Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Try doubling your water changes and half your dosing, and pick up as many test kits as you can, NO3, PO4 and Fe would help the most.
When you give numbers, also include the units. GH is measured in several different units.
If your GH is 9 German degrees of hardness, then a lack of calcium is highly unlikely. If it is 9 ppm or 9 mg/l then a calcium deficiency is very likely.
Test right before a water change, then shortly after. Wait for the new water to get well blended, but before you dose any fertilizer. Maybe an hour or two after a water change.