Q: I’ve been battling hair algae in my tank for months, and I can’t seem to beat it no matter how much of the stuff I pull out, what herbivores I add, or how often I change water to lower the nutrient levels. So, I’m considering dosing [a proprietary additive for eliminating algae] to help bring the problem under control.
To find out what other hobbyists are saying about the effectiveness of this product, I’ve been reading comments both on the manufacturer’s website and hobby forums. However, this research has been of little help because the comments range anywhere from “This is a miracle product” to “This product is snake oil.” Also, some claim it had no effect on their livestock whatsoever while others claim it killed certain animals or even caused a complete wipeout. How can people have such wildly different experiences with the same product?
A: Thanks for your question, Bethany! Your experience in researching this product highlights how unreliable hobbyist anecdotes can be. There are several reasons hobbyists can have very different experiences with the same product (or claim to) and, thus, write such divergent comments on websites and forums. Examples, in no particular order, include the following. (Note that these can be applied to many different aquarium products or additives, not just the one you mention in your question. Also note that I have no firsthand experience with the product you’re researching, so I won’t attempt to review it or rate its efficacy here.)
When reading comments about any aquarium product, it’s often helpful to disregard the most glowing compliments and the harshest critiques. The reason being, there’s always a possibility that the former are posted by an individual with a vested interest in the product’s success (e.g. the manufacturer, a friend or family member, or someone otherwise affiliated with the company), and that the latter are posted by a competitor or someone with an axe to grind. Focus instead on the bulk of comments that fall somewhere between these two extremes.
Varying problem severity
Two hobbyists fighting the same issue might get very different results from a product depending on the severity of their respective problems. You probably won’t see much benefit from the type of product you’re researching in a generally neglected system that is choked with algae and has sky-high nitrate and phosphate levels. On the other hand, assuming the product is actually efficacious, you might see some benefit in a generally well-maintained system that just needs a little nudge to create an environment less favorable to algal growth.
Varying product quality
Results may also vary because products can be subjected to very different treatment or conditions between the time they leave the manufacturing facility and the time they’re actually added to an aquarium system. For example, a product that is efficacious when handled properly may be rendered useless when exposed to temperature extremes, left in storage for an unacceptably long period, or otherwise exposed to conditions that degrade its quality.
The effectiveness of any given aquarium additive depends on proper use and dosing as specified by the manufacturer. Hobbyists who are careless when it comes to measurement conversions, or are of the mindset that “If a little is good, more is better,” will likely over- or underdose the product and get subpar results as a consequence.
Post hoc ergo propter hoc fallacy
This well-known logical fallacy assumes that because an event occurred first, it must be the cause of an event that occurred later. Post hoc is often in play when we draw conclusions about the effectiveness of an aquarium additive. For example, a hobbyist might add the latest, greatest proprietary algae-control product, see the algae dissipate in the ensuing weeks or months, and then credit the product for getting rid of the algae when, in fact, the algal bloom may have waned on its own with no help from the aquarist because the nutrients fueling it were getting exhausted. On the other hand, a hobbyist might blame an additive for livestock losses that occurred subsequent to dosing when the real culprit was some other factor, such as an ammonia spike, and the timing was merely coincidental.