Dear AP Folks
Im looking for a NFT Filter and sump sketch. Also, it would be very helpfull to see photos of a sump or a filter. Maybe someone has some extra insider clues how to make the nft system work.
Has anyone experience with integrate duckweed in the system, used also as a biofilter? for every information i am very thankfull!!!
A sump is just the lowest tank in a system where water can drain to so the pump can lift it back up around the system.
Here is a link to some diagrams I have done over the years, they are all very basic just to give ideas.
There are some extensive threads on Duckweed. Kobus is doing much research into duckweed actually. Duckweed can use up a lot of ammonia directly though and isn't so much a bio-filter (bio filters are where the bacteria that convert ammonia to nitrite and nitrite to nitrate live and they co-exist in the grow beds of media based systems right with the plants.)
thanks TC, a really big help....now i just have to figure out how big the sump have to be and the box at the end of the nft pipes where the water run into and the pump, pump it back to the fish tank. nft pipes are the standard commercial ones, and fish tank is a 1000 l tank (same murray hallam use) :D thanks again for the reply it really helped.
To figure out what size sump tank you need, you have to estimate how much water will be in all the NFT troughs and any pipes of the system when the pump is running. You will need a sump tank big enough to handle that amount of water fluctuation plus enough water that the pump isn't anywhere near running dry while things are running and perhaps enough extra depth for a top up valve between the normal water level and the pump in danger level. So that the top up valve will only add water when the water level drops below normal.
So if say there is about 50 gallons in all the pipes, plumbing and the slight rise of water in the fish tank when all is running properly, then you probably want a 100 gallon sump tank so you can have around 40 gallons in reserve for the pump to work in and when the pump shuts off the sump tank won't overflow as all the water drains into the sump from the pipes. The larger the footprint of a sump tank the more excess volume you will need in it since most pumps don't work in very shallow water.
I wish I could offer you a visual diagram, but perhaps our imagination will be sufficient for this one. I firmly believe that a hybrid system will be the easiest way to proceed when using Aquaponic NFT. Trying to use baffles, artificial biofilters, solids removal systems, etc. can be a royal pain! Here's a simple and cheap design that has worked for me and my family flawlessly for 8 months with almost no maintainance:
Fish tank and sump tank are side by side. Water is pumped from fish tank to traditional gravel filled grow bed. This uses a bell siphon to create ebb and flow. Inside the gravel bed are composting red worms. Clarified water leaves gravel grow bed and falls down into "sump" tank. Second pump in sump tank pumps filtered water to NFT channels. Water flows through channels and returns to fish tank.
From the research I have done, 20 gallons of fish water can supply a 4 x 4 foot NFT setup. Your gravel growbed needs to be capable of holding the same volume of water as the fish tank to properly filter everything. In this setup, the growbed is 20 gallons as well.
The beauty of this system is that the gravel bed will filter your water and provide an everlasting spot for your nitrifying bacteria without the complications of a baffle tank and artificial biofilter. The composting red worms will EAT the solids and convert them to an extremely soluble form that can be readily taken up by the roots of the plants. This means that you will never have to dispose of any solids from your system if properly sized. The red worms will naturally multiply and regulate their own population as the levels of solid waste accumulates.
The whole system described above cost us about $300, and produces more food than my family can eat each week!
I hope this helps. Good luck whatever you decide!
Please can you give a photo.
Many many thanks,