Chlorine Tablets in the skimmer

[chem geek]

David,

Except for tablets specifically designed to go into the skimmer (e.g. BioGuard Smart Sticks), regular Trichlor tablets should not be put into the skimmer. The acidity is very high (pH is very low) and can harm the area around the skimmer, not just the pump when the water is turned on. I actually did that once and had my pool thermometer corrode so it doesn't take that long. Pool builders report not only that heaters and pump seals are damaged, but the plaster area around the skimmer gets pitted or weakened as well.

A single tablet of Trichlor in the skimmer may not be enough to cause serious damage, but repeated use could cause serious cumulative damage. Each blast of acid strips away a little metal or weakens pump seals each time, so that's at least once every day depending on how many pump cycles you have per day. It may also be that the acidity slowly diffuses up the pipe. An 8-ounce Trichlor puck that takes 5 days to dissolve in a floating feeder (that's my experience) would after 16 hours of pump off-time have 13% of it dissolve. The amount of water in a 1.5" diameter pipe that is 100 feet long is 1.2 cubic feet or only 9 gallons so that partial tablet would result in a pH of 4 if it dissolved in the volume of that pipe.

Even having tablets in a floating feeder can be a problem if it "parks" itself in one place. I partially rusted some stainless steel mounts in my pool that were closest to where my Trichlor feeder parked itself (this was before I looked into pool water chemistry and switched to using chlorinating liquid).

Of course, far worse would be pouring Muriatic Acid into the skimmer -- that's a longer exposure and far lower pH no matter how slowly you try and pour it (unless you use an eyedropper!).

Richard