Cycling tank, advice needed for dying/melting plants

2 weeks ago I got this 15 gal tank. I put in aquarium soil at the back and sand at the front. I waited a couple days before putting in plants.

After a week I put in 5 ramshorn snails.

I am doing a fish less cycle where I am putting in a small amount of flakes every other day.

Some of my plants are really struggling, others seem fine.

Things I've noticed:

• plants near the filter are more brown than the ones further away -algae is starting to form. I hope the snails eat this up -after week 1 water tested great but 2nd week ammonia has risen to 0.2. Probably just cycling and flakes (?)

I'm wondering if I've done anything wrong to kill the plants?

Also would I be best to put in some cherry shrimps or a small fish or 2 (maybe like 5 neon tetras) to do a fish cycle instead of fishless?

Tank is eventually going to be for ADFs and the front section is going to have a rock formation/cave to help them hide etc