I maintain a semi-public pool at my condo complex. There are a few things that are a little bit different when using TFP on a commercial pool.
1. For a private pool, you can decide your CYA level based on the amount of light you get, and then adjust your FC from there, according to the
CYA/Chlorine chart. With a commercial pool, you need to look at the maximum FC allowed by your local health code, then look down the "shock FC" column of the chart, and set your target CYA level from that. So if your pool ever gets slightly cloudy, you can boost the FC close to shock level without closing the pool. If your county health code has a maximum FC of 5ppm, you'll need to keep your CYA at 20ppm or lower, which means you need to get a
CYA test kit that can accurately measure that low.
2. Check your local health code's minimum Total Alkalinity. Mine is 80ppm, which is a pain, because higher TA means pH rises faster, which means I have to add more acid, which reduces TA as well as pH, which means I have to add more baking soda to raise TA, which means pH rises faster, which means I have to add more acid, and so on..... What's worse is that the inspectors use a test kit that works by color matching, not titration like the Taylor kit, and their test reads 20ppm lower than the Taylor. So I have to keep my TA at 100ppm, which gets even more expensive. Fortunately, if your TA is found to be a bit low, it's not an immediate closure thing. They just mark it as "needing to be corrected before the next inspection". Anyway, the goal is to keep your TA as low as your health code allows AND keeps your pH stable.
3. If you are currently using tablets for chlorination, and want to switch to liquid chlorine for the money savings and reduced need for water replacement, things are a bit more complicated than for a private pool. You'll need to file a "Plan Review" or permit application, which must be prepared by a "registered architect or registered professional engineer" licensed in your state. Then there's the plan review fee. Then you have to get a licensed professional to do the installation. Then the inspection of the completed work. All of which adds a good $750 or more above the cost of the actual chlorinating device. So you have to weigh the cost of replacing %40 of your water every year to reduce CYA with the cost of doing away with that problem permanently. Check with your inspector to see if you can switch chlorinating systems without having to do all the paperwork. Also, heat causes chlorine to lose its strength faster, so if your pump room gets hot like mine, you'll want to find a way to keep your liquid chlorine someplace cooler. (Tablets can handle heat no problem.)
4. Check your health code to see if "hand-feeding" of chlorine is allowed. Some areas let you kick people out of the pool for 15 minutes while you add chlorine; others require an automated system, and hand-feeding is allowed only in emergency. Of course, low FC in your pool could be called an emergency, so hand-feeding as a supplement to an automated system will likely be allowed. Ask your county inspector the next time he/she visits. Of course, if you're open 24/7, this probably isn't your preferred option.
5. Depending on your location, grocery-store bleach may be dramatically cheaper than more concentrated liquid chlorine, even if you buy the liquid in bulk. But there's still a fear among the uneducated that bleach isn't allowed. Look at the label of the bleach bottle and find the MSDS #. Then you can look that up and print out the master label for the product. The master label contains the labels for all the different approved packages for that chemical, including its use as a swimming pool sanitizer. If anyone questions the presence of bleach bottles in your pump room, show them the master label for your bleach, and how its use as a pool sanitizer is exactly the same as the 12.5% chlorine that happens to have that use listed directly on its bottle.
LEGAL DISCLAIMER: This is just a few opinions based on the experience of managing one semi-public pool for a couple years. It should not be construed as legal advice, and neither I nor this site can be held liable for any problems you run into with your local inspector.
Follow your local code carefully.
