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Re: Cleaning Glass

Bob Dixon wrote:
> Okay, so your chemistry is a little sharper than mine, but ow come I can get 
> the stuff off the underside of my cover?  How come the rest of us aren't 
> experiencing this "redeposited glass" thing?  What's so different about 
> Mississippi water that you are seeing this and I'm not?

Most of the deposits that I see on -my- glass surfaces is caused by
splashes of one type or another causing deposits of the minerals that I
dissolve in my aquarium water. I think Paul is not experiencing the
splashing phenomena; indeed, if he left a little carbonate deposit on
the glass, maybe the pure H2O being left by condensation wouldn't etch
the glass as much. I think Paul experiences this more than other folks
because he has a high temperature gradient in the tanks at night; the
room temperature drops rapidly after the sun goes down and these tanks
of warm water are going to condense water on the glass which is
essentially at the current ambient temperature. If Paul had a supply of
free, cold water, I suppose he could run some low flow rate tubes
through the bottoms of the tanks to cool the water to a lower than
ambient temp. This would make it easier to maintain the daphnia species
too. Keeping those tanks at 90F must be a problem. I think Paul is also
taking advantage of sunlight although he did say he had aquarium lights
sitting on the glass.

Indeed there might be some really easy way to implement a passive
cooling system. What if he got the electricity for free at his place of
work? Maybe all it would take is a good room fan and a try of water for
the tanks to sit in. Unsealing the tanks would work too however I know
that Paul depends upon the covers to keep in the CO2 from his poor man's
CO2 system. [Paul will tell you about the garbage bag method now or you
can look it up in the archives; you newbies and starving students should
learn about that cool trick]

I suspect that its just pure H2O that's doing the etching. The only
thing that could make it more caustic would be if there were some
noxious fumes that formed nitric acid. Somehow that sounds like more of
an LA smog phenomenon although maybe his lab is in the chemistry
building. I recall some very awful chemistry building smells from my
alma mater days. You're not a smoker, are you Paul? I can almost picture
an old briar stuck in the bulging pockets of the old corduroy jacket
with the leather elbow patches! ;-)

> The carbonate buildup in a pot that is used to boil water is not soft, it is 
> rock hard.  Maybe your lights are baking the stuff on?  I'd still try the 
> CLR, and if it comes off, it is carbonates.

But if it doesn't dissolve in hydrochloric acid, then its not
carbonates. Paul said he gave it the acid test. I have to respect Paul's
scientific method. Even vinegar will work to dissolve lime deposits,
with a little elbow grease. I have some HCl but even I'm not crazy
enough to try using that to clean my glass covers. (sorry Paul, didn't
mean to imply anything with that remark ;-)

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!