Black film on spiderwood

[FinnedFriendBeginner]

1 week old tank. Spiderwood in the tank started getting a white film around Day 2 and turned to black film now. The film comes off if scraped with a brush.

 

Are these algae or just bio film? Should I be concerned?

 

[Tony s]

You actually have 2 things going on simultaneously. First, you have brown algae on everything. Which is completely normal for a brand new tank. It feeds on silica in the water. Almost every new tank gets it. Now the brown sludge on the spider wood is also completely normal. It’s a bacterial bloom from the wood. The bacteria are just eating the last little bit of edible material still on the wood itself. It would look like a whitish slime except it’s brown due to the brown algae. 
 

cures- brown algae is caused by diatoms in your water. Their shell are made from silicates. When there’s no more silicates, there’s no more algae. Surface feeders like snails, otocinlus, or even very small plecos (depending on tank size and species) will eat it and help remove it tons faster.

biofilm on spider wood- yeah, I freaked out about this too. The first time I saw it. Not a big deal. It goes away after it consumes whatever it’s eating is gone. If you scrape it off before that, it just comes back. Maybe a week or two.

both of these are common to new tanks and new wood. Neither of them is harmful to your fish in any way 

[MattyM]

Boiling the wood will help remove the film - just make sure to use a pot you don't really care about. I have a cheapo enamel pot for this. The film may still come back but less so, and shrimp/snails eat it right up.