GH & KH dropped

[Andrew_GB]

I have just checked my water and noticed the GH and KH have dropped considerably since last testing. I have added carbon since last testing, has this caused the drop, and are the new levels acceptable?

GH: 6
KH: 7

These are on the German scale.

Also my pH has dropped from around 7.8 to 7.4.

 

[wildroseofky]

Do you use CO2? It will cause the drop in all those things. The numbers look fine for now but you might want to add some limestone, seashells, crushed coral or something like that to buffer it. I have been using limestone and seashells. It has kept my GH and KH and PH stable for several months.

 

[Rivercats]

How often are you doing WC's and how much do you change out each time? Part of the reason for doing a large weekly WC is not only to remove excess nutrients but to add buffer back to the tank water (unless you have soft tap water which is quite uncommon). Right now your numbers are very good. I run my tank Gh and Kh at 4 which is good for plants. If your doing large weekly WC's and your readings continue to drop then adding crushed coral to your filter or hanging some in a media bag under the outflow of the filter is a good idea.