water changes
 

i have a 30 gallon aquarium. saltwater reef

are water changes needed? i have not been doing any as I am new to the hobby and the pet store told me that they were not needed. they told me just to top up the evaporated water with fresh water and i would be fine.

my question is are:
- water changes needed in my tank?\

- what will happen if i dont do them?

-and when should i be doing them and how much each time.

Be wary of advise from your LFS. Some are great, but other not so much. Get different opinions before you decide who is "right". I would definitely recommend regular waterchanges. A good place to start would probably be 10-20% monthly.

what happens if i dont do them
\

so is adding fresh water to the evaporated water not the same?\

+1....especially if you are not running a skimmer on your tank. The corals in our tanks use various (can't think of right word...) uh, things, in our tanks that need to be replenished on a regular basis. The easiest way to do this is to do regular, frequent water changes.

Minerals!

Many things will dictate when and how much your water changes should be. Things like Skimmer, refugium, amount of live rock, bioload, feeding regiem, type of foods etc all contribute to a dirty tank. Topping up with fresh water does nothing for the quality of your water it only keeps your salinity stable. Evaporating water still leaves all the bad stuff behind. You may want to consider a new LFS as this one is leading you down a trail youll soon regret.

You need to remove water and not just top up in order to get rid of some of the pollutants in the water. You replenish the elements that your corals are using when you add new salt water. The reason you may be having problems with your corals could be high nitrates, or maybe low calcium and kH?

so how much of a water change should i do?

with a 30 gallon tank what are my typical time frames to be doing water changes. and how much..

i do have a protein skimmer....

Go about 10-15% once a week.