Kalkwasser going bad in reactor? - Page 2

jccaclimber · 11/06/2017, 10:19 PM

City provided water in Murphy (Dallas), TX. Surface lakes are the local source. It's also worth noting that at the time I was changing 300 gallons of fresh water in another tank every 1-3 weeks, so "quickly" was probably 600-1000 gallons of RO/DI. On the other systems I deal with that would be many months worth, so it may just be a function of throughput. Really I should probably have a DI for the reef and non DI for the planted tank, but that's more containers and a separate discussion.

Is there something about low TDS water that makes pH probes (or less accurately bromothymol blue) inaccurate?

bertoni · 11/07/2017, 01:23 PM

I'm not sure how much carbon dioxide would be in your water. You could take a small sample, measure the pH, and then aerate it for a few hours outside. If the pH rises much, then I'd suspect there's a lot of carbon dioxide in the water.

pH meters don't work in RO/DI. Even RO might be suspect. One problem is the lack of buffering, which means that the pH can shift quickly, and possibly even be influenced by the probe itself. That's why the pH test kits are unreliable. I don't know the details. We could look up some reading, if you're interested.

11/07/2017, 01:23 PM	#27
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I'm not sure how much carbon dioxide would be in your water. You could take a small sample, measure the pH, and then aerate it for a few hours outside. If the pH rises much, then I'd suspect there's a lot of carbon dioxide in the water. pH meters don't work in RO/DI. Even RO might be suspect. One problem is the lack of buffering, which means that the pH can shift quickly, and possibly even be influenced by the probe itself. That's why the pH test kits are unreliable. I don't know the details. We could look up some reading, if you're interested. __________________ Jonathan Bertoni

11/06/2017, 10:19 PM	#26
jccaclimber Registered Member Join Date: May 2013 Location: San Francisco, CA Posts: 528	City provided water in Murphy (Dallas), TX. Surface lakes are the local source. It's also worth noting that at the time I was changing 300 gallons of fresh water in another tank every 1-3 weeks, so "quickly" was probably 600-1000 gallons of RO/DI. On the other systems I deal with that would be many months worth, so it may just be a function of throughput. Really I should probably have a DI for the reef and non DI for the planted tank, but that's more containers and a separate discussion. Is there something about low TDS water that makes pH probes (or less accurately bromothymol blue) inaccurate?