Pictures will be coming.
For starters this is what were running as for tanks.
3 225 gallon tanks joined together by 3 inch PVC pipe creating gravity feed to a separate smaller tank (lets say 5 gallon)with a sand and gravel medium fed through the bottom of the tank by means of a perforated pipe inside the tank. Then we use a low pressure pump with high volume output(1/3hp 2000gph)to sifen off the top of the 5 gallon tank and pour into the first 175 (thats aprox how much water we put in the tanks) gallon tank creating a continuous loop that includes aeration of the water .
With this system we can go 3 months with out changing the water and 2/3 weak intervals cleaning the sand gravel medium.
No special filters needed, though we are planning to ad an Ultra Violet light to aid in water purification down the line(spendy). We also have the tanks in a well insulated shed to control the temp. The cooler the water the better, less defecation and less need for feeding.
This got us through the winter for bait for ice fishing never having to buy crappie minnows or fat heads. Just a few days of strategic placing of minnow traps in the fall and a few times chopping through the ice.
Confusing picture in the mind? I understand! Ounce I get the pictures up further explanation will be easier to picture.
I can explain the filtration. Simply put bait fish extrude ammonia and nitrites through the gills and poop and that ammonia needs to be eliminated from the water. The sand,gravel(gravel meaning pea rock) gives an area for good bacteria to thrive that breaks down ammonia consecrates. To create this good bacteria in your system. It may take 3 to 5 days to get a healthy colony imbedded.
I have seen car wash sponges or a mixture of gravel and lava rock for a medium for bacteria to live. Point is a porous structure is needed for good bacteria to collect.
There are other filtration media like charcoal that were looking into but for now this system is getting us by pretty good.
Easy way is to go to a bait shop or where ever they sell those aquarium fish collect some of their water and an old filter(filter must still be wet for the bacteria to live)and add it to your system and after a bit of time your system will have its own beneficial colony of bacterium.
More to come, stay tuned if interested.