I have been cultivating live food to be used in my reef tank for a while now. The overall effect on the inhabitants of the tank has been quite successful. Overall, I have observed the growth and health of the animals in the tank improving, with little, if any, degradation in water quality.

I feed more rotifers to the tank than phytoplankton. Currently, I am feeding the tank 1/2 cup of phytoplankton only 2-3 times a month and about two gallons of rotifers run through a sieve every night. I presently feel that the corals get more of a benefit from the rotifers than they do from phytoplankton. The phytoplankton is fed mainly for the benefit of sponges, feather dusters and other benthic creatures that consume them. But since this is a coral tank, rotifers are the primary live food being fed to the tank.

If you are looking for more information on the benefits of feeding rotifers or other zooplankton substitutes to your coral, please read Eric Borneman's article in the December 2002 issue of Reef Keeping Magazine.

Basically I have all my cultures growing on two shelves in my fish room. The top shelf is for phytoplankton, the bottom is for rotifers. Try to remember; when cultivating you should always keep the phytoplankton above the rotifers to keep cross contamination at a minimum. Ideally, you should have the two in separate rooms, but that is not always practical. Also, if you need to work on both cultures, you should always work on phytoplankton first, then the rotifers.

I will try to give a brief overview of what I do.

 PHYTOPLANKTON

The Set-Up
All my phytoplankton culturing is done using empty 2 liter bottles of cola. The bottles are simply rinsed well before use. I use an air pump that goes into a gang valve to provide air to up to five bottles at a time (presently I am only using 4, that seems to be more than enough). Each bottle has a small hole drilled into the cap. I have inserted a length of rigid air tubing into the hole that goes into the bottle about ½ inch from the bottom. There is also another small hole (slightly smaller than the first) which has a piece of cotton wedged into it. This is used to allow air to escape the inside of the bottle and also keep out any contaminates.

Lighting the Phytoplankton.
I keep my cultures lit for 16 hours a day. My lighting consists of two 24" florescent bulbs. They are attached to the wall about three inches from each other vertically. I picked up the units that have bulbs and ballasts together at Home Depot for about $24 each. You can do it cheaper if you buy the larger shop lighting fixtures. I liked the compactness of the 24" bulbs, so that is what I went with. I am using standard NO lighting, I think I have 20 watt bulbs.

Culture Medium.
The culture medium is what you add to the phytoplankton to make it grow. It consists of salt water and Micro Algae Grow (a kind of miracle grow for phytoplankton). Use an empty bleach container, which has been thoroughly rinsed with tap water. Fill the gallon container with tap water and add slightly less than ½ cup of salt mix. Then add 3ml of Micro Algae Grow liquid. Shake container and let it sit for a day. Then use at your convenience.

Culturing.
This method applies to having phytoplankton to begin with. I am currently using Nannochloropsis as my phytoplankton, this is the same phytoplankton in DT's brand of phytoplankton sold in LFS and on-line. I fill ¼ of the bottle with phytoplankton to start the culture (you can use less if this is the first bottle you are starting with). The rest of the bottle is filled to about two inches from the top with my culture medium. I then put the cap with the hose attached back on, screw it on tight and put it about one inch from the lights. Turn on the pump to produce a steady stream of bubbles in the bottle. I mark the bottle with the date and let it sit. After 10-12 days (add a few more days if this is the first bottle to be cultured) the bottle should be a dark green color. Your culture may reach it's peak before 10 days, factors such as heat play a major role. If the water temperature is warm the phytoplankton will grow faster. The key is to observe when the water is not becoming any darker. Once you notice no change in the color of the water for a few days, it has reached it peak and should be removed. I remove the bottle and pour all but ¼ into a container that I store in the fridge for feeding. The rest is re-used to start the next batch.
That's it!!

For more information on culturing your own phytoplankton please read the August 2002 issue of Advanced Aquarist.

To purchase phytoplankton supplies, visit Florida Aqua Farms.

If purchasing from Florida Aqua Farms, here is the list of items you will need.

1. Phytoplankton, buy either one of the below

   MICRO ALGAE DISKS
   AA-NCP Nanochloropsus (Japanese Chlorella) green, non-motile 6 µm

   LIQUID MICROALGAE CULTURES (if you want to use live cultures to start)
   AA-LQ1 Unialgal, mass cultures of Nanochloropsus, 1 quart

2. MICRO ALGAE GROW, GUILLARD f/2 FORMULATION
   FA-MIS Micro Grow 200 ml, (400 L at f/2 level), 8.5 oz

 ROTIFERS

Culturing rotifers is not that hard. They have a tendency to crash and they need to be looked after every day or two. Also, you will need about 10 minutes per day if you plan on culturing and feeding rotifers to your tank. If you can put aside the time, rotifers are easy to raise and feed. You will also be doing your corals a great service by feeding them.

In the following, I will discuss what works for me. There are other ways of doing this that you can try. For me, the way in which I have been culturing rotifers seems to work with little worry.

Equipment
5 Gallon tank I use a 5 gallon tank, available from your LFS. They cost about $10. I have a spare and every 5-8 weeks, I swap one for the other. It helps keep up the water quality and the rotifers from crashing, so far this has worked out quite nice.
Air pump and hose I use the same pump for my phytoplankton as I do for rotifers. The last gang valve attaches to the hose for the rotifer tank. Also small suction cups for use with airline tubing available from the LFS as well.
Small lighting Use a florescent light. I have a small 18 watt florescent light I bought at home depot. I keep it about 2 inches from the tank.
Heater (optional) You may or may not need this. The winter of 2003 was very cold. The temperature in my basement stayed in the low fifties during this winter, because of this the rotifer water temperature was in the fifties as well. My cultures kept crashing and I was unable to keep them going. After I put a small heater in the tank, my crashes went away. I keep the tank around 73F during the winter. During the summer there is no need to worry about the temperature.
Food Feed your rotifers phytoplankton. Use just enough to keep the color of the tank slightly green. For me this amounts to about 8-10 ounces a day. Every few days, I skip adding phytoplankton. This seems to work well.
Plankton Collector A plankton collector is basically a tube with a polyester plankton cloth attached to one end. You would buy the 53µ mesh plankton collector for rotifers. The plankton collectors also come with a 1 liter cup.

Culturing Rotifers
Rotifers can multiply very quickly, so you need to make sure you always have enough food for them to consume. In as little as four hours without a food source they can start to start releasing cysts, so keep that in mind when thinking of postponing a feeding until the next day. You can start your culture from cysts or from live cultures shipped in salt water. When ordering rotifers, make sure you specify rotifers designated with an S (S is for salt water), as they can be for fresh water as well. I am going to assume you are starting your rotifers from a live culture of rotifers, either purchased online or locally.

First, remember that rotifers will die immediately if they experience a change in SG of more than .007. I keep my tank at 1.025, so I keep my rotifers at 1.020-21. Rotifers as well as phytoplankton do better at a lower SG. The lower the SG the quicker they will grow and multiply. But at the levels I need to use them, their growth rate is more than enough.

Fill up your 5 gallon tank with water. I use RO/DI because it is convenient, but tap water is fine. Add enough salt mix to bring the SG to around 1.020. Put in a small power head and let it mix for two to three hours. Freshly mixed salt is a little too harsh for the rotifers to be just dumped in, so I let it sit a few hours before use. Next, position your light about two inches from the back of the tank and turn it on. I try to light the tank for 16 hours a day; I seem to experience good growth using this lighting schedule and would recommend it. Put an air hose in the tank and use a suction cup for airline tubing to hold it against the front wall of the tank. Adjust the air flow to about 2 bubbles per second. Add some phytoplankton; I add about 16 ounces of phytoplankton the first time when using live rotifers. Then add the rotifers. Rotifers are very tiny, but within a day or two you should see that the water has become pretty dense with the creatures, once this has happened you are ready to siphon them out and start feeding your corals.

Once a day, I siphon out about 1/3 of the water into the plankton collector. I use a ½ inch tube and start a siphon. I siphon the water into the collector over a small bucket. After you have the rotifers in the plankton collector, turn it upside down over the cup that came with the plankton collector. Use a turkey baster to take tank water and squirt it onto the net of the plankton collector, thereby rinsing the rotifers into the cup. Do this 4 or 5 times, till all the rotifers are in the cup. Now you have just collected the rotifers that you will be feeding to your corals. Before you feed your rotifers to the tank, put the siphoned water back into the culture tank. I always add my phytoplankton to this water first before adding the water back to the tank, it helps to mix everything before going back. I also add about a cup of RO/DI water to the siphoned water to make up for any evaporation that has happen in the past 24 hours. (This is an important step. Due to the small size of the cultivating tank, dramatic increases in salinity can happen in two or three days. I now check my SG in the culture tank every few day, or anytime I notice the rotifer population thinning. Most times a crash looks to be happening, it is really just too high salinity in the culture tank. Most time bringing down the salinity levels will allow the rotifers to start multiplying in good numbers.) Then just dump the water back into the rotifer tank and you are good for another day.

Last is to feed your rotifers to your corals. I just dump the rotifers into the main display tank and leave it at that, but you can spot feed your corals if you want to.

Crashes
Rotifers cultures crash, it's a fact of life. Deal with it. Every so often you will notice that your rotifers culture seems to be getting less dense each day. Once in a while it will rebound, most of the time this is the tell tale sign of an impending crash. As long as you know what to do, it is easy to rebound. Rotifers produce cysts when they sense that water conditions are changing for the worse. These cysts lie dormant, are virtually indestructible, but will soon hatch when water condition are right for their survival. So knowing this, when you find yourself witnessing a crash, here's what you do. Mix up a new batch of salt water, add about a cup of phytoplankton. Then siphon out ½ to 2/3 of the water from the crashing rotifer tank, using the same method as above. When siphoning make sure you siphon the bottom and pull out some of the gunk on the bottom of the tank, as the cysts are down there. Then transfer the contents of the plankton collector to the new water. In about 18-24 hours the new cysts will hatch and start to reproduce, in the beginning you do not want too much phytoplankton in the water. Make sure you check every day and add a little bit more phytoplankton, just enough to make the water a slight ting of green. In about 5-7 days your culture will have rebounded. Now, just care for them as before. This method has worked for me every time, so you should have good luck with it.

Shoping List
If you are buying from Florida Aqua Farms here is the list of items you will need.

1. ROTIFER CULTURE
   

   ROTIFER CYSTS (If starting from cysts)
   AB-R1(S) Lab cultured "L" Strain Rotifer Cysts, 3-5000 cysts

   LIVE ROTIFER INOCULANTS (If starting from live cultures)
   AB-RL(S) Live Rotifers "L" strain, 1/4+ million, 1 quart volume

2. PLANKTON COLLECTOR
   BB-PC 4" dia cup, 53µ