[JB NY]

Originally posted by DaveJ
Interesting thread.... and I want to get input that I think others may find useful, as I would.

When y'all talk about stability, please define that as ranges per day.

Ca - +/- x ppm
Alk - +/- x dKH or ppm
Mg - +/- x ppm


Let me tell you why this is important for me... when I hear stable, that means steady consistent levels. Calcium runs 420 all the time for example. Or Alk is 9.5 all the time....

However, in our tanks, that constant value is almost impossible. Daily dosing say 70ml of Alk solution (two part) is to offset the .3 or .4 drop in dKH (15-20 ppm) per day. If you do that all at once, its not 'supposed' to be hard on critters. .5 is generally the acceptable daily change amount. However, by having to dose to adjust that level back up to your 'ideal' value, its by definition not stable.

See what I am getting at?? So please define stable and put some values attached to it.

First you need to understand that the test kits we use are not 100% accurate. A kit that costs under $50 is pretty good but I think that real labs use stuff that cost 10x what we pay. but mostly stable to me means that it is around the same. You should also get in the habit of testing around the same time. So if you test every day you should do it at the same time of day.

If had to give some +/- I would say

Alk +/- 0.5
Ca +/- 20
Mg +/- 30

Here are my records for about 1 1/2 years of taking monthly readings.

11/30/2003 Ca:430 Alk:10.2 Mg:1200
12/09/2003 Ca:420 Alk:10.2 Mg:1250
01/06/2004 Ca:415 Alk: 9.4  mg:1300  
02/06/2004 Ca:440 Alk: 8.6  Mg:1200 
02/17/2004 Ca:440 Alk: 8.4  mg:1350 
03/20/2004 Ca:470 Alk: 8.4  Mg:1320 
04/21/2004 Ca:460 Alk: 8.6  Mg:1350 
06/23/2004 Ca:490 Alk: 7.7  Mg:1320 
07/28/2004 Ca:470 Alk: 8.6  mg:1350 
09/03/2004 Ca:480 Alk: 10.9 Mg:1390 
10/07/2004 Ca:480 Alk: 10.6 Mg:1390  
11/03/2004 Ca:550 Alk: 9.6  mg:1350
12/08/2004 Ca:470 Alk: 8.4  Mg:1320
02/06/2005 Ca:470 Alk: 7.7  Mg:1320

I started keeping my alk lower and Ca higher in Dec 2003. The spike in sept 2004 is from being lazy for the summer. But no problems happened because of it.