Help with appropriate shock for vinyl in-ground

[PoolDoc]

3. Lastly, I still don't quite understand (or maybe it's more a matter of confidence in my understanding) the recommended daily chlorine levels. A regular level of 5-10ppm just seems awfully high based on what I'm being told elsewhere. My pool store recommends keeping it around 3ppm and my test kit says to keep it between 2-4ppm. In fact, the range on my color chart only goes to 5ppm. What am I missing? Is it because the BBB method corrects for CYA? Assuming that my Leslie's DPD kit is appropriate, how do you even determine a chlorine level >5?

I'll answer the easy bit, first. Use the Amazon page (linked in my signature) and order the K1515 which adds only the DPD-FAS chlorine test. I think Leslie's kit is a private label K2005, so when you add the K1515, you have a K2006.

Ok, the harder bit.

Yeah, we tell people to maintain MUCH higher levels than the various standards and labels do. But here are some facts to consider:

#1 - When I first started recommending higher chlorine levels than the rest of the pool industry, way back in 1996 with PoolSolutions, 2 things were true:
(a) EVERYBODY in the pool industry, including the US EPA was saying 3 ppm was the absolute maximum chlorine level in swimming pools, BUT
(b) At that same point in time, the Federal potable water standards --- set by the US EPA -- had NO upper limit on chlorine in DRINKING water.

The result? People filled pools with water that -- according to the EPA -- was safe to drink, but that wasn't -- according to the EPA -- safe to swim in, till the chlorine levels (sometimes > 5 ppm!) dropped. You could drink it, cook with it, and bathe your baby in it . . . but not swim in it.

#2 - More recently, the US EPA has revised drinking water rules to include a 4 ppm "action level" on chlorine in drinking water. This means if your local water company accidentally overfeeds chlorine, and finds they are shipping water with 10 ppm FC, they have to take "action" to correct the over feed. BUT, the required action does NOT include having to tell their customers that they may -- right now -- be filling their pools with water that has too much chlorine to swim in.

#3 - But, the fact is, 5 ppm is unnecessarily high in pools . . . if you have no stabilizer. Chlorine levels that high in unstabilized indoor pools seem to serve no useful purpose, and they ARE slightly more irritating (absent stabilizer) than lower levels are.

#4 - HOWEVER, we don't recommend levels above 5 for unstabilized pools -- please read the Best Guess page linked in my signature below. Rather, we recommend increasingly high chlorine levels as stabilizer levels go up. Why? Because stabilized chlorine is essentially chlorine "in reserve" -- it's available to be "called up for active duty", but until the small fraction of chlorine in a stabilized pool that IS on "active duty" is consumed, the rest of the chlorine remains largely inactive.

So, the bottom line is, 20 ppm FC in a stabilized pool is more like 1 ppm FC in an unstabilized pool, than it is like 3 ppm in a stabilized pool.

#5 - What's more, the national pool organizations (NSPF, NSPI => APSP, and even the CDC) are have gradually recognized what we've been saying here. They haven't quite caught up, but they are moving in that direction. Maybe in another 15 years, they'll agree with us!

#6 - The EPA, and chlorine product labels, are another matter. These labels are regulated under a very cumbersome Federal Act, generally referred to as FIFRA. A very elaborate and expensive process is required to change these labels even trivially. A change in safety guidelines is worse. And, the cost is borne by the product manufacturer. However, they have NO incentive to spend that money, for an extremely simple reason: you, and millions of other pool owners, will use LESS chlorine, if they fix the labels -- so people maintain higher levels of chlorine -- than if they leave them alone, resulting in people continuing to maintain inadequate levels of chlorine.

So they are faced with the reality that, if they spend money to FIX the labels, they will LOSE money in sales and profits as a direct result. Thanks to current rules regulating publicly owned companies, they could even be sued by stockholders for acting in a manner that decreased stockholder assets and earnings!

#7 - It's very popular these days in the MSM to talk about, or report on, the dangers of chlorine. (Actually it may have slacked off a bit from a couple of years ago). But, the research that underlies most of these idiotic reports -- and there is some genuine research -- is most often about 1 of 2 things. Either it is reasearch into the LONG-TERM (50+ year) effects of "DBPs" (Disinfection , ie chlorination, By Products) in drinking water. Or, it is on the effects of DBPs or "THMs"( Tri-Halo-Methanes, a particular class of DBPs) on users of INDOOR pools. There *is* something to this research, especially the indoor pool effects. But what you have to keep in mind is that the implications of this research, which are NOT accurately reported as a rule, are for "water drinkers" or for "indoor pool users". The information we provide here at the PoolForum has NOTHING to do with water you drink (or at least, it shouldn't!), and we rarely deal with indoor pools. For what it's worth, when I do make indoor pool recommendations, I do try to recommend things that will reduce DBP formation in indoor pools -- see this unfinished thread.