How I Keep Daphnia All Winter Long
by Norm Ruebsamen
I have had the same daphnia culture non-stop for the past 4 years. I have enough to feed 40 tanks full of fish once a week. If anyone is interested, here is the set up.
I have three 30 gallon plastic tubs on a table in the basement. A 48" shop light hangs just above the tubs containing two 40 watt fluorescent bulbs. The tubs were filled with water, (we have well water) a starter culture of daphnia , and a good supply of ramshorn or pond snails. I have a cheap air pump with tubing running into each tub for aeration. Don't use an air stone, you want large bubbles. I feed the daphnia daily. To make a weeks supply of daphnia food I blend 1 tsp.. (or 3 tablets) of brewers yeast with about 25 frozen peas, several spinach leaves, a tablespoon of sweet potato baby food and 1 quart of water. Blend until liquefied. I keep this refrigerated and feed 1/8th to 1/4th cup to each 30 gallon daphnia tub per day, depending on the amount of daphnia in the tubs.
Once a week I siphon off daphnia along with 1/2 of the volume of water in each tub. I siphon through a baby brine shrimp net, reserving the daphnia and tossing the water. I replace the water with well water. Once every 3 months I dump and clean one of the three tubs. I restart it with daphnia and water from the other two tubs.
The Daphnia will bloom and bust but there is always plenty to feed 40 tanks of fish once a week. Daphnia is a great source of live food at a very low cost (free once you get them started). The fish love it. I always get twice as many eggs the day after feeding daphnia. And what doesn't get eaten stays alive in the tanks.