Thanks Dave, yes I read this on the container, albeit by straining.

Its a general concern. I just started using the RO/DI water. For one thing
I can't measure my GH with my current test kit, none registers. I am using
pretty much exactly what you are using, and same water change routine. Also
a *touch* of sodium bicarbonate, enough to make my KH 3-4.

Believe me, I'd much rather I had useable tap-water.

thanks,

bob



"Dave Millman" wrote in message
...
Bob A wrote:

One other question, since I'm now using RO/DI water, and RO Right, the
RO
Right does not register on my GH test. The (TINY) instructions on the
packaging say that typically GH tests measure Ca and apparently there
isn't
much in RO Right.

How important is Ca in an aquarium, both to the fish and to the plants?

For a complete label printout, go to:

http://www.kentmarine.com/ror.html

Key quote:

"General hardness or GH tests usually only measure calcium & magnesium
content
and are a poor substitute. Do not greatly exceed the recommended teaspoons
even
if your test indicates different!"

I use pure reconstituted RO water in my tank (no tap water). I use one
teaspoon
per 10 gallons of change water for a 30% weekly change. My plants show no
signs
of calcium deficiency. Snail and shrimp shells do fine too.

Do you have actual indications of a calcium deficiency, or is this a
general
concern?