Calcium, dKH and mag help

[Myka]

I'd recommend the Tailored Aquatics line. It's liquid and easy to dose a capful or two. On a big tank or high demand tank it's expensive, but a low demand tank your size is the perfect customer.

Magnesium I would buy in dry form though since you use a ton of it to boost Mg even a little. Put it into your water change water to boost it up a but rather than dosing the tank directly. Once Mg is at a good level and the new saltwater is at an appropriate level (many salt mixes are low) then it's easy to maintain -it won't get used up fast.