Newbie - Overflow tips and size for 45g pf-300 vs 800?

[NancyFish]

Hello, so I just set up my 45g (36x12x24) and want to do an overflow.

I found the eshopps and the 300 is rated for tanks upto 75g but the blog on the site recommends 10x my volume.. so that’s 450 without sump included..

Think I’m better off with the 800 or 300 is plenty? I’m assuming I’d just run a higher flow rate, but I don’t want additional risk to overflow. Recommendations on return pump, or other tips? Tank will slowly have some small fish and eventually some soft coral.

 

[RocketEngineer]

For a HOB overflow like that, bigger isn’t better. You want enough flow through the U-tube to push any bubble out to ensure it keeps working properly.

The 10X turn over is just a number, it doesn’t have any meaning. What you’re aiming for is to ensure the water in the sump has the same basic parameters as what is in the display. That way any changes are seen in both locations and the equipment can respond accordingly. I’ve seen big systems go down to below 3X but that’s my personal lower limit. At 4X you are flowing the entire volume of the display through the sump every 15 minutes. That’s plenty for most of our systems.