Do we truly understand the interactive risk and contradictions we might be creating for our customers to swim in? If you depend on product labeling, SDS sheets, EPA registration or NSF listings for this information, think again. There are some potentially hazardous chemical combinations you might not be aware of.
It is highly likely that, without warning labels or proper education, professionals are creating combinations that are unsafe, harmful, or at a minimum contradictive. The EPA, NSF, and current labeling laws do not mandate disclosure of interactive risk with other known additives in pool water. But if you combine certain chemicals, the byproduct reactions become your professional responsibility.
Last September, NSF released an addendum to standard 50 to specifically address recreational water. The new language accounts for the fact that professionals continually manage the same body of water with the regular addition of chemicals, as well as the fact that these chemicals can have a cumulative toxicology impact. But interactive risks are not considered. For now, it is up to pool professionals to seek the information necessary to determine these risks. Let’s explore some possible candidates for reconsideration.
When adding chemicals to any pool, technicians should follow two crucial steps. The first is to operate the pump, unless instructed otherwise on the packaging. The second is to circulate the water to ensure proper mixing and dilution.
Secondly, always add chemicals at different locations in the pool to avoid the risk of chemical conflict or harmful reactions. For example, acid should never be poured on top of chlorine. The combination could produce chlorine gas, a dangerous byproduct that irritates mucous membranes, causes breathing difficulty and irritates the skin. A common problem involves the use of an inline chlorinator and/or a floater that stores trichlor tablets. Never mix trichlor tablets and any concentration of cal hypo chlorine or bleach, as this will create a dangerous reaction. Cal hypo also comes in a tablet form for erosion feeders, so you must be careful never to mix cal hypo tablets and trichlor tablets with their respective feeders.
Next, when adjusting alkalinity with sodium bicarbonate, always do this before adjusting the pH with acid. Acid and sodium bicarbonate (or bicarb) accomplish opposite goals. Bicarb raises alkalinity and pH, while acid drives these readings down. If you pour both chemicals in the same location, the acid can destroy alkalinity and defeat your chemical goal.
Another practice that is often overlooked is diluting muriatic acid before adding it to the water. By doing this, you are raising the pH of the acid, which reduces its alkalinity-lowering impact. The goal of diluting the acid while trying to adjust the pH and alkalinity of your water is to reduce the use of bicarb and acid. Maintaining a higher alkalinity will help balance and keep your pH from fluctuating and stay away from the constant seesaw of high pH and low alkalinity and vice versa.
The use of some sequestering agents or stain/metal control products is common. Many contain phosphoric acid for stain protection, even though the label or SDS sheet will not always say so. Obviously using a phosphate-based sequestering agent in conjunction with a phosphate remover is counterproductive. But it is common for builders to add sequestering agents at start-up, only to have the service technician test for phosphate and treat the pool to remove it. Once the phosphate remover is added, it will diminish the sequestering agent’s effectiveness at startup. Consult the manufacturer to determine if there is a conflict.
Another potential conflict relates to “drought-sensitive products” that leave liquid chemical films on the water’s surface to reduce evaporation or contain heat. Most are carbon chain films, which may increase sanitizer demand. Their SDS sheets specifically say to avoid oxidizing materials. Also, using clarifiers, non-chlorine shock, and enzyme products may cause contradiction by coagulating or destroying the product.
The final subject of contradiction involves the use of bromine-based chemicals versus chlorine-based. I am sure you have all heard that it is possible to turn a chlorine pool into a bromine pool, but not the other way around. This is because when you add chlorine to a bromine pool it converts the bromide (used up bromine) back into free bromine. When you add bromine to a chlorine pool, on the other hand, the bromine does not go away but builds up over time, creating a chlorine demand. Therefore, when you shock the pool with chlorine, the residual bromine will convert the chlorine into, you guessed it, bromine. So when professionals test the water, it will indicate that there’s no chlorine, when there’s actually bromine.
Check your SDS sheets to determine if the products you are using contain such properties.
The contents of many chemicals are obscured, so labeling may not blatantly say it is bromine. However, it is common to find the word “yellow” in the description of bromine-based chemicals. This may help you see when bromine is in a product.
The underlying chemical and trade name require evaluation. Commonly, the use of “trade secret” when describing a product’s chemical content makes it more difficult to evaluate the true chemical or combination you are utilizing. In these cases the SDS sheet can be helpful.
As with the use and handling of all chemicals, proper respiratory and protective gear goggles, gloves, clothing, and approved masks should be used at all times.
It is federal law that you possess the SDS sheets of all chemicals in your truck or store, so make sure all employees understand this federal requirement and always have access to them for inspection. Having this documentation at another location will not comply with DOT and EPA requirements.
The goal of this article is to challenge professionals and the buying public to explore the interactive risks and contradictions of commonly used chemicals in the pool industry. In the future, it is possible that labels will be required to contain such information and that NSF and EPA standards will begin to address these common occurrences and risks.