DIY sump filter questions

[Coyne]

Im just kind of toying around with an idea of setting up a 40 gallon breeder and converting a 20 gallon tank into a sump filtration system.
This may or may not happen, and if it does happen it wont be for a while.

Just for fun, I was plugging my fish stocking into AqAdvisor and realized that I had no idea what to put down for filtration. How does one figure out what the filtration capacity is for a DIY sump filter? Is it more or less based on the gph of the return pump, or does the water volume factor in as well.

Another question: When considering fish stocking, do I use the combined volume of the main tank and the sump, or just the main tank? Im thinking about the number of fish, not the size of the fish.

 

[Retired_AF]

Not sure how to calculate the filration numbers, but to answer your question about the stocking, you should use the volume of the tank you are puttting the fish in. The recommended tank size has a lot to do with the physical dimensions of the tank as well as the volume of water. For example, some fish need a tank that is a minimum of 6 feet long due to its activity level as well as it's physical size when fully grown. Thus a 40B would be inadequate since it is only 4 feet long and the fish can't swim in your sump. The sump is there for 2 reasons: 1. To increase your water volume. and 2. For filtration. It is also a good place to install the equipment you want out of sight such as heaters, skimmers, etc.

Looking forward to seeing pics of your setup!

 

[Coyne]

The fish I'm considering are all small community fish that are currently homed in two separate, lightly to moderately stocked 20 gallons (long), so a 40 gallon breeder would be an upgrade as far as footprint is concerned. Swimming/activity space would be significantly increased and is not my primary concern.

I was wondering more about my ability to increase the number of fish in some of the schooling species. Its in that regard that Im wondering about which water volume to take into consideration.

An understanding how much filtration capacity I'll have is probably what I really need.