Multiple SLAMs with in 13 days. What am I doing wrong?

[joshlarsen]

I opened my filters this morning to look in their again and at the top I found some black crud again. Is that some kind of algae or is it just oils or something? I ended up using Dawn dish soap and a brush to get it off and then put bleach in rinsing after each and got it cleaned out.

 

[Mdragger88]

I opened my filters this morning to look in their again and at the top I found some black crud again. Is that some kind of algae or is it just oils or something? I ended up using Dawn dish soap and a brush to get it off and then put bleach in rinsing after each and got it cleaned out.

View attachment 448063

Likely oils & such from sunscreen etc.