally the bottom and entire glass surface should be wiped down prior to a water change. Tetras, guppies and other small fish have small stomachs so they eat small amounts throughout the day, and algae provides a between-feeding snack.
If algae becomes a problem, find the reason for algae and control it. It is better than having a pleco or an algae eater. Algae thrives where there is too much nitrate or phosphate in the water, and when there is too much light (often light from a window is the culprit). Where the problem of nitrates exist but there is low lighting, brown algae will accumulate. If water changes do not help you can assume that phosphates are being added through fish food (some contain high levels of this nutrient), cheap brands of carbon, or your tap water (in this case, use a phosphate sponge).
Inside box filters should be changed when the filter floss gets brownish throughout. Change the dirtiest floss and save about 1/3 of it to replace between the layers of new floss to help seed the new material and retain some of the "good" bacteria.
Every once in a while, the filter may need to be completely cleaned when it gets filthy. The easiest way is soaking it in diluted bleach until clean, then rinse until no chlorine scent is present. Meanwhile, set a new filter in the tank with some of the used filter media in it.
Power filters should be rinsed once a week. Inserts should be rinsed in tank water or dechlorinated water so that the "good" bacteria is not destroyed. Power filters such as the AquaClear should be removed and thoroughly cleaned once a month. The motor will get gummed up and if the power goes off, it will not re-start itself. This can cause major problems if you are away at the time.
Rock salt is an excellent and safe-fish remedy for various problems when avoiding chemicals, and a good general additive to relieve stress and protect against ich. It also prevents nitrite poisoning (brown blood disease) in fish. However, salt in fish tanks is not mandatory and is not advisable if you have a community tank with anything other than other salt-hardy fish.
When adding salt as a regular additive to the tank, top up the tank before/between water changes with unsalted water. The reason for this is that salt does not evaporate and eventually a build-up of salt will accumulate in tanks that are not regularly topped up with plain water. Then, add the ratio of salt to the water you have physically removed from the tank. For instance, if you have removed 5 gallons and the tank is kept at 1 tablespoon per 5 gallons, dissolve one tablespoon of salt in the water before adding to the tank.
It is a myth that table salt is toxic to fish. The iodide can be helpful and the anti-clumping agents are minute and fish-safe, though it sometimes clouds the water slightly. However, avoid salt that contains such items as dextrose.
Other safe alternatives to expensive aquarium salt include sea salt, rock (cooking) salt, and solar salt. Salt, when added to fish tanks, is usually in the amount of 1 tablespoon per 5 gallons, or 1 teaspoon per gallon.