re: Scales and Balances

["Rachel Sandage" <rachelsor at hotmail_com>]

James Purchase is thinking about getting precise with his dosing, and 
wondering whether he needs sensitivity to .1 or .01 grams. Ghazanfar Ghori 
pointed out that the chemical composition of the water coming out of the tap 
is already pretty variable (assuming you are not using reconstituted r/o 
water or something like that).

I have two more questions:
1. Do you know how much water is in your tank? I sure don't. My plant tank 
is nominally 72 gallons, but I doubt if it would hold that much empty. There 
is also the space taken up by substrate, driftwood, plants, and fish. I 
guess you could fill the tank up gallon by gallon, or use some sort of 
metered delivery system to find out, but that seems like an awful lot of 
work in any tank larger than 10 gallons or so. So there may be a fair amount 
of uncertainty there.

2. Just for fun, I went over to Chuck Gadd's dosage calculator. I assumed a 
50 gallon tank, and set the amount of water to mix with to 1ml of water, so 
that I could see what the difference would be if I tossed the whole amount 
in at once. The difference between using 1.10g KNO3 and 1.19g KNO3 is .26 
ppm in a 50 gallon tank. Given the small size of that difference, I would 
think that the .1 resolution would probably work well, unless the tank were 
really, really small.

-Rachel



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