0.25 nitrite
again today, so another water change undertaken.
Potential explanations [and likelihood of it accounting for the problem]:
* tropical mix frozen food fed on Mon: to get rid of any nasties, I rinse it beforehand with half a kettle of boiling water followed by thorough rinsing in cold water, and there was less food than usual as I’d inadvertently used the larger net during rinsing and lost a lot through that; [unlikely];
* limnophila sessiliflora had been very thick and long: although I separate the strands most days to release any fish food caught in it and rotate the strands a couple of times a week to remove/reduce algae (usually brown although looks more black on removal), I had a bit of a poke 7-10 days ago near the base with the aquascaping tweezers to remove any clogging the roots, and unfortunately caused most of the stems to break – they seemed weak and almost melting, held together by the brown algae; I left the long green but root-less stems in tank as floating plants, removing only those that looked dead; [possible];
* JBL Atvitol started daily on Mon as fish food been open for a while and to keep it vitamin-rich (had been using it intermittently prior to that); [unlikely - doubt the product would sell if it affected water quality;]
* as per photo, I’ve been tucking extra filter media into each of the slots by the filter intakes, more-or-less from the start of getting this filter over two years ago; recently, though, I’d put portions of thick/coarse phosphate pads in there. Although this had never been a problem with the filter sponge/wool, I wonder if the thick phosphate pads were impairing the flow of water and causing beneficial bacteria in filter to die but NB it wasn’t impairing filter outflow – cf https:///www.youtube.com/watch?v=gO9gWa_G8L0. [most plausible explanation so far, and
@jaypeecee may have a view on this given that he has had this brand/model of filter before].
Views welcome, including if anything from my previous comments may suggest anything.
For definite, I haven’t forgotten to add Seachem Prime – very particular about keeping alert during water changes and ensuring that it’s added.