Update: Spreadsheet Changed To Account For Earlier Discrepancies
While cruising the internet I noticed an online water change calculator (TheAquaTools.com) that predicted how various chemical levels (nitrate, phosphate, etc.) in the aquarium would change in response to a new water change schedule. I very much liked the concept and admired the fact that it represented an improvement on some of my own formulas. No less, I also noticed a few fallacies in the aforementioned calculator and noted that its abilities were a little limited. Consequently, I just had to build my own to see if I could do better, and I think that I succeeded in this aim. My version of the water change calculator is below (see attachment).
The original water change calculator was very well-designed, simple, and effective. I, no less, am never simple, never pause for design, and do not stop at effectiveness: I thus had to tinker with the concept. In using the online version, I noticed the following limitations:
These limitations are part of the nature of the beast in that simple models that are easy to create (and use) are often just that--simple. They do not account for many details and thus are going to have implicit constraints that really cannot be overcome unless the model itself is extended. This is the approach that I chose, I expanded the fundamental model. Nonetheless, I have to admit with a certain embarrassment that the creator of that online calculator did point out a major flaw in some of my own computations: I have not addressed the incoming water as a source of waste until I saw it being done in that online calculator. Heretofore, I have only been concerned with what the aquarium produces itself, but some contaminants, like nitrate and ammonia, are sometimes found in the water source in addition to being an effect of biological processes.
I had to rethink my fundamental recursive equations.
My version, concisely, addresses the issues I noticed in the original. More specifically, my spreadsheet version has the following features:
How well I did in creating a "better mousetrap" is something that I will leave in the users' hands. I look forward to the various ideas people will send my way as a result of this new spreadsheet concept.
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