rusticitas

I have one of Oakton's TDSTestrs and I am starting to get strange results... I think. It seems to "drift" on readings. The longer I leave it in a tank, it slowly creeps up or down in value. I am thinking I should get a calibration solution to test this, and also to calibrate.

I have been looking over the Oakton web site, about their
but I have NO idea what I am looking for? Their ECTestr and TDSTestr seem very similar-ish, and I vaguely understand that there is a relationship between EC and TDS, and that TDS can be read as microsiemens or ppm.

I am confused. Which TDS test solution should I get? It seems that getting a solution is much simpler than the packets (to save mixing, and especially errors in mixing!). They have the following solutions available (in microsiemens): 12880, 1500, 84, 1413, 2764, 23, 2070, 80, 447, 15000 and 8974.

-Jason

rusticitas

Never fails, I ask the question, then I figure out the answer...

Just FYI for anyone else that might have had the same, here is what I found:

http://www.4oakton.com/Con_to_TDS.htm
and
http://www.hydroponicequipment.com/infopages/tds.shtml

If I understand correctly -- and this is just a quick and dirty reading, so more assumption than fact -- that the TDS values best associated with aquaria would be a "442" solution, which for my tap water (which is quite nearly effectively RO), the closest solution to what I keep my tanks at using Seachem Equilibrium is about ~500 ppm, and there is a test solution of 447 µs (microsiemens) which translates to ~300 ppm TDS.

This might not be very clear explanation, but I am writing this as I am learning it. I would greatly welcome comments and corrections!

Thanks.



-Jason

P.S. Is there a way to correlate GH in ppm or dH using a TDS meter? Since my tap water is virtually empty (like "virtual" RO water), with pH ~7.0, and I add in Equilibrium, is there a way to correlate a "true" GH reading using the TDS meter?

yxberia

I think pure RO water has TDS of 0 ppm reading. Is it a good idea to use RO for calibration ?

I don't think TDS can tell any information about GH. As TDS meter measures both cation and anion plus other organic ion.