Reef Discussion

[VaultBoy]

I have just bought this meter and it has 3 selections for correction factors to convert EC (electrical conductivity) to TDS and I dont know which one to use. Can someone with a TDS meter look in the booklet and see if it tells you what correction factor it uses to calculate the TDS?

At work we use conductivity and resistivity to test how pure water is as TDS is a product of conductivity, temperature and a conversion factor made up based on an assumption of what is in the water. The only real way to test TDS is to evaporate the water and weigh whats left over. I think everyone should be using EC insted of TDS to test their RO/RODI water but Im not gonna change the world by whinging!

 

[callum@psi]

correction factor for temp?

 

[VaultBoy]

Electrical conductivity changes with the temperature and is measured correctly at 25DegC and this unit corrects the reading for the temperature of the solution being measured.

 

[callum@psi]

yeah its correction factor is 2% per Deg C

 

[VaultBoy]

Thanks Callum but I should have been more clear I understand the correction for the temperature. I meant the correction for what is assumed to be in the water. There are correction factors for KCl - potassium chloride, NaCl - sodium chloride (salt) and 442 which is an artificial imitation water from what I can gather. I am wondering which factor the generic TDS meters use as mine has more options than most and I want to compare apples with apples when talking to people with other meters.

 

[VaultBoy]

I should mention that I just changed my filters and resin on my RODI and reading before was EC 5.6uS and TDS were ~340, ~600 and ~400 on the 3 conversion factors and after the change I got EC 0.2 - 0.4 uS and TDS were 0.3, 0.3, 0.2.

 

[callum@psi]

NaCl EC-to-TDS conversion factor, which is an average of 0.5.

And thats directly off the HM DIgital website.

callum

 

[VaultBoy]

Thanks!

 

[callum@psi]

we are actually a hm digital australian agent. We dont even currently stock the COM-100. May have to look into stocking it.

 

[VaultBoy]

Its a great unit. They feel like very high quality build. As their agent do you stock the 4.0 and 7.0 calibration fluid for the pH meters?