Ammonia high

Hi.. I have 10mnths old fowlr tank.. I just installed vertex protein skimmer about 2 wks ago.. But after installing protein skimmer my ammonia nd nitrate spike up nd killed my invertebrates.. I always do 10 gallon water change every week.. Rt nw levels r
Ammonia 0.50
Nitrate 5.00
Ph 8.2
Nitrite 0
Salinity 1.026