Backyard Aquaponics
A place to discuss aquaponics

my system has been going now for 5 weeks. Fish are good. Siphons working. Veges going strong except now know to late to plant broccoli as all flowered. but salt? ppt? doesn't it all work out? The balance that is. the amount of fish to the amount of plants. please correct me if i am wrong

We use to salt to alleviate stress from handling/transportation... or to mitigate the toxicity of nitrites (particularly when cycling) to about 1ppt...

We also use salt to treat parasites (Ich) and minor fungal/bacterial problems.... typically 3ppt... but if needed up to 6ppt or beyond for more serious disease treatments...

Pure water is rare in nature. Most water has salt in it. Fish like a certain salinity. Salt discourages illness.
Salt is removed by plants. So needs to be topped up periodically. It also adds trace elements (if sea salt) that are essential to healthy plants.

that is nice to know and if i understand we should use pool salt not cooking or rock salt

Definitely... pool salt is pure "evaporated" sea salt... table salts contain iodine and anti-caking agents that can harm/kill your fish...

Sorry for the O.T but how salty is the ocean / pure sea water?

have chatted with you guys a few times, and would like your opinion. if i was to introduce an nft system on existing system what sort of impact would that have on existing system. am looking to eleviate the current presure on my pump and extact more vegies if possible

Very do-able... but you'll need to put some sort of pre-filter before the NFT... or best might be to take the output from the growbeds, which will have already filtered the water of most solids...

grow beds don't get any solids so already done, except when i place pipe in water and suck out a little manually. how full and flowing should a nft be through a 90mm pipe 6meters long? 1/2 full and water flowing slowly and back into fish tanks is what i thought?

bentaz http://en.wikipedia.org/wiki/Seawater
Wiki is your friend.
3.1 - 3.8%
or 34.5 ± 3.5ppt

You dont need alot of water in a NFT - just a small trickle is fine as long as you have either a long cup to plant in that reaches down to the water, or you have a wick. As to what effect will it have on the balance? Not much. The extra plants will keep the nitrate levels down. Do you have plenty of filtration (biofilter)?

still planning on the plants in the grow beds and the perlite and plants in the nft to do the filtering. is this right?

I'm not sure if I follow you, do you have any pics or plans we can see?
Yes the grow beds are your main solids filter and biofilter (which breaks the poisons down into nutrients). The NFT are empty tubes with water flowing (trickling) through them. In the top of the NFT you drop in some net pots or cups. These are filled with a medium such as perlite. Plants are grown in the cups and the roots will grow through the bottom and into the NFT tubes, and the water will flow over the roots. The problem comes later if you are pumping water from your fishtank directly into the NFT. Your fish water will contain alot of solid organic matter (mostly poo and fish food) which will stick to the roots of the plants in the NFT and eventually form a sticky muddy mass that will choke the plant of oxygen. To prevent this you need to put some sort of filter between the fishtank and the nft tubes to take out all of the solids. This could be a purpose designed filter, or it could be the water coming out of the growbed on its way back to the fishtank. The perlite in the cups will not filter out any of the organic material.

now i understand thank you will do pics soon.

is this a sily question - what are nft's?