"Cotton pads" on LR

[Saltedpals]

Currently have about 13 kg of LRs in my tank. Into cycling process for about 3 weeks plus now. Notice some white “cotton pads” (about 3 cm in diameter) on parts of the LR - especially located at the underside of the LR. After a few days, these white “cotton pads” turn brown. I tried scrapping a bit but not really coming off. Should I be alarm? What are they any way?

[junyong84]

coraline alage decomposing

if ur tank is still undergoin cycling....its probably part of e cycling process

if ur tank is old..there muz be sth wrong wif ur water conditions... calcium levels...etc...