Aqurium help: my tanks plants dying / anyway food to clean or reduce ammonia levels/ tips to clean t

However, since you have fish in the tank, you already have a problem. You need to do 30% water changes everyday until the ammonia level comes done. You also need to make sure your tank isn't overstocked. For guppies, I would say that you don't want more than 10-15 in a 10 gallon tank (at most). I'm pretty conservative on that number. Some people would say more are okay. You also need to get a good filter.

There are some products like "cycle" that help your tank get good bacteria in it. Some people say they work and some don't.

Aquarium maintance: Once your tank doens't have an ammonia spike, you should test your water every week for ammonia, nitrites and nitrates. You need to change enough water each week to keep these levels low (ammonia and nitrites should be at zero). When you change water, I typically change about 10%, I have a syphon to pull the water out (you can also use a new plastic bucket) and add in new water. Be sure the water has been treated for chlorine (just add a bit of declorination solution to the water before adding it, read the package). You also might want to get a gravel vacuum if you have gravel on the bottom. Add water nearly the same temperature a the tank water.

But for now, do 30% water changes daily until ammonia and nititrites go to zero. If there is algea on the glass, either use a paper towel to scrape it off or get a scraper at the aquarium store. Be sure your hands are clean (no soap, no loation) before you put them in the tank. Most guppies are pretty curious so this shouldn't scare them badly. I wouldn't use any chemical algae killer because those can be dangerous.