I wish to share some handy tips (just from my set-up, reading, threads at AA) I wish I knew when we started my son's tank.
When in doubt ask! Realize that what you don't know can kill your fish and ruin your enjoyment of the tank.
(#1 of all time) There are lots of knowledgeable people here willing to help. Have a plan. research and figure out what type of tank you want ( fresh, salt, planted, etc.) and what you want in it before you start. Then you can match the tank, equipment, and fish to your needs.
Get the largest tank reasonable for your budget and space. Bigger tanks are more forgiving to beginners and will keep you from running out of space too fast.
Learn about the
nitrogen cycle. It controls the tank.
Go slow with changes to your tank.
Haste = tragedy in most cases.
Remember,
good water quality = happy fish ; poor water quality = dead fish.
(#2 all time) Avoid all soap. Fish clean and people clean are totally different
Don't add things other than water conditioner to your water or tank
without good solid advice. You may do more harm than good.
Cycle your tank fish less. It is better in so many ways.
(#3 all time) Know what is going on with the water in your tank. Temperature, pH, Ammonia, Nitrite, and Nitrate should all be watched until the tank is fully established.
Test the water daily(at least when starting up) with a good kit like an API master test kit and write down the results so you can compare if a problem arises.
(#4 all time) If you do cycle with fish, (not recommended) Keep
ammonia, and nitrite below .50 ppm while cycling (they should drop to 0.0ppm when cycling completes). Keep
Nitrates below 20 - 40 ppm always. (use water changes to lower all)
Water changes are good! If your water changes are more than a 5
gal. bucket (50% of 10
gal tank)
get a Python. You won't believe the difference. You will also not dread larger water changes.
Don't over feed the fish. See water quality above.
Cycling takes weeks, not days,
be patient.
Don't rinse the filter under the tap in the sink. Chlorine will kill the good bacteria. Use warm dechlorinated water or tank water to rinse your filter.
Don't change too much filter media at a time. Good bacteria live there.
Add fish slowly. let your tank adjust.
Quarantine new fish after start up. Don't let a new sick fish contaminate the whole tank.
There are many more I am sure but these come to mind at present.