Will APT raise GH or KH?Updated 2 months ago

No.

The Calcium and Magnesium levels in APT fertilizers are too low to affect your tank's GH levels.

For example, APT provides ~1.6ppm of magnesium over the course of a week. In comparison, 1dGH is around 17ppm calcium/magnesium ions.

So you would need to overdose APT by 10X to raise GH by 1dGH. 

APT does not affect KH as it does not contain carbonates.