Hi guys, I been cycling my planted 20G for almost 3 weeks now, I have about 0.5-1 PPM of ammonia in my tank from day 1, and I start seeing nitrite at around 0.5-1PPM as well for almost 2 week. Nitrate level was under 5 PPM until yesterday, where it all the sudden go all the way up to 20PPM, I measure everything again today, everything still look the same. with nitrate slightly up to around 20-30 PPM.
My question is, where is all this nitrate come from all the sudden? It looks like it's going up by 10 PPM each day for the past 2 days all the sudden. If I understand correctly, 1 PPM of ammonia should convert to 1 PPM of nitrite and then to 1 PPM of nitrate. I been testing my water daily I never see any spike in ammonia or nitrite, they always stay around 0.5-1PPM. The only noticeable change in my tank the past few days is I start to see a lot of melting in my plants that were probably grown emerged, does plants release nitrate back to the water as they melt? Is it normal to see nitrate go up this fast without fish or other source of ammonia added? I never see my ammonia or nitrite drop below 0.5 PPM either.