Water Flow

1. Water is continuously pumped from the reservoir into each of the four fish rearing tanks. A 3" PVC distribution pipe connects the circulation pump to an outlet at each tank. Water flows from the pipe into the rearing tank.
   
2. The addition of water to the rearing tank forces water, by hydrostatic pressure, through a center bottom drain. This drain is screened with a 3/4" vexar sock to prevent fish from exiting the tank. A tubular sock is used. (A flat screen, flush to the bottom of the tank, can get clogged with dead fish.) The water flows through 4" PVC pipe underground then up and through a connection in the side of the clarifier tank. The pipe connection to the settling tank is about 8" below the surface. In effect the water level in this settling tank is the same level as water in the rearing tank. The water from two rearing tanks feeds into one settling tank.

   In this quiescent tank solid fish waste, feces, settles to the bottom of the cone. At the bottom a valved drain pipe is connected to the tank which can be opened and the collected solids removed. This task is performed 2 - 3 times each day. Approximately 20 gal. of water are removed from the system.

   It is very important to remove all solid waste from the water flow. Solids wastes are a high organic load and, when they decompose, oxygen, intended for the fish and plants, is removed from the water. In the much larger and slower flowing hydroponic tanks these solids will settle and their decomposition will remove oxygen from the plant root zone. Solids also become trapped on the plant roots and reduce their ability to absorb water and nutrients.
   

3. Water pours (about a 4" drop in tank levels) out of the settling tank and into the first of two rectangular net-filled tanks. It flows into the second tank through a submerged 6" PVC pipe.

   Bird net in these tanks traps fine suspended solids that did not settle in the settling tank. The bird net is washed each week and collected solids are drained from the tank.
   

4. Water leaves the second rectangular net-filled tank and flows into the degassing tank. 
   
5. 
   
6. and joins the water flow from the second set of rearing/settling/ rectangular tank series. Water is then divided into three distribution lines directing flow to the cylindrical head tanks. See the note above regarding system components and the consolidation of hydroponic tanks into larger units.
   
7. Water upwells into the head tanks. The full tank pours water from an outlet into the hydroponic tank.
   
8. Water flows down the length of the hydroponic tank. At the far end of the tank a drain has been installed with connecting pipe to the returning hydroponic tank. Water flows down the length of the second hydroponic tank. Through a drain at this end water leaves the hydroponic tank to join other returning water in a 4" PVC pipe returning flow to the reservoir tank.
   
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