As you don't have a heavily planted tank you could use Root Tabs which are a plant fertilizer - they come in the form of small tablets. These will give new plants stronger roots and keep plants lush and green. They will provide the key nutrients, such as iron and potassium, required for vibrant growth. You set each tab into the substrate to deliver the nutrients right to the plant's roots. Each tab slowly releases nutrients and lasts up to one month. you use one tab for every 30 square inches (194 sq cm) of surface and push midway into gravel bed.
Or if you prefer you can use liquid ferts which you add weekly into your water change bucket when you do your weekly vac and water change - dosage will depend on how many gallons you have.
Both are easily obtained from your local fish shop or on Ebay and neither will upset the water chemistry.
With regard to the foods frozen would be easiest. Rams like any 'meaty' foods - mosquito larvae, bloodworm,glass worms, shrimp brine, tubifex worms etc . I fish my mosquito larvae live out of my pond along with any bugs that have fallen in there. They were also very partial to cooked mussels and prawns . I defrosted one every so often and shred them very small.