Ocean Water TDS

Does anyone know what the TDS level is where most of the fish and corals come from? Do the different islands bodies of water TDS level differ? I am getting 0 TDS from my RODI unit and just wanted to compare to where these animals came from.

 

TDS of ocean water is going to include salts, elements, etc. so, it would be better to compare the TDS of your mixed saltwater to that of the ocean, although it wont mean or tell you much.

 

annies right,0 tds means its pure h2o, ocean water isnt pure at all as thats why its called saltwater lol

 

A close to zero TDS (Total Dissolved Solids which can also be converted to conductivity) reading is pure water. Conductivity is a more appropriate measurement for sea water, natural sea water has a conductivity of 53 mS/cm. See Randy Holmes article for more details:
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You can't measure saltwater TDS, it would be off the charts. Even adding alk buffer into a 0ppm TDS RO/DI water will jump the TDS into the >100ppm range.

 

It depends on your TDS meter and you would need to know the conversion factor it is using, all in all a pain. It would be much easier to buy a conductivity meter which would give a more accurate and measurable result. This would only give you a realistic measurement for freshly made seawater, aged water in your tank would have other ions associated with it which will change its conductivity. This is one of the limitations of using a conductivity meter, if the conductivity is higher or lower than it should be, the reading won't tell you the reason for this. You would have to carry out a lot of other tests to work out why it is higher, for this reason it is only really any good for measuring new seawater. I prefer to just use a calibrated hydrometer when making up seawater and use the standard tests on the sea water in my aquarium and leave the conductivity measurements for freshwater. I am currently using a conductivity meter at work to measure the build up of organics in a breeding system to help manage nutrient content.

 

wouldnt a orp reading be pretty close to a purity reading for seawater atleast from organics?
this is one area im not up on

 

ORP is how oxidative or reductive the enviroment is, essentially as an indicator of how anoxic or aerobic the water is. It is mainly used in denitrators looking for a reductive/anoxic environment to culture anaerobic bacteria and in ozone treatment looking for a more elevated oxidative environment indicating O3 break down to O2 which causes the extra O molecule to attach to and steralizes pathogens/bacteria and other molecules in the water etc. Just using an ORP measurement doesn't however indicate exact purity to my knowledge, just what sort of environment it is.