Okay, so I have been looking into this for a bit. In my experience, I have only ever used the Hydrochloric Acid otherwise known as Muriatic Acid. The only time I have ever been around Sulfuric Acid was in high school chemistry. I have worked as a pool builder for almost ten years now and worked on the pool service side of things for a year. In that time I have used Muriatic Acid, quite a bit and never once used sulfuric acid. I worked for a company and we just never used anything other than Muriatic Acid for lowering the pH in a pool. Honestly, I didn’t know that you could use Sulfuric Acid. In my research, I have found out a few things regarding the differences between the two types of acids. This post will be for those of you who are wondering which type of acid to use in your pool. Reading this post will also save you time in your research, because I have done that for you and will give you the overall results of my findings. If you have anything to add to this topic, please do so. The more information we get the better.
To start off, I want to say that both Muriatic Acid and Sulfuric Acid will lower the pH in your pool. Through everything I have read related to this topic, the general consensus is that they both work for this application. There are, however, some differences that I feel you should know about. It seems as though the most used type of acid for swimming pools is the Muriatic Acid. This is also the most suggested type of acid to use. There are some positives and negatives that should be addressed. One is that Muriatic Acid will lower the pH of your pool without any additional side effects to the water. It is also fairly inexpensive and easy to come by. I have also read that COSHH regulations (Control Of Substances Hazardous to Health) place responsibility on employers to use the least hazardous chemical to achieve satisfactory performance. This could be why I have never used Sulfuric Acid in the past. Muriatic Acid is less harmful than Sulfuric Acid. Knowing that Sulfuric Acid can leave severe burns on your skin is almost common sense these days. I have never been burned by Sulfuric Acid before, but I can tell you that I have had Muriatic acid on my skin and received no burns. I did, however, get a weird tingly feeling on my arms and hands where they were exposed to the acid, but after I rinsed it off with water the sensation subsided. I have also read that Muriatic Acid creates more fumes than Sulfuric Acid, and those fumes can be hazardous to plant life and pool equipment. I don’t doubt that at all. I have taken in a big whiff of those fumes and, take it from me, it’s not something you want to breath in. If stored in a “pool equipment room” where there will be little to no ventilation then the fumes can cause components of the equipment to corrode. It also seems as though the fumes can kill pool side plants.
There are also some things you should know about using Sulfuric Acid in your pool. While it will lower the pH in the pool, it will also increase the total dissolved solids in the water, and add unnecessary sulfates to the water. These sulfates can increase the possibility of stainless steel corrosion and if the acid combines with calcium ions it can be very difficult to remove. In order to keep the sulfates at a minimum, you will likely have to dilute the pool water. In addition to all that, it is my understanding that there are varying strengths of sulfuric acid and you will want to make sure you get the correct one. You will also want to be very careful when using this type of acid. As I have said before, it can cause severe burns to living tissue. One benefit would be that this type of acid does not fume as much as Muriatic Acid. So, Sulfuric Acid would be less likely to corrode equipment in your pool equipment rooms.
Overall, I think that the majority of people would recommend using Muriatic Acid in swimming pools for a few reasons. First, it is safer to use. Second, it does the same job but without added side effects to the water, and third, it tends to be more readily available to consumers. Regardless of which you use, it is important to understand that both of these chemicals can be dangerous and should be treated with care when using them. So, there you have it. If you have any comments, questions, or concerns feel free to post them and I will do my best to address them.