D.I. tanks marked at 200k

[jbed]

Can anyone help me with this one?

I am getting all of my water from a pair of Culligan D.I. tanks that are marked at 200k. Culligan tells me this will give me something less than 5 meg/l....

1. Is this correct?

2. Is this sufficient for my sw tank.

p.s. I have a thread going in general discussion and lighting/equipment that explains the problems I am having in greater detail. (thread : "help w losing inverts")

Thanks in advance!

[Randy Holmes-Farley]

I don't know what "marked at 200k" means. Can you elaborate?

[jbed]

Apparently culligan rates their tanks by this means. I think it is the conductivity of what comes out of the tanks. I can call them again and try to have him explain this to me, but the last time he did it was so over my head it didn't do much good.

Also, I just read your article on Iron dosing and Caulerpa problems. This happened in my refugium just a few months ago as well. My Caulerpa was doing great, and then it started to thin out to eventually nothing. Now I can't get it re-established, and the micro in my tank is taking over everything.

In the other threads I have been advised to do large water changes, but I am trying to verify that the d.i. water I am using is not a part of my problems before I do the water changes.

[Randy Holmes-Farley]

Yes a little more info from Culligan might solve the confusion.

It is unlikely that the nature of the water caused the Caulerpa issue, IMO. I'm also not sure what a water change is trying to cure.

[seven ephors]

it is 200 kilo-ohm/cm of resistivity. Good DI water is anywhere between ~18 megaohm to 2 megaohm. 1 megaohm is 1 meq/l, or 1 uS.

[jbed]

OK, just got off the phone with David at the local Culligan shop.

There are two D.I. tanks, both marked with 200k on them on a quality rating sticker. Then there is a light on the output from the tanks that is marked 20k. The light is on a conductivity meter (not resistivity according to culligan - it is not that pure).

The light is there to measure when the quality of the water falls below 20,000 ohm conductivity (then the light goes out telling you the tanks need to be recharged.)

According to culligan, 20,000 ohm of conductivity is equal to 15 ppm tds, or 15 mg/l. Therefore, I am getting water that measures under 15 ppm tds (don't know how much under 15 until I get my tds meter in) until the light goes out.

15 ppm sounds high for D.I. water in a reef tank.

Does this info help any??

Thanks again!

[Randy Holmes-Farley]

15 ppm is very high for DI water, but it is probably OK use.

[Boomer]

Here is a table for you

http://www.omega.com/techref/ph-2.html


.023 megaohms = 23,000 ohms= 17-20ppm

There 20,000 =15 ppm is a little low, it is more like in the 30,000 for 15 ppm. 20,000 = >30 ppm

Of course all this can vary somewhat, depending on what they are calibrating the meter with, KCl, NaCl, etc..

[Randy Holmes-Farley]

Thanks, Boomer. :)

jbed:

FWIW, it isn't really conductivity per se that we care about in assessing water suitability.

It is what is in it that we really care about. 1,000 ppm would be OK if it were comprised of just sodium and chloride, but 0.1 ppm would be too much if it were copper chloride.

One of the big concerns is that the EPA allows up to 1.2 ppm copper in drinking water in the US, while a reef aquarium needs far less. So if it has exposure to copper pipes, etc, then it might not be OK.

[seven ephors]

>...Then there is a light on the output from the tanks that is marked 20k. The light is on a conductivity meter (not resistivity according to culligan - it is not that pure).

It is funny that they use resistivity unit (ohm) for conductivity. I guess engineers and trade people do that all the time :roll:

[jbed]

Just got my TDS meter today and tested the D.I. water.

Tested at 9 ppm.

That I would think is acceptable, now I guess I just have to find out if the copper in my tank (.05 mg/l) is coming from my D.I. system.

Does anyone know if the fasTesT saltwater copper test can be used to test my fresh D.I. water?

[Randy Holmes-Farley]

I do not know for sure, but I'd expect that copper kits work OK in freshwater.