It might be over feeding ( but i dont know, i dont think its that but what else can it be ? )
Thanks fry_lover for the helpful advise !
Could easily be over feeding, that'll do it. Not exlusively, but over feeding is a common culprit
I now use JBL Nitrite test kit which shows up Nitrite from as low as 0.05 mg/l when a lot of other kits, the first reading on the chart is 0.25mg/l, so i can usually see if one of my tanks has even a TINY bit nitrite (i.e. some low level recorded). I test all the time, not becuase i am worried, but because i just like testing at least twice per week (sad i know LOL). But also i learn from it as well, i mean, in my Malawi tank last week (because i have some fry in there - which isnt a good excuse for what i done) but i fed a bit too much, i put pellets in water to soak for a bit then added to tank so they "broke down" easier for the fry, but there was particles EVERYWHERE and i thought "too much food". Next day the Nitrite reading was in-between 0.05 and 0.1 mg/l as opposed to usual 0.0
It was only 0.05 to 0.1 because this tank has x2 mature Eheim 2028 externals, and i am also currently "cycling" a Fluval 4+ internal in there, that is probably 50% mature now. if i had put that food into a tank without such filtration, i am sure the Nitrite reading would have been 0.25mg or even more. I over fed basically. And because it all was tiny particles i couldn't exactly put the net in and fish out the excess food!!!
If you were really religious with your nitrite and nitrate testing you will often see a direct corelation between amount of food going into tank and nitrite and nitrate levels (if over feeding, i.e. the amount of over feeding would have a good relation to the reading scores), this can also be true of the snail population in tank, not always, but sometimes, i.e. more snails if over feeding and often snails getting out of control is sometimes (not always) directly due to over-feeding.
People might say test kits are unreliable, but my JBL nitrite seems good in that if i ever over feed or i have a filter problem (not too long ago a plug come out on my of filters in another tank over night) the JBL Nitrite kit will detect even the slightest rise in Nitrite, these tiny nitrite readings can often give you a good "heads up" in terms of whats happening in your tank (feeding wise and the state of the biological filtration)
