why why why

[hanks]

Some times the test kits are not accurate. They do go bad after a while. You could also have your LFS check your water.

 

[Jesse]

the kh is
3dkh or 53.7ppm kh

That's the problem, your KH is low, which means your water has very little buffering capacity, despite its neutral pH. Therefore, fish waste and organic matter can have a profound and immediate effect on it. I would recommend adding a bag of crushed coral to your sump or mixing it in your substrate. Your KH should be in the 100-200 ppm (mg/l) or 6-12 degrees hardness range. See the article below for details regarding KH ranges:

http://www.thetropicaltank.co.uk/hardness.htm

I have the same problem with my water, except it's slightly alkaline, pH 7.6, with KH in the 50 to 100 ppm range. I have crushed coral in all of my tanks.

 

[DiXoN]

i am going to get the water tested by a lfs also but it looks like i am sorted.
i need crushed coral i can stick it in one of my filter baskets