One 7 in vs two 4 in filter socks?

[BigWillStyle]

Hey! I am in the market for a sump for my fiji 76 shallow I just bought. I was going to go with my default brand of eshopps and their AF-200 but then the Fiji 30 option looked interesting with the integrated mounts. The main difference is the fiji uses 2 x 4 in socks while the eshopps uses a 7 in. I run both but I am genuinely curious if anyone has done any studies or comparisons on which is better. Does the slight increase in surface area actually justify all the extra work of swapping/washing two? Is the flow better on the single 7 that allows for less maintenance without the phosphates rising?

I run my 40 off a single 4 in, 50 on a single 4 in, 120 on two 4 in and a 150 on one 7 in. Interested in what y'all thinks is best.

 

[Timfish]

Since fish poop is an important part of the carbonate cycle on reefs I'd suggest not using any mechanical filtration and just occasionally, > yearly, siphoning out most, but not all the detritus that accumulates in the sump.

https://www.sciencedaily.com/releases/2009/01/090115164607.htm

 

[BigWillStyle]

well that would lend itself to the FIJI. One thought on that, a very active fuge would be required without any mechanical filtration. Of the two sumps the AF-200 has a much larger sump volume, especially when you consider it stays filled and is not dependent on skimmer depth