In traditional Flow-through Aquaculture Systems, water is passed through the culture system only once and is then discharged back to the aquatic environment. The flow of water through the culture system supplies oxygen to the fish and carries dissolved and suspended wastes out of the system. Water quality within the culture system is maintained by flushing of contaminants and by replacing all system water before dissolved oxygen concentrations drop below minimum acceptable limits or contaminate concentrations (i.e. ammonia, solids, and carbon dioxide) can accumulate to above maximum acceptable limits. Flow through systems are where fish are held in ponds, tanks, raceways or other specially designed apparatus which have water constantly passing through them. These systems can be used to grow or expose either fresh or marine species.
Intensive and semi-intensive flow through culture systems are those where fish are stocked at high densities and are fed on artificial diets. Appropriate stocking densities will depend on the species stocked and prevailing environmental conditions. These systems generally require large quantities of water to allow high stocking densities without water becoming degraded through the system.
Flow through systems may be either gravity feed or use pumps to supply their water. The advantage of gravity fed systems are that there are no pumping costs involved.
The main goal of a Flow Through system connected to a peristaltic pump, is to obtain a constant concentration of an element in your exposuretanks.
You always start from a stocksolution. Attached ( and in) this stocksolution, tubings are connected with a peristaltic pump. This pump pumps your stocksolution through tubings into your exposure tanks at a certain flow rate. In your tank you'd have to provide a continous flow through, through your system, to keep the same concentration of your stocksolution at any time during exposure. From your exposuretank, you'd have to make a connection with your drainnigsystem, to prevent water rising above the top of the tank.