water changes...how often

BTW, there is no such thing as pH shock. Fish cannot read pH. There is however such a thing as osmotic shock, from using water with too great a difference in TDS (total dissolved solids) from the existing water.

When someone starts telling you that pH kills fish directly, that is an excellent hint that they are not as knowledgeable as they claim and are prone to repeating aquarium myths which they have not studied for themselves, and that they do not understand water chemistry and fish physiology very well.
 
Test strips: Not so good? I have Mardel test strips and there is nothing that says "ammonia", and the pH is wrong wrong wrong. It says I have low pH, around six, when my special pH test says 7+. I find this disturbing.

Strip also says nitrate is going up. Something to worry about?

Can anyone suggest a good test kit?
 
AquariaCentral.com