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Old 05-15-2015, 04:32 AM
GpsFrontier GpsFrontier is offline
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Join Date: Mar 2009
Location: Lake Havasu AZ.
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On smaller scale recirculating systems, they simply change the nutrient solution regularly to ensure a balanced nutrient solution. On large scale recirculating and water culture systems where it's not reasonable to change out large volumes of water regularly. Either the water or the plant's foliage is lab tested (regularly) to determine if the nutrient solution is balanced. If not, then only the depleted mineral salts are added back. Through regular testing it's fairly easy to see a pattern in order to add specific mineral salts at specific times to maintain a balanced nutrient solution for a specific crop.

Typically with computer controlled systems that use a reservoir the EC and pH is monitored and/or adjusted in the reservoir. Not in feed lines to plants unless the system/computer is capable of determining and adjusting the injection ratio variables on a continues basis. But plants don't use nutrients evenly, they take what they need and leave the rest. That means even if your EC readings are at the same level when your nutrients were fresh, over time the balance of those nutrients will change. Eventually you will have deficiencies of some, and others will be at toxic levels, even though the EC reading is exactly the same. That's why injectors aren't typically used in recirculating systems except to adjust pH, or add specific mineral salts at specific times that are known to be depleted quicker through lab testing. Each different mineral salt and pH adjustor (up/down) will need it's own injector and feed lines.

I fill up the reservoir before dawn and set the nutritients to be dosed when the reservoir is at full. After that only pH and EC will be corrected until the next morning.
Are you planing to change the nutrient solution in the reservoir each day? Or is this a non-recurlating system. Where does the water go once it reaches the end of the NFT gullies/tubes?
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