COM-100 TDS EC/TDS/Temp Meter Help

I am currently cycling my tank. Before I added salt my TDS was 499 ppm (KCI). I then incorporated salt (Instant Ocean - Not Reef Crystals). It's been two days since I added the salt and my TDS meter still hasn't been able to pick-up a reading. It just shows this "---". I have a MaxCap RO/DI top-off system and know my water is at zero coming out and into my tank. The salinity is 1.01 while cycling.

I then called the manufacturer and was told that my reading may be too high to read. This meter is made for aquarium use and should be able to pick this up. I also used the mode NaCl ppm. Any ideas as to what is keeping me from getting a reading?

 

Did you add water to your tank with a TDS of 499? If not where di the TDS come from?
You should ALWAYS premix saltwater in a seperate container and add the mixed water to the tank, never ever put freshwater in a system then add the salt.

You cannot measure the TDS of saltwater with a TDS meter, its way way beyond the range of the meter, even the COM-100 which is the best hobbyist grade meter available. It will measure 0 to 999 in low range and 999 to 9,999 in high range by tens not ones.
New saltwater is going to be somewhere over 32,000 to 35,000 ppm TDS and what you are seeing is its out of range indicator.

Make sure you clean and triple rinse the meter and whatever you are capturing the water in extremely well with 0 TDS RO/DI or you will foul and ruin the probe.

Only test tap, RO and RO/DI or distilled water, never salt water and always triple rinse with RO/DI between each test then when you are done so the meter stays clean and accurate.

NACL ppm is the correct method to use for our hobby.

Bring your salinity back down to around 1.025 or 35 ppt for the cycle, you do not need that much salt.

 

Thanks for your reply. I wasn't able to find anything on the web. I did mix the salt in a separate tub. Water coming from my ro/di is at 0ppm. My tank with no salt was at 499ppm using only DI.

I called the manufacturer again and was told to sample the tank water in a cup with the same amount of DI water and I will have a range. I used 100ml of my reef water with 200ml of DI and got 399ppm. I'm thinking my TDS is at 2399ppm. What do you have to say of this method of testing?

 

Saltwater is well over 32,000-35,000 ppm TDS so you would have to do a much bigger dilution that that. Its of no use anyway snce TDS doesn't tell you anything other than something electrically conductive is present. It could be salt, calcium, phosphates, nitrates or magnesium, or ??? You have no idea since TDS is not a measure of anything specific. TDS is strictly a measure of how pure treated water is in comparison to tap water, thats it.