4 rollers vs 2 apex DOS

[fishrambo]

I’m putting together a system and setting up 2 pumps with a 8ft head height and was wondering if it would be better having a 4 roller dos head or 2 and also wondering if it would stop back feed from tank to dos to drain. Thanks

 

[blaxsun]

Personally I'd go with the DOS (at least if you have any concerns with height or distance). You can always place a check valve on the DOS tubing, but I don't think it will be an issue.