Have you ever tried doing research on water conditioners, algae controllers, or other aquarium water additives and found warnings that none of them are safe for your turtles? These warnings are very surprising to see about such common products that can be found in any pet store; including Tetra AquaSafe, Zoo Med Reptisafe, API Water Conditioner, Quick Start and all other common additives. The warnings will claim that the chemicals in the additives are toxic and can be harmful to the eyes and lungs of turtles. You may be skeptical, but the degree to which these chemicals are condemned is probably enough for you to err on the side of caution.
However, this is problematic if the healthiest option for your reptile is to use the particular conditioner you were looking into. And to skip right to the punch, I don't see the evidence for these products being harmful.
Before I proceed, please note that I am not an expert. However, the warnings I have read online are not given by experts either. Yet, I would expect that experts did formulate these readily available water treatments to be safe products when used for the purposes intended, in the amounts and concentration instructed.
In general, I would recommend not using any additives unless there is a clear benefit or otherwise important purpose for doing so. However, in many cases, using water conditioner or other products is the most practical way of keeping your tank water safe or in check.
As an example, if you have chlorine in your tap water, you need to remove it somehow to make it safe for your aquarium inhabitants. In this case, you have three main options for being able to add safe water to your aquarium. You can fill containers with tap water and let them sit for an extended period of time so the chlorine can evaporate from the water before adding it. This is inherently problematic because it takes time and planning that most people would be unwilling to do regularly. Further, it's unclear when the water is chlorine free and could be added in too soon.
A second option is to buy water from a store for your aquarium. Both options get more and more impractical the larger your aquarium is.
The most practical solution is to simply add a water conditioner as you replace tank water with new tap water. Given that it might cost a lot of money, time and effort to safely do water changes with the first two options, it is a dangerous idea to tell keepers that the third option is unsafe.
A general note on toxicity
All of the minimally supported claims I have seen about the toxicity of any conditioner product are made about the dangers of any number of particular chemicals in these products. Usually, the only support given is references to Material Safety Data Sheets (MSDSs) which may describe a certain component as some kind of irritant or list other safety precautions. This information alone is inappropriately taken to conclude that the product as a whole is unsafe.
These MSDSs exist partly to provide information about the hazards (if any) to humans that may be of concern in instances of misuse. So toxicity and hazards are usually reported in the context of its effects on humans. Further, specific reports of ingredient toxicity refers to exposure to the ingredient at 100% concentration and a specific amount of exposure. When animal toxicity data is available for an ingredient, it may be provided in the amount that is toxic to a rat. The amount is usually very high, such as in excess of one gram. It must be kept in mind that these active ingredients of aquarium additives are usually measured in micrograms present in one dose or treatment. For example, a dose of water conditioner may be 10mL which may contain only micrograms of the ingredient, which is then further diluted into 10 gallons of water. There is just enough for the additive to do its job, but the concentration of ingredients that may be considered irritants are so diluted that they are not even remotely toxic to turtles.
Concentration is critical to consider. It is not necessarily the case that a given ingredient itself is toxic. It is far more likely that the ingredient becomes toxic at a certain concentration or amount. If you take table salt for instance, sodium is a critical electrolyte for your body, and we need sodium to function properly. You put a little bit of salt on your dinner, because it makes your food taste better. However, you wouldn't eat a tablespoon of salt because besides tasting horrible, it becomes toxic in such a large amount.
Real life usage
Empirically, I have used many of the aquarium additives and conditioners in my turtle and fish aquariums. I have never noticed any behavioral or health changes or signs of eye irritation as a result of adding these products to the tank water. Not to mention the thousands of keepers who also use these products. If these products are unsafe, how have issues not been linked to these products? If they caused any health issues, I would expect that it would be quickly traced to the product and it would force a recall and product discontinuation.
Another thing to consider is that fish can be an indicator of water quality issues. Most, if not all additives branded for use in turtle tanks can be used in aquariums with fish too. Even additives branded just for fish usually contain the same active ingredients. Physiologies are, of course, not the same between fish and turtles. However, if additives did introduce a harmful chemical (or harmful concentration) you would expect to see that translate to health problems or signs of irritation in your fish long before it would effect a turtle. Similar to how if you have an ammonia spike, your fish might not survive, but your turtles may still be acting completely normal. To reiterate, if the additive doesn't bother your fish, it’s even less likely that it bothers your turtle.
Invisible problems
It might be argued that just because additives don't cause noticeable health problems doesn't mean that they are healthy for your turtles. This is a reasonable position to take, and having a healthy skepticism towards what you expose your pets to is probably a good idea.
The reality is that there have not been studies to find out for instance if long term additive usage effects the longevity of turtles. Let me emphasize that a lack of such evidence doesn't mean it should be assumed that there is any long term detriments whatsoever. Instead, I will return to my earlier suggestion: if you can safely and easily avoid using additives, you should. But if not using additives may result in exposing your turtles to definite known hazards such as chlorine, then it's not worth avoiding on the slim chance that additives pose any risk factor.
Take home points:
- There is no evidence that aquarium water additive ingredients are harmful to fish or turtles at the concentration in the products when following the directions
- Ingredients in water conditioner or other additives may be irritants at high concentrations or large amounts but this does not translate to extremely low concentrations
- If you don't need to use any kind of conditioner-don't
- In some cases, avoiding using conditioners can do more harm than good
- If you need to remove chlorine or balance your aquarium water in other ways, you should use the appropriate aquarium conditioner as directed
- Always mix conditioner in a minimum of 1 gallon of water to avoiding dosing more than necessary