Friday, February 5, 2010
UPWELLING AND UPWELLERS
If you want to grow a volume of oysters you need to buy a bunch of seed and at $25/1000 a million oysters gets expensive. So this would be the first reason to have your own upweller. An upweller allows you to purchase seed directly from a hatchery at a much smaller size and price. Right now 2mm seed from a hatchery wil run you anywhere from $7-9/1000 based on strains and genetic characteristics (triploid/diploid). Picture with penny shows 2mm seed.
Some hatcheries will even go a little cheaper by selling it to you a bit smaller say .5mm, this gets a little tricky for some because .5mm is SUPER SMALL!! This stuff acts like dust once it gets dry and will blow away and its near impossible to varify the count (infact we wonder if the counts at this size are as accurate).
What is upwelling and why does it work?
You can upwell or downwell; one moves water up, one moves water down...the diagram explains it better.
When you are trying to set spat on microculch (tiny pieces of oyster shell) to get single oysters a method known as downwelling is used and is most frequently a closed system (recirculating water). Once the spat are set upwelling is used and it can be an open or closed system but the methods we will refer to are all open systems or flow through.
Upwelling brings a constant supply of nutrient rich water past your animals. All they need to do is open up and feed, which they do constantly as long as the food is in the water. This method produces hearty oysters in short order that continue to feed at a rapid pace when placed out on the farm.
Since our spat come so small we use a bucket upwelling system first.
As you can see in the picture its a series of buckets (in this case literal 5 gal buckets) that have mesh in the bottom and hold the seed. The buckets are in 4x10 tanks. Water is brought into the tank from a 4" pump (low pressure high flow) which fills the tank and the only way for the water to escape is to pass up through the buckets, taking the algae rich water passed the young oysters. The water is then sent back into the bay. Bucket upwelling is a simple priciple that can be applied to any size tank, container, or bucket. This method is great for handling small seed but inorder to get speed and volume it is essential to move to a floating upweller system.
We reccomend and offer two kinds of floating upweller systems...BIG and BIGGER.
Both systems operate on a similar principle...remove water from a trough, the trough is filled back up by a silo and the seed sits in the silos. The big one is an 8x20 floating dock with a fanblade sumersible pump that moves the water out of a trough @ 800gpm and can handle 1million animals. The bigger one is a 20x30 floating dock that uses a paddlewheel to move the water out @3000gpm or more, and handles 10 million or more animals and is expandable.
Bonuses to these systems are...
- cheap to run
- high rates of growth
- high animal capacities
They are inexpensive to run because you are moving the water laterally so gravity and equilibrium take care of the rest of the work.
8x20 FLOATING UPWELLER
KIT When you buy the entire kit you get everything pictured above and we supply the hardware and instructions so you can build the frame below (you purchase the wood on your own).
Upweller floating dock finished with doors, ready to launch. Below in use with doors up, doors are optional, make for a nice working surface when shut, and looks just like a floating dock. Complete upweller assembled and deployed.
PADDLE WHEEL UPWELLER
Cleaning upweller (note the gantry for hoisting)
Paddle wheel assembly being hoisted into place. Includes, paddles, drive, chain, sprockets, speed control, motor, chassis, safety housing, shaft and drawings for trough, silo sections, and floating dock. Easy to truck to your location country wide. Silos can be purchased directly from us as well
PADDLE WHEEL ASSEMBLY (front right)
PADDLE WHEEL ASSEMBLY (back left)
Guards for paddle wheel and drive system. Its chain driven, its not stopping...
Flow through one of silos. The trough on the first one of these was made out of fiberglass and that had to be changed to a galvanized one because the paddle wheel drew so much water it ripped the fiberglass trough off. Its metal now, no worries.