K and Mg def IMO- good luck
Dude what country do you live in?i went to the only pet shop and they said that they could order me one in but it would cost£15 and take a while to be delivered. Will definitely be able to get the mollasses tomorrow for a pound or two and will investigate more places for a ph testing kit.
Stateside, the aquarium kit runs $5 or less. Works great!
Household remedies for pH control such as vinegar, lemon juice, baking soda should be left for emergencies as they only last about as long as it takes to go to the store for legitimate pH Up or Down.