I can"t address any of your questions, but if you read "Aquaponics 101" (it's right under the DIY Aquqponics logo) I am sure you will find your answers. I highly recommend starting at the beginning and take the time to read and comprehend all the material. I am STILL designing my first system and frequently revisit to refresh my knowledge. Hope this is of some help and "Good luck" to you on your hydroponics/aquaponics system builds in the future. aquaally