I think so, because it's bigger than the other one... Also, today I found that she/he released the shell.
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Unfortunately today I had 0,25 nitrite. Probably due to skimmer working improperly. (video below) I suppose its because I've added 5ml of Seachem Prime(my tank is 130liters), that according to reviews may alter skimmer performance.
Or maybe my new 11liter external filter that arrived yesterday was an issue, as live rock inside may have absorbed some waste particles from the water and they decayed inside.
Also, as I have purchased a new live rock - I fragmented it into parts to put inside, occasionally some living things like worms may have died causing contamination. (doesn't answer the improperly working skimmer problem)
Another reason probably is that yesterday I was also cleaning my skimmer (reassembled it and took out waste from rotor), but I don't think that's the case.
So, nothing changed except:
new filter with live rock
5ml of Prime
reassembly of skimmer.
As for now the skimmer is still working the same way... I'am really worried about my inhabitants
Maybe anyone has a clue what's going on ?
P.S
Did 15% water change today to address the Seachem Prime issue. However, if it is the root of a problem, 15% probably is not enough.
Removed some small fractions of live rock from the filter to prevent organics accumulate there.
Added DVH BioGro