Live vs Non-Live
As of November 2010 I am no longer culturing live phytoplankton for use in rotifer production or larval rearing. After extensive discussions with Matt Pedersen, Randy Reed and Gresham Hendee I had to re-think my earlier conceptions about the pros and cons of using live phytoplankton. Instead of reiterating Matt Pedersen's conclusions I'll simply provide a link to his article from ReefBuilders:
I have since started using RotiGrow Plus and RotiGreen Omega both of which are produced by Reed Mariculture. I'm just as impressed and happy with the products as Matt is and find the overall costs, results and time savings to be worth it.
You can read more about the products here:
When using the greenwater method, and feeding rotifers, there is a variety of different phytoplanktons to choose from. The most common are Nannochloropsis occulata and "Tahitian Isochrysis" (T-ISO). Both are easily cultured and provide good nutrition for rotifers. They also provide the proper essential fatty acids and lipid content needed by larval fishes for good developement. Other varieties are Chollera, Nannochloris and Tetraselmis.
Once you decide on which type you want to use you have two options to consider... "Live" phytoplankton that you can culture yourself or prepared algae "pastes", also called "Instant Algae", available from Reed Mariculture. (See the Resource page) Each option has it's pros and cons to consider.
Helps maintain water quality (Ammonia control)
Inexspensive? (Not really)
Easy to culture
Not concentrated (Necessary volume may overwhelm a rotifer culture vessel.)
May alter pH
Needs light to grow
Easy storage (Can be refrigerated, some types can be frozen.)
Highly concentrated (A little goes a long way.)
Will not alter pH
Does not require light (This works well for rotifer cultures that don't require lighting.)
Expensive? (Not really)
Will not help to maintain water quality
Originally, I used a combination of both live and non-live, depending on the situation. I fed my rotifers with Rotifer Diet from Reed Mariculture, a mix of Nannochlorposis and Tetraselmis. I also used this with my clownfish larvae.
For dottyback larval rearing I use a mix of both. Since dottyback larvae seem to do better with a 24hr photoperiod I add live Nanno as well as the RotiGreen Omega. The live Nanno can take advantage of the full time lighting and help with water quality while the RotiGreen provides a mixed lipid profile that helps with larval nutrition. Dottyback larvae are smaller and feed on rotifers for a longer period of time than clownfish larvae. If copepods are available they are a better source of nutrition than rotifers and 24 hour lighting is not needed.
It's my "theory" that uness you have a high volume of larvae that will consume all of the rotifers provided, the combination of the reproduction of the live phyto and rotifers can keep up with the demand.
In other words; the live phyto grows continuously and provides a food source for the rotifers to reproduce. Thereby providing a constant supply of rotifers for the larvae. The addition of the RotiGreen keeps the rotifers reproducing and nutritious as well as providing the benefits of "greenwater".