Where do you buy your chlorine?

[lifey8]

I currently have a pool service cleaning my pool but I am thinking about taking it over. I noticed that our pool guy puts a chlorine tablet in a slot near our pump and dumps in liquid chlorine once a week. Does anyone buy their chlorine (tabs or liquid) through the internet or a catalogue? Where are the best prices? I have heard people use chlorax from the grocery store - is that an acceptable method to "shock" the pool weekly? Thanks!

[floridapooltech]

I currently have a pool service cleaning my pool but I am thinking about taking it over. I noticed that our pool guy puts a chlorine tablet in a slot near our pump and dumps in liquid chlorine once a week. Does anyone buy their chlorine (tabs or liquid) through the internet or a catalogue? Where are the best prices? I have heard people use chlorax from the grocery store - is that an acceptable method to "shock" the pool weekly? Thanks!

While you can use grocery store bleach to sanitize your pool, it is only 6% active chlorine (sodium hypochlorite), while the chlorine you will buy at a pool store can be anywhere from 12-15% active. Depending on how many gallons your pool is will tell you how much of which you will be putting in your pool. The tablets he is most likely placing in an automatic chlorinator which will be on the return line after all your equipment. You can place one to three of these in at a time. Any more questions, feel free to post them on here!

[chem geek]

lifey8,

The tablets are likely to be Trichlor and you get those either at a pool store or some big-box stores (Home Depot, etc.) and may be called "stabilized chlorine tablets". Just realize that continued use of Trichlor (or Dichlor) will increase the Cyanuric Acid (CYA) level of the pool making the chlorine less effective against preventing algae growth. Read the Pool School for more info.

[lifey8]

Am I better off using another product besides the chlorine tablets in my pool?

[floridapooltech]

Am I better off using another product besides the chlorine tablets in my pool?

No. CYA (cyanuric acid) is actually good at certain levels. Levels of CYA too low will allow the sun to burn off your chlorine extremely quick, however, CYA levels too high will require a much higher FC level in order to achieve effective sanitation. You want to make sure your CYA is at 30-50 ppm with FC of 3 ppm. It would be ok if you were to use the tabs, and switch to just liquid chlorine every now and then keeping an eye on your CYA. Just remember, once CYA is way too high, you will have to dump water and replace with fresh to bring it back down!

[Allen G Myerson]

You should use regular, unscented 6 % bleach or liquid chlorine as your primary source of chlorine. I advise against lithium or calcium hypochlorite.

What is your cyanuric acid level?

[floridapooltech]

You should use regular, unscented 6 % bleach or liquid chlorine as your primary source of chlorine. I advise against lithium or calcium hypochlorite.

What is your cyanuric acid level?

There is actually nothing wrong with using Cal-Hypo as it does not contain Cyanuric acid like dy-chlor and tri-chlor and actually contains a much higher chlorine content than liquid bleach or chlorine.

[chem geek]

There is no one "right" answer here. If one has a vinyl pool with low Calcium Hardness (CH) in the fill water, then using Cal-Hypo is OK so long as one pre-dilutes it and is careful to brush the pool in the area over a return flow where it is added (since any that settles to the bottom for too long could harm the liner). The CH will build up over time unless there is water dilution. However, if one has a plaster pool where the water is already saturated with calcium carbonate to protect the plaster or if the fill water is high in CH such that evaporation and refill will continually raise the CH, then it is best to avoid using Cal-Hypo as it would just make the CH rise more quickly which eventually can lead to scaling.

As for Trichlor tabs, one needs to monitor the Cyanuric Acid (CYA) level and either raise the FC target as the CYA level rises or dilute the water to keep the CYA in check or use (at extra cost) algaecides or phosphate removers to try and prevent algae growth. The following are chemical facts -- indisputable, yet not normally disclosed in this way by the pool/spa industry:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So even with a very low 1 ppm FC per day chlorine usage, Trichlor will increase CYA by over 100 ppm in 6 months if there is no water dilution. Normal chlorine usage is usually higher than this so the buildup of CYA is often faster unless one has rain overflow and/or significant backwashing. In my own pool 7 years ago, Trichlor pucks in a floating feeder raised my CYA from 30 ppm to 150 ppm in 1-1/2 years -- one 7 month swim season plus 4 months of a second season and I had a very low 0.7 ppm FC per day chlorine usage with my opaque safety cover, a cover pump that removed rain water (so no dilution) and an oversized cartridge filter cleaned only once a year (so minimal water dilution). 30 + (7+4)*30*0.7*0.61 = 171 ppm so no great surprise here given some water dilution and some chlorine oxidation of CYA over time. It's at that point that my pool water began to look dull and then cloudy as a nascent algae bloom was forming and the chlorine demand started to rise where I couldn't even keep up using Trichlor pucks alone. This was in spite of a 3 ppm FC target and using PolyQuat 60 algaecide, though I was only using it every other week (if I had used it every week, I could have possibly gone until the CYA was 200 ppm or somewhat higher). That's when I decided to learn pool water chemistry and take matters into my own hands as the pool store was of no help.

If you don't mind adding chlorine every day or two, then you can set your CYA level to something reasonable, probably around 50 ppm depending on where you live, and then use 10% or 12.5% chlorinating liquid or 6% unscented bleach. You can learn more by reading the Pool School. I use 12.5% chlorinating liquid in my 16,000 gallon pool (shown here and here) that I add twice a week (because the chlorine usage is only around 1 ppm FC per day due to the mostly opaque pool cover -- the pool is used more around 1-2 hours every day and longer on weekends) plus a small amount of acid every month or two. This costs me $15 in chemicals. That's it -- no algaecides, no phosphate removers, no clarifiers, no flocculants, no weekly shocking. And the same basic maintenance approach is true for tens of thousands of pool owners at both The PoolForum, Trouble Free Pool, and this forum. The key is knowing your water by using a good test kit and then only adding what is truly needed (and understanding the chlorine/CYA relationship).