Existing tenants paying way below the market rate. What to do?

[Tarun Mitra]

I have just bought a new duplex. I have existing long term tenants living in each unit. One tenant is living there for 10 years paying around 1080 and another is living there for 4 years and paying 1265. The current median and average rent is above 1650 according to rentometer and zillow. I bought the property thinking I will be able to increase the rent and bring it to the market rate. But if I increase the rent for tenant_1 to even 1400 it is like 30% increase. I definitely want to bring the rent up to 1550 at least and then gradually increase it to the market rate. I am not sure how to go about this rent increase. I just started being a landlord and this is my first property. Can you guys suggest how should I increase the rent here? Today is my day 1 of owning this property.