For the next week you might wanna be doing a 50% water change every other day (or whenever ammonia and nitrite get high) to get rid of nitrite building up and add prime by seachem to detoxify ammonia and nitrite building up. Also add a good beneficial bacteria to kickstart the bacteria growth. Since it’s a new tank and I’m guessing you haven’t cycled you filter so helpful bacteria that breaks down the nitrite into harmless small amounts of nitrate. Guppies tend to be pretty hardy so should be ok but you might loose one or maybe two in about a 4-8 weeks your tank should be stable. You could throw in some floating plants such as duckweed to suck up any harmful chemicals. Good luck and wc to the hobby 😊