Large nitrite spike shrimp only tank

[Willbacon23]

Hey guys, I have 4 shrimp in my 20 gallon shrimp tank which before putting them in my tank had been cycling for around a week and a half with a HOB filter and a sponge filter in the tank as well as having moss balls and java moss and substrate from an established tank. Today I saw a huge spike on nitrites from 0 to around 1.5ppm, with nitrates and ammonia still both around trace. I’ve instinctively done a 50% water change but I’m shocked how this had happened, I’ve only fed them so far a quarter of an algae wafer. Any help/ advice would be greatly appreciated

 

[seangee]

Daily water changes and / or reduce feeding. Sounds like your tank is only half cycled.
I once did an experiment on a brand new uncycled 15G tank and dropped a single algae wafer into it. No fish, no plants and just the brand new filter running. Within 24 hours the ammonia reading was off the chart - the API test goes up to 8ppm.

Today that tank has over 200 shrimp, 30 fish (CPD) and an unknown number of Malaysian trumpet snails. When I feed algae wafers they get one single wafer between them. For 4 shrimps a tiny sliver is enough.

 

[Willbacon23]

Daily water changes and / or reduce feeding. Sounds like your tank is only half cycled.
I once did an experiment on a brand new uncycled 15G tank and dropped a single algae wafer into it. No fish, no plants and just the brand new filter running. Within 24 hours the ammonia reading was off the chart - the API test goes up to 8ppm.

Today that tank has over 200 shrimp, 30 fish (CPD) and an unknown number of Malaysian trumpet snails. When I feed algae wafers they get one single wafer between them. For 4 shrimps a tiny sliver is enough.

Perfect thank you! Yes itsnrly annoying, I was debating doing gravel vacuums but I feel thatsnnot that important likely. Just going to keep doing water changes and maybe feed a slither every 3 days?