I think four 7" socks would handle your flow without a problem. Fitting them in a 75 shouldn't be too much trouble, especially if it doesn't have a glass brace. You are 100% correct that more socks = longer interval between changes.
Overall great thread and it would have really helped me last week in deciding mesh or felt. polyester vs polypropylene and other aspects of the socks but I'm not quite sure if this is right but you stated that a 7" bag has over triple the surface area of a 4" bag with the same length.
Earlier i did some math because i was deciding on having 4, 4" bags or 2, 7" bags of the same length.
If the solution for finding the surface area of a bag is 2(π)r x L + πr^2
If this is the right solution for finding the surface area then a 4"x16"long bag would have a surface area of ~251in and an 8"x16"long bag is ~603in
That means the bag double in Diameter would have ~2.4x the surface area
However if the bag is tapered at the bottom then the solution just would be 2πr x 16"
In this case 2 4"x16" long bags would have the same surface area as 1 8"x16"long bag
P.S. I've never seen a filter sock yet so I guess i shouldn't be talking. But these are the numbers I came up with to help me decide on 4" or 7" socks. Also this is not to an attempt to attack you and my math may be wrong.
Overall great thread and it would have really helped me last week in deciding mesh or felt. polyester vs polypropylene and other aspects of the socks but I'm not quite sure if this is right but you stated that a 7" bag has over triple the surface area of a 4" bag with the same length.
Earlier i did some math because i was deciding on having 4, 4" bags or 2, 7" bags of the same length.
If the solution for finding the surface area of a bag is 2(π)r x L + πr^2
If this is the right solution for finding the surface area then a 4"x16"long bag would have a surface area of ~251in and an 8"x16"long bag is ~603in
That means the bag double in Diameter would have ~2.4x the surface area
However if the bag is tapered at the bottom then the solution just would be 2πr x 16"
In this case 2 4"x16" long bags would have the same surface area as 1 8"x16"long bag
P.S. I've never seen a filter sock yet so I guess i shouldn't be talking. But these are the numbers I came up with to help me decide on 4" or 7" socks. Also this is not to an attempt to attack you and my math may be wrong.
Thanks for noticing, you are absolutely correct. My math needed some help there. I was pretty tired when I did the math and used pi times radius squared to figure circumference...
So you are right that a 7" bag would have just under twice the surface area of a 4" bag.
A 7" diameter circle has just over triple the area of a 4" circle, but that doesn't have anything to do with filter socks!
I am sure there are plenty more possibilities out there. Has anyone used any of these products or other manufactured sock holders? I am curious how easy they are to switch out, whether they use standard sized socks, et cetera.
I'm planning on using the BRS holders and one really nice thing about them is they come with both adapters so you can use either 4" or 7" socks. Pretty cool if you find that 4" socks won't work for your setup. Just pop the 7" adapter into the holder and change the socks and keep the same holder.