I like to buy my minnows by the 1/4 lb or 1/2lb. That's a lot of minnows for a small minnow bucket.
Frequent water changes will help.
Freezing water bottles and then putting them into the minnow's water helps to cool the water and allow it to hold more dissolved oxygen. This helps to also slow the minnows metabolism down so they don't need as much to eat and they don't put as much waste (ammonia) into the water.
High Ammonia levels will kill the minnows faster than anything else that I know of.
I like to keep the water temp at around 13 deg C or about 56 deg F. One frozen water bottle of 33.4 oz bottle works best. Don't fill the plastic bottle up but leave some air space at the top so that when the water freezes and expands there is room to expand. This will prevent the ice from rupturing the plastic bottle when it freezes.
That's a one liter size water bottle for you scientific types out there. :)
I keep several 1 liter sized bottles filled with water in the freezer.
I disinfect them with a 10% chlorine bleach solution after use and then wash them good before putting them straight back into the freezer.
Leave the bleach solution in contact with the plastic bottles for about 10 minutes to kill bacteria. Then wash off thoroughly and dry before putting in the freezer with any food.
I like to think that the bleach kills any germs. The minnow bucket water can get pretty gross after just a couple days when you have 6 or more dozen minnows in there. Dead minnows may have all kinds of bacteria on them after they float around in that water. So as a precaution I clean and disinfect the bottles after they are used and before I stick them back in the freezer with any other frozen food.
This system has been working for me the last two years.
This is nice because I have about 24 dozen minnows available to me at any time. I don't have to wait for the bait shop to open up to get my minnows. I can keep these minnows alive for a couple of weeks.
Another method that I have used is a small 10 gallon aquarium or even a 20 gallon aquarium. I use under gravel filters systems and power filters with activated charcoal in them on the two aquariums that I use. I treat the aquarium water with the pH 7.) buffer powder and have not use the Better Bait blue crystals in the Aquariums ... yet. I fill up a 6 gallon container with tap water and treat that water with one small cap full of pH 7.0 buffer powder. This will remove any chlorine from the tap water also. I use this 6 gallon water container to refill the aquarium when water evaporates out. I keep the aquariums at room temp or about 75 deg F. There are bacteria that live in the gravel and they take care of the ammonia and convert it to Nitrates. I change the water in the aquarium frequently to prevent the build up of Nitrates. Ammonia is converted to Nitrite and Nitrite is converted to Nitrates by the good bacteria that lives in the gravel bottom. I also use a power aerator to keep plenty of dissolved oxygen in the aquarium water.
I also correct the city water with chemicals. pH7 Buffer powder can be used if the water you use has a high or low pH. This powder will buffer the pH and correct it to pH of 7.0.
Also I use some of those blue crystals that I got from the Evansville Worm Ranch. It's called "Better Bait" Minnow Holding Formula. I got a 3lb plastic jar of this stuff. Three pounds will treat 2,400 gallons of water.
Check out their web site at
www.sure-life.com
Or call them at 830 372-2239
Regards,
Moose1am