Note: This is not a system we are selling - we are giving away the research and design for FREE. This system can easily be built at your facility from parts you already have or can get from a local supplier. The only piece that is challenging to make is the Rotary Drum Filter and that will be available for sale on December 1st from distributors in the USA and Europe. To see pictures of our ICR system click here.

Traditional Growing Approach

The traditional technique for growing rotifers is to use cheap food sources like yeast to feed low density tanks. A starter culture of rotifers is added to the tank on the first day. For the next 3-4 days the tank is fed with yeast while the rotifer culture is growing. The tank rapidly becomes fouled as uneaten yeast and rotifer waste clump and settle to the bottom and start producing large quantities of bacteria. The key to success is harvesting the rotifers before the tank becomes too badly fouled and causes the rotifer bloom to crash. This technique is labor expensive, requiring frequent monitoring, intervention, and time spent cleaning and restarting tanks.

Instant Algae Rotifer System

The key to this system is a high quality, non-fouling, bacteria resistant feed like Instant Algae

The Instant Algae Rotifer System takes a completely different approach to rotifer production. Instead of trying to out-compete a rapidly fouling environment over the short term, the Instant Algae system maintains a clean environment (low bacteria, almost ciliate free) where the rotifers can grow at their maximum potential indefinately. This is done through a combination of innovative system design, low cost equipment, and most important - high quality, non-fouling, bacteria resistant feeds

It is normal for a healthy rotifer culture to double in quantity every day, consuming relatively little food and producing little detritus (rotifer droppings and uneaten food). Rotifers can be continuously grown and harvested at very high densities if they have optimal conditions:

• A non-fouling, bacteria resistant feed high in nutrients (microalgae with whole, intact cells)
• A clean, non-toxic media (low bacteria, low free-ammonia levels, no ciliates)
• A stable, optimized environment (temperature, pH, oxygen, feed level)

When conditions are less than optimal rotifer egg counts drop, feed must be increased, detritus and ciliate contamination become a problem, and productivity suffers.

The critical component in this system is the feed. To keep the system running there must be no "sticky" fouling inside the tank. Traditional feeds such as yeast and fish oil emulsions promote rapid bacteria growth which cause detritus to stick together in clumps, and stick to the walls of the tank.

The best feed for this system is "Instant Algae" microalgae concentrates. Instant Algae cells are small (1-5 microns), whole and unbroken so they:

• Are highly resistant to bacteria
• Do not stick to each other or to the tank walls
• Stay suspended in the water column

Although Instant Algae is more expensive than yeast, the cost is more than compensated by reduced labor costs - only a few minutes each day, and 1 hour once a week. Additional savings come from reduced space (1 / 10th the space needed), reduced water usage and heating, and reduced risks from having a consistent, reliable system that is resistant to crashing.

Overview

The system starts with a large tank where the rotifers are fed and grown. The rotifers are fed by a continuous drip of Nannochloropsis 24 hours each day. There is also a continuous drip of ClorAm-X into the tank to detoxify the ammonia. The tank has a conical shaped bottom so the detritus is concentrated as it settles to the bottom. The water and detritus are pulled from the bottom of the tank by a pump and filtered through a mesh bag. The mesh bag collects most of the detritus but passes the rotifers thru without damaging them or detaching their eggs. The clean rotifers pass through a rotary drum filter where the rotifers are collected and pumped back into the main tank while excess water is discarded or sent to a biofilter to be re-used. The water in the tank is turned-over at a rate of at least 200% each day. The excess water can be recirculated by running in through a biofilter to eliminate ammonia and other impurities, then stored in a tank. Harvesting is done through a gravity flow hose located 1/3 of the tank height from the bottom. The rotifers can be harvested directly into 20 liter buckets, or concentrated through mesh bags or wire screens. For best results harvest 2 or more times each day.

Recirculating System

The ICR system can be run flow-through (as shown in the diagram below) or as a recirculating system. To set the system up for recirculating you need an additional tank that is at least twice the size as the main as the rotifer tank and it needs to be set up with a biofilter. This is necessary to break down ammonia and and other compounds in the water. The ClorAm-X detoxifies the ammonia but does not remove it. Once your biofilter tank is set up, connect it to #1 (New Water) and #3 (Drain).

System Flow Chart

Narrative / Description

1. New water is constantly being added to the system.
2. Detritus heavy water is slowly pumped from the bottom of the tank and run through an 800 micron filter bag. This catches the detritus but allows the rotifers to pass through without damaging them or separating their eggs. If the detritus filter bag is lower than the top of the tank there will be no need for a pump since gravity will move the water. A more sophisticated system could use a float-valve to regulate the flow of water and shut off the flow if the water level in the tank gets too low.
3. The clean rotifer culture is passed into the rotary drum filter. This device allows water to be removed from the system without losing any rotifers.
4. The clean rotifer culture is pumped back into the main tank.
5. Microalgae and ClorAm-X are pumped from the refrigerator into the main tank
6. Rotifers are harvested daily from the Rotifer Harvesting Port. This is a gravity-flow port and located midway up the tank to prevent the entire tank from being accidentally drained.
7. Water from the drain (rotary drum filter) is run through a biofilter, stored in a tank, and then put back into the system (#1).

Equipment

I will add information to the website soon on where you can purchase this equipment. A source for the low volume pumps should be posted in a few days.

Item	Description	Quantity	Price
Tank	Conical Bottom	1	$200-$300
Pump - very low volume	For pumping the algae concentrate into the main tank. Will typically pump less than 1 liter each day.	1	$125
Pump - very low volume	For pumping the ClorAm-X into the main tank. Will typically pump less than 1 liter each day.	1	$125
Pump - low volume	For pumping the rotifers from the drum filter back into the main tank. Will pump 300% of the total tank volume each day.	1	$125
Small Refrigerator	To keep the algae cold	1	$100
Filter Sock	800 micron - for collecting detritus	1	$10
Oxygen Source	Pure O2 is recommend, either from a tank or generator
Rotary Drum Filter	Collects rotifers while allowing water to escape from the system	1	$150

Reed Mariculture's Production System

Tank Size	300 liters
System "UP" Time	Running continuously since March, 2002
Stability / Densities	Reliable daily densities of 2,000 to 2,500. Once every 3-4 weeks the density drops by 30-60% and takes 2 to 3 days to recover
Harvest Rate	65% daily on average
Harvest Quantity	390 million per day
Water Quality	The water quality in the culture is always very clean
Ciliates	Almost none
Feed Rate & Cost	0.8 liters of Instant Algae Nannochloropsis daily = ~ $0.10 per million rotifers
Daily Water Turnover	300% (900 liters)

Frequently Asked Questions

What are the daily and weekly maintenance tasks?	Daily Wash out the filter sock that collects the detritus 1-2 times each day Scrape the insides of the main tank with a magnetic scraper Weekly Refill the algae and ClorAm-X supplies Clean the drum filter
How large and small can the main tank be?	It does not matter, so long as it is a conical bottomed tank. We recommend a slope of at least 60°.
How much ammonia is acceptable?	When using ClorAm-X ammonia will be in two forms - "toxic" and "non-toxic". Toxic ammonia (also called free ammonia) is converted to "non-toxic" ammonia by the ClorAm-X. Total ammonia is the combination of toxic and safe ammonia. Toxic ammonia should be no higher than 1 ppm. Total ammonia will range from 6 to 10 ppm.
How much ClorAm-X is needed?	150 grams of ClorAm-X for each liter of Nannochloropsis.
Do I need pure oxygen?	We add pure oxygen from an oxygen generator to our system because it is convenient. We have not tested the impact on the system if the oxygen is replaced with room air, but suspect densities will fall in high density cultures.
What is the temperature range?	Our system varies between 23 and 29 C. A more consistent temperature would probably result in better production.
What salinity is your water?	28 parts per thousand
What is the pH?	We have seen a range from 7.8 to 8.5, and the current pH is 8.2
What cause the periodic density drops in your system?	80% of the time it is operator error (forgetting to refill the algae or ClorAm-X bottles) or equipment failure (somebody unplugs a pump and forgets to turn it back on). 20% is variables we are still trying to understand.
Does the system need to be harvested at 40-60% each day?	No, but a high harvest rate stimulates faster daily reproduction. We have seen two growth modes with the rotifers: 30% harvest and a 15-25% egg count, or 40-60% harvest with a 40% egg count. If you use the same amount of feed each day the system will find an equilibrium based an the amount you harvest each day.
How are the rotifers harvested?	By using a gravity flow pipe. We keep the end of the tube above the level of the tank, then lower it for harvesting. 2/3 of the tank is above the tube fitting so it will pour out quickly, but cannot completely drain the tank. For best results harvest 2-3 times each day.
Is it better to run just one system, or have two smaller systems	Redundancy is always a good idea so we recommend at least 2 systems to ensure a reliable supply of rotifers.
Are there any special lighting requirements?	Yes - keep the main tank as dark as possible. Rotifers do not need ANY light, and light stimulates the grow of fouling organisms. Our tank is painted black and covered with black cloth.
What are the costs of maintaining the system once it is set up?	The on-going costs will be 1) microalgae concentrate 2) ClorAm-X 3) electricity for the pumps
What is the Rotary Drum Filter	This is a mechanism we designed that will capture and concentrate the rotifers and send them back into the main tank while allowing water to exit the system, to be recycled or disposed of. We will publish more information about this soon.
Where can I get a drum filter?	These can be built in-house, or will soon be available from suppliers in the USA and Europe. We will publish links to these suppliers in mid November.
Why is a refrigerator necessary?	Instant Algae needs to be kept cool. If a refrigerator is impractical you can keep the algae in a bucket with water and frozen gel ice packs.
What is the daily turn-over rate?	300% or 3X the tank capacity.
Why are there almost no ciliates in this system?	It appears that ciliates are attracted to and stick to detritus. The detritus settles to the bottom of the tank where the water is removed from (300% each day) and filtered, so ciliates are rapidly removed from the system.
Are the rotifers enriched?	Enrichment refers to lipid levels, both EPA and DHA. If you feed the rotifers on Nanno they will have a very high EPA level but no DHA. For DHA enrichment we suggest switching to Pavlova for a few hours prior to feeding the rotifers to your fish. Pavlova performs as well as Nanno, but the cost is slightly higher.
Where can I find more information about growing rotifers?	Take a look at our "Rotifer Recipe" page. It provides a lot of information about growing rotifers.