cloudy tank-new pump

Question
QUESTION: We have a 63 gallon tank, have had it for a few years now..we recently bought a new pump cause ours wasnt working correctly..Everything was all good, made 50% water change a week ago, and water is still cloudy..At first when the change was made (water) it was clear..Now its like the pump isnt working..We dont over feed our fish..
Do you have any thoughts or ideas on what to do?
When I ask Petsmart they really dont know..

Thank you for your time and help,
Jenni

ANSWER: Hi Jenni,
It sounds like your tank crashed.  Because you removed the old pump, it took out the majority of the beneficial bacteria that breaks down ammonia.  The new pump doesnt have the necessary bacteria yet, so your tank cannot handle the fish's bioload.  Basically in summary, I believe you have a bacteria bloom.  It should clear itself within 2 weeks, maybe less, maybe more.  During this time, I suggest you do more frequent water changes to lower toxin levels.
-Matt-

---------- FOLLOW-UP ----------

QUESTION: Matt~
Thank you very much for your help. I used a test strip to test the waters and this is what it says: Cholorine: safe
KH(alkalinity):low, hard Water and Nitrate: safe

Thank you,
Jenni
IS there any specifics I should add to the water?
What about stress enzyme, it puts the bacteria in/back?


Answer
Hi agian Jenni,
I usually avoid all medications all together.  Less medications and products in the tank makes the tank more stable.  I dont use any medications in my main tank whatsoever.  If I decide to treat a fish, I move him to a seperate hospital tank and treat him individually.  Try to get used to doing liquid testing.  Strips are very very inaccurate.  When you get liquid testing, keep the ammonia and nitrite as close to 0ppm as possible but never above 1ppm.  For nitrate, try to keep it below 20ppm and never above 40ppm the lower the better.  

Stress zyme supposably "reduces" stress, it doesnt add bacteria.  There are no products that put the bacteria back in the tank.  Even the small bottles that contain "live bacteria".  How can it be live if it is dry?  It is false advertisement along with many other things such as the driftwood made out of grape vines that rots in a week and some aquatic plants that are not true aquatic and die sumberged.  

To introduce bacteria in a tank, you need to remove an item from a healthy, disease-free, established aquarium and place it in yours.  Items such as filter media sponge/poly fiber, gravel, decorations, etc.  It is called "seeding".  A used filter material is saturated in beneficial bacteria and is the best item to use.  You can ask a friend for it or a local fish store.

Let me know if you have any further questions or if you need me to explain something further.
-Matt-