Very helpful thread, just bought myself a TDS pen and worked out its conversion is 0.5, Getting readings on some new tanks that are cycling of 150PPM which i think is good. (plan on keeping crs/cbs)

Thanks again mate.

Can someone provide some example maths using these "conversion factors" sorry?

Because I'm trying to get my head around how it works as I use Bluelab's way and the way typically adopted in Aquaponics.

From EC to ppm500 (American) EC of 0.4*500= 200

From EC to ppm700 (Aus standard) EC @ 0.4*700= 280

So working backwards if I knew my TDS on an Australian meter I'd divide by divide by 700, or an american meter I'd divide by 500 both bringing me back to the 0.4 EC I know to be true...

So I cant help but wonder as I have trouble following the OP what maths everyone else is using? and whether perhaps as people are using different meters with different equations we should actually adopt the international standard of EC ratings like as being seen in the Hydro/Aquaponics industries? Might help make water parameter discussions a little easier as we'd know we're all on the same unit of measurement. Just my 2c

-edit-

This is driving me mad, Because as an example of converting days to hours the conversion factor is "24". 2days*24 = 48 (Hours)

But if you were to try to get from say an american TDS of 200 (that's 200 @500ppm) then multiplying by 0.5 would get you to 100, when the EC rating is actually 0.4 and would be attained with a conversion factor of 0.002 (200* 0.002 = 0.4)

I feel like I'm missing something obvious here :/

I don't think it's possible dude, you'd have to get all the manufacturers of TDS pens to work off a standard conversion factor. The only one that is standard measuring device is an EC pen as they all use the same measuring unit without conversion. The thing with TDS pens is it all depends on what chemical they are calibrated with, whether it's NaCl or KCl, they both have a different conversion factor from EC. :encouragement:

Sorry but Bluelab truncheons don't even need calibration, which is what I use. Joys of a device that displays CF, EC, ppm500, ppm700 and needs no calibration to use...

I'm just trying to figure out this headache that others have to go through, which it sounds like anyone with a TDS pen should be doing. Otherwise when you all display your ppm ratings of your water parameters without knowing how it's being calculated then it's not that useful. It would be like having multiple ph scales in use but not being able to directly compare them.

If all probes read at EC, then convert to ppm displays then it makes complete sense to me for everyone to calculate their EC ratings as it's a scale we would all be able to compare against. Because otherwise if what you say is true and that it's not possible then everyone should throw away their tds pens and start using EC as it's again sounding like the only unit with some sense to it.

as an example if I was to start measuring shrimp in inches at least it's known to my buyer what inches can convert into. But buying shrimp with water parameters of a TDS@220 means little if we cant convert it to either EC (accepted unwavering standard) or to each others TDS ratings.

-edit-

oh and squiggles I edited my first post not knowing you had responded sorry, but please check the maths for me in my previous post.

I think you are over complicating it, the simple way for this to be solved is for the buyer to test the water their new shrimp come in with their own TDS pen & also slow acclimation is a definite necessity. I completely agree that we should probably use EC as a standard parameter but EC pens are not as freely available & definitely not as cheap as a TDS pen. Also, not everyone can afford a $100-$200 piece of equipment when a cheap $15 TDS pen will do the job. As with everything, what works for you may not work for someone else, I have crystal shrimp living in TDS values ranging from 150ppm to around 300ppm. I would not try the higher values with Taiwan Bees or Tigers but if people are buying $200-$500 shrimp then they will probably be able to afford a more adequate pen. No TDS pen or EC pen should ever need calibration but calibration is mainly used to initially set these instruments.

I can understand your confusion trying to work this out, having a single parameter that would make it a bit easier but I fear you will be trying to change what already works for a great majority of shrimp keepers around the world. :encouragement:

Well, very interesting and usefull topic.

At the early times of my hobby, I have serious issues with PPM metering and targeting. Changing my pens to EC meters helped me very much to be succesful breeding taiwan bees.

NIce

Iv been on here for about a year and a half and im only reading this for the first time lol very informative once again Marcus well done