fish dying/setting up correctly?

Question
Hello, Chris I have had my 1st tank ever set up for two weeks now.  We rinsed everything well before putting the water in.  We are using a 20i filter recommended to us by the people at a pet store.  The tank has been used before and was given to us.  It measures 30"x18"x29" and is a 27 gallon tank.  Our pump is good for tanks up to 125 gal.  We have (had) two mollies, (one of which passed away today after giving birth to 7)an algae eater, and 6 platties.  Before adding fish we did treat the water with water softener and stress coats as well as special salt.  The tank was running for three days and during this time we noticed that the water became a bit cloudy so we took a sample to get tested and were told it was okay and to add a clarifier solution.  We did not add fish until the third day.  My mollie, which we thought at first was dead because it was doing headstands and letting all the bubbles move her around the airstone or decoration, turned out to give birth, then later died.  A platty also began acting the same way and eventually died also.  The water is a bit cloudy still and these two fish were not floating but at the bottom of the tank.  what could be wrong?  It hasn't even been a week.  Another question, when we change the water do we have to first put water in some container and add the treatments, waith three days, then switch out the water?  Or do we just remove 1/2 of the water and pour more in and add the solutions and salt?  thank you for your help.

Answer
Hi First Timer;

When making water changes you should only replace 25% at a time. Get a new plastic bucket from a hardware store to use for changes. I like the 5 -gallon size with a heavy duty handle. The good ones don't bend or warp when you pick it up full of water. Even a new bucket should be rinsed out well before using. Use a water conditioner (for removal of chlorine, chloramine, metals and stress) in the bucket of fresh water before you add it to the tank. You can add the salt to the water bucket too. Water conditioner works instantly so you can gently pour the water in the tank right away. Make sure the new water is the same temperature as the tank water before you actually pour it in the tank. You can add a little hot or cold tap water to get it adjusted. The water conditioner already in the bucket will remove the bad stuff from additional 'temperature adjustment water' too.

Sometimes fish will die after being moved. Female mollies and platies can die giving birth too. Especially when under the stress of being moved to a new home. New tanks can be very stressful for fish at first. Cloudiness is a normal part of the process. It will come and go. Here is a link to my article about new tanks that will help you know what to expect in the first few weeks;

http://www.xanga.com/Expert_Fish_Help

Here also are some sites that may interest you as a beginner;

http://www.firsttankguide.net/
http://www.fishprofiles.com
http://www.fishinthe.net
http://fins.actwin.com/mirror/begin.html
http://freshaquarium.about.com/od/aquariumstartup/Aquarium_Startup.htm

Have fun and let me know if you need more help...

At Your Service;
Chris Robbins