How often should the water be cycled so as to ensure that water in the grow beds is already purified by the plants? Also, when water from the fish tanks is pumped up to the grow beds, doesn't it get mixed up with purified water? And are we not getting this mixed water again in the tanks via bell syphon?
The question has to do with standard ratios of plants, growbeds,fish numbers, water volume being transferred etc. Read this document(link below) and if you still have any questions please post them here.
I am cycling a small grow bed of expanded clay using an operating system by pumping all the water through the new bed and then into the old bed. How long should it take to cycle this way?
Siddharth, I don't think you're looking at this concept from the right direction. It's not really about the "clean" water and "dirty" water. Waste levels are measured in ppm (that's "parts per million"), so it's more of a ratio of waste to water throughout the whole system.
Fish are constantly excreting waste as part of their living in the form of ammonia. Fish waste is only toxic to them at certain levels, so the job of the plants is simply to keep the water/waste ratio at a level that is safe for them. Ammonia is very toxic to fish, so that's where our nitrogen cycle is important. Bacteria convert fish ammonia to nitrite, and then ultimately to nitrate, which is a form of nitrogen that is far less toxic to fish, and more accessible to plants.
Think about it like this: You are on a ship that has sprung a leak. In order to keep your ship from sinking to the bottom of the ocean, you have to find a way to manually pump your water off of the boat. It's not important that you get every drop of water clear from the hull; ships are made to carry the weight. But you need to make sure that the water levels don't get so high that your ship begins to sink.
Ugh, there I go answering old questions again XD Hopefully that helped you Siddharth, if you're still around....
Jeff, if your old bed is already cycled, the bacteria should move in pretty quickly. Make sure there is adequate food present for your bacteria (i.e. ammonia). Also, the more ideal your water conditions are, the faster your bacteria will colonize. Bacteria hit their ideal at about a pH of 8.0 (if you've already got plants in your system, then it's better to keep things at the 6.8-7.0 range, or your plants could have problems. Although, you can probably push it at 7.6. If you are supplementing iron, make sure you get a grade that your plants can absorb at that pH). Keep things warm too.