HTH is a calcium based product, which means that although it can be very effective in killing off contaminants in your water, it can also lead to some problems long-term. The high level of chlorine in HTH can more rapidly bleach out liners and bathing suits then other chlorine products. Also, with long-term, high usage of HTH, the pool can develop calcium buildup, which would lead to calcium scaling inside of the filter and in the lines of the pool. This scaling ultimately causes damage to your filtration system, and can be avoided by using HTH in limited amounts, or by using other types of chlorines.