Sump design critique

[Myka]

What is the purpose of your refugium? How are you going to fill the ATO when it's behind the skimmer?

[gregzz4]

Are you planning on using filter socks ?
If so, they would be best put before the skimmer and have a chamber of their own

Look at some Concept builds for ideas ...

And ya, having your ATO in the sump is a waste of realestate and hard to get at. Especially when you have to clean out the mulm that will eventually build up when bacteria grows in there

Keep it separate and accessible