Aquaponics Prawn and Tilapia

[TCLynx]

Sorry I don't know that article.

[urbanfarmer]

Oh boy... the conductivity of water is the conductivity of water... sticking electrodes into a sample or your main system will likely give you a pretty poor number at best. You would want to sterilize and filter sediment out of the water. Organic matter can easily affect the conductivity reading. Okay, assuming you've done this then what? The EC reading is not particularly useful because you have no idea what went into the water. So many chemicals (including byproducts and metabolites) can affect the EC of water you can not draw any real assumptions of the chemical makeup of the water from 1 number. To put it bluntly, it's just plain impossible.

AND, I still say nitrate is non-toxic to fish.

I had a thought on the stunted growth some of you have mentioned in association with higher nitrate levels. Did you know nitrate can turn back into nitrite? Ya, under certain water quality conditions this can happen quite readily. We all agree nitrite stunts fish growth (and of course kill them). Perhaps there's your real explanation???

[urbanfarmer]

Slightly off topic, but related to the "tough" fish... I just had a Tilapia fingerling fall 2 stores into dirt and I took my time in saving his stupid little butt... I put him back in water and he's swimming it off... I have yet to see a goldfish do this, but I think it would definitely be the ultimate fish challenge...

[TCLynx]

Definitely, under really high nitrate conditions and in situations where low oxygen levels might exist somewhere in the system, you can get what is called de-nitrification and the first step of that is the nitrate turning back into nitrite. Some pond and koi systems use this on purpose since they don't have enough plants to use up all the nitrates and they want to avoid nitrate build up but the second step is pretty important, you have to get the nitrite to degass into the air as nitrogen gas, other wise you just wind up with nitrite problems in the system. So unless you are running baki showers or something similar, you want to avoid the low oxygen situations that might cause nitrate to turn back into nitrite.

[rfeiller]

Setting up denitrification systems were at one point during the reef wet dry hay day the big deal. It took awhile to figure out that denitrification was being performed by the corals without our help. It was a very slow tricky anerobic process.

[badflash]

Nitrate levels are not a problem with tilapia until they get well over 200 ppm. Some fish are more sensitive, but most cichlids are not. I know this from personal experience.

[JCO]

OK, everyone including myself has jumped on the bandwagon here to show off our expertise, however the member "GSDbreeder" who started this thread has disappeared. Are you still with us GSDbreeder or have we dumbfounded you and caused you to loose interest?

[TCLynx]

Probably busy doing research into the myriad of things we have mentioned for his monumental project.

It is a pretty major undertaking. In the mean time I hope he gets a "backyard" scale system going that can help teach him what he will need to know.

[JCO]

OK, it's beginning to look like I was correct...I PM'ed GSDbreeder and also sent him a regular email with no response to either. I guess we completely overwhelmed him or he found another forum with more helpful members..

[rfeiller]

I Have to quit hyjacking threads.
What he wanted to accomplish in fish production alone requires a good size operation. I wish him well. Don't know what life would be without a German shepherd by my side.