Chlorine Tabs And Baking Soda Only?

[Nikki]

We have decided against the SWG this year (people around here just don't know enough about them and I don't feel educated enough about them).

My sister and brother in law have had their pool for 5 years now. 24 ft above ground (same size we're getting). He said the ONLY things he has ever put in his pool is chlorine tablets and baking soda (he buys it in 50lb bags at a local food supply store). He said he shocks it once a year (when they open it after the winter). Their pool has always been super clear. He said that he uses the Aqua check test strips to test it.

Has anyone else ever heard of only having to use these 2 things and had success?

I am trying to cut back on as many unnecessary chemicals as possible (I have sensitive skin).

[chem geek]

If he is using chlorine tablets then depending on the type of tablets two problems can occur. If the tablets are Trichlor, then a buildup of Cyanuric Acid (CYA) is possible depending on how much splash-out or backwashing is done (since that dilutes the water and everything in it). Too much CYA and the chlorine becomes less effective. If you don't raise the Free Chlorine (FC) level when the CYA gets high, then you can get algae (unless you use an algaecide).

If instead he is using Cal-Hypo tablets, then this increases Calcium Hardness (CH) over time, but that is less of an issue though eventually will need dilution as well.

Since he is adding Baking Soda regularly, I suspect he is using Trichlor since that is very acidic. Adding Baking Soda raises the Total Alklainity (TA) which when high will cause the pH to rise, especially with aeration of the pool water.

The least amount of chemicals would be to use chlorinating liquid or bleach (sodium hypochlorite) since the pH will be most stable in that situation if the Total Alkalinity (TA) level is kept low (80 or below). The CYA level should be kept around 30-50 ppm. This is all I use in my pool and only on rare occasions do I add a little acid to maintain pH. However, the downside is that you need to add it probably every day if the pool is exposed to sunlight. If you have a pool cover (as I do) then you may be able to add it only twice a week.

[Nikki]

I think he said the chlorine tablets were AquaClear brand....or something along the lines of that (I am not familiar with all the brands). He said they are the 3 inch tablets and he buys them at ACE hardware. BTW, he has a sand filter (same that we will have). Not sure if that matters.

When you say bleach, do you mean the same kind of bleach as Clorox? I tried reading about the Bleach, Boric Acid and Baking Soda (BBB) method, but there is a lot of pool lingo that I don't understand (for instance, I don't understand really what CYA is and why it's so important).

I'm scared to death that this pool is going to be a pain like our old 12ft above ground. I know it had a tiny filter and all, but it was a nightmare trying to keep clean (no vacuum....just the little thing that you hook up to the water hose) and keep the chemicals balanced!

[Trigger]

Has anyone else ever heard of only having to use these 2 things and had success?

Yup.

Me.

With the exception of adding some shock after the 4th of july party, (50 folks with butter covered kids. Yuk.) chlorine and ph plus are the only chemicals I add to the pool and I have great luck. (21' ft above ground ) What other chemicals are you adding to the pool?

I shock when I open, and keep the chlorine levels up and I'm pretty good all year. I filter every day (sand filter) for about 2-3 hours. I use just the 2 bottle reagent kit (Chlroine and PH) to measure the water and in the past 8 years things have been great. I had 1 bout with algei a few years ago after a long spell of rain and I slacked on the filtering and chems. OTher than that, I have great water. ( I also close and winterize the pool properly)

Bleach: Yes. They are telling you to use Clorox. (or rather laundry bleach).

I don't. As Geek said, you are constantly measuring the acid to keep it effective. I'm not sure if any agencies agree or accept what amout of levels you should have to keep the water safe? Is bleach an approved sanitizer?

Bleach, you can use it, but trichlor (pool chlorine) isn't that exspensive and it's pretty easy and understood by the industry. The Bleach folsk strike me as folks out to prove something (which is fine, i guess) however Laundry bleach is pretty weak, I'd think you'd be adding quite a bit (and make sure you don't use any bleach with additives and such) and it breaks down quickly in the sunlight.

But for you and me, who just want to use the pool and not have issues use a quality tirichor puck in a feeder, (I drop mine in the filter basket. ensure you have good filtration, backwash often, vacum once a week, and watch the PH and you should be fine. Don't micro manage your water. But keep a steady eye on it.

It is that easy.

[chem geek]

Chlorinating liquid (pool chlorine) from the pool store is the same as unscented bleach (Clorox regular) except in strength. The bleach is about half the strength of the chlorinating liquid. And yes, Clorox Regular is an approved sanitizer with the EPA for use in pools which is why it not only says 6% concentration of sodium hypochlorite by weight on the bottle, but also says "5.7% Available Chlorine". That's required by the EPA when used as a sanitizer. As I said, using bleach or chlorinating liquid is less convenient unless you have a pool cover that prevents UV from the sun getting to the water. Trichlor tablets are more convenient.

Just for clarification, when using chlorinating liquid or bleach you aren't "constantly measuring the acid to keep it effective". I only had to add acid twice last year and only a very small amount. The concept that chlorinating liquid or bleach makes the pH rise is simply not true because though the initial addition causes a rise (since hypochlorite has a high pH), the usage of chlorine (breakdown from sunlight, oxidation of organics and ammonia, etc.) is acidic so the net effect is neutral pH. If a lower TA is maintained (not more than 80), then there is less of a rise in pH for technical reasons I won't get into here (has to do with the pool being "over-carbonated"). Pretty much the only chemical people add to their chlorinating liquid or bleach pools is the chlorine -- addition of much acid is very rare unless the pools have a lot of aeration features (waterfalls, fountains, spillovers, negative edge, etc.). Pools that use a saltwater chlorine generator (SWG) also typically experience a rise in pH and this is actually due to aeration from the hydrogen gas bubbles produced in the SWG (you can see them at night with a pool light if the pump and SWG are turned on).

Cyanuric Acid (CYA) is needed to protect chlorine from getting destroyed by sunlight. If you had no CYA in the water, then about half of the chlorine would break down from the sun around noontime in the summer in about a half-hour. With CYA, it will take more than a day for half of the chlorine to break down from the sun. The Trichlor pucks/tabs contain both chlorine and CYA (for every 1 ppm FC added by the Trichlor you also get 0.6 ppm CYA). The problem is that while chlorine gets used up so you need to add more regularly, the CYA does not get used up and instead accumulates. If you regularly backwash a filter and have a smaller pool, then the dilution of water can keep the CYA levels in check, but otherwise they can build up. Around 30-50 ppm CYA works to protect the chlorine reasonably well without reducing chlorine's effectiveness too much. Higher CYA levels require higher chlorine levels to have the same amount of disinfecting chlorine in the pool. The CYA essentially combines with most of the chlorine in the water and though that protects it from sunlight, it also prevents it from disinfecting so there's a balance.

You can absolutely use higher Total Alkalinity (TA) with Trichlor and just add Alkalinity Up (or baking soda) to maintain the pH (or can use pH Up instead as Trigger does -- I think that's more efficient). However, if you use Trichlor and the CYA levels build up, then you either have to maintain higher Free Chlorine levels or need to use a weekly maintenance dose of algaecide (PolyQuat 60) or else you risk getting algae. It's a risk, not a certainty, of getting algae when the CYA is high (say, 80 ppm or higher) with too low Free Chlorine (say, 3 ppm or lower). Every pool that has had an algae problem on this and other pool forums was due to either having no chlorine (usually over the winter) or from chlorine levels that were too low relative to the CYA level. Not one pool that has maintained Free Chlorine levels relative to their CYA level has had algae -- not one single report. This chart shows the required chlorine level at various CYA levels. The 0.05 column in this chart is a similar "goal" to use (the 0.03 column is a minimum, but you should also have a minimum of 2 ppm FC in the pool regardless of lower numbers in this latter chart at low CYA levels -- you need some chlorine in "reserve" not just at levels that will kill pathogens quickly enough). If you live in an area that gets mustard/yellow algae, then slightly higher chlorine levels may need to be maintained (the 0.07 column in the chart).

There is no one right answer for every pool since every pool is different in size, whether a cover is used, in the amount of aeration features (waterfalls, etc.). The choice is up to you, but if you use Trichlor either watch the CYA levels and drain/refill or regularly backwash to keep the levels low or maintain Free Chlorine levels accordingly (or use a weekly algaecide). In my pool, I have a cartridge filter (so there is no backwashing) and an opaque pool cover and when I first got my pool my CYA levels got over 100 ppm in less than a year and a half. If I didn't have the pool cover, I would have reached over 100 ppm in less than a year. When the CYA was high, I was having a very hard time maintaining chlorine levels and the water would be cloudier -- I was fighting algae and didn't even realize it at the time. The Trichlor tabs in the floating feeder also rusted the stainless steel mountings closest to where the floating feeder parked itself, so if you use a floating feeder make sure it stays away from any metal and probably away from the sides as well (Trichlor is highly acidic so when the pump is turned off the water around the floating feeder becomes highly acidic as well). If you drop the Trichlor in the filter basket, be sure to keep the pump running at all times. The Trichlor is highly acidic and if the pump is not running then the water in the area of the filter basket will become highly acidic -- if that's near a pump, the pump may get damaged -- if it's a skimmer basket, then the plaster in the area outside the skimmer may corrode (I had a thermometer rust that was just outside the skimmer when I used Trichlor in the skimmer basket and didn't keep the pump running at all times).

I used Trichlor tabs in a feeder at the start of this season since I wanted to get my CYA levels back up (they had dropped some over the winter), but have now switched back to using 12.5% chlorinating liquid from the pool store. If you use either chlorinating liquid or bleach, you don't keep those bottles in the sun because as was pointed out the chlorine will breakdown even with heat. I have not found any problem using the chlorinating liquid even though it only lasts around 6 months -- I typically use it within a month and my pool store has good turnaround. Bleach lasts FAR longer due to its lower concentration. The chart at the bottom of this page shows how long it takes for half of the chlorine to decompse at different temperatures and concentrations. Bleach (which is typically 6.2% "Trade" in strength) loses half of its strength in about a year. As for pricing, Trichlor is the least expensive source of chlorine in some parts of the country as seen in this chart (near the bottom of the post) or this chart which uses different sources.

[Trigger]

I don't even measure my CYA.

[chem geek]

But you said you backwash regularly so you may be diluting it at the same rate you are adding it. It would be interesting to measure it and see what level it is and what Free Chlorine level you maintain. Remember I said that smaller pools that backwash regularly will dilute everything in their pool. If that's your situation, then not only would you be keeping your CYA in check, but you would be diluting the Calcium Hardness (CH) as well. Have you checked that or do you have a vinyl pool so it doesn't matter? I see you have an above ground pool, so that's vinyl so CH doesn't matter and your fill water has some. So your situation may be different than someone with a plaster/gunite pool since regular backwashing will cause dilution that will require addition of calcium chloride.

Also, do you use Dichlor exclusively in a hot tub? That also has the same CYA vs. chlorine issues such that some states do not allow Dichlor to be used in commercial hot tubs (see this link). I think that's too extreme since some CYA in hot tubs is a good thing -- not for protection from sunlight but to keep disinfecting chlorine levels from being TOO high. I also assume you saw this post of mine a while back where I consolidated the references on this forum to hot tub itch -- all of these users used Dichlor exclusively and developed itching problems after about 1.5-2 months or in one case was diagnosed by a doctor as having hot tub lung (caused by inhaling the bacteria that causes hot tub itch).

[chem geek]

Nikki,

So if your pool is small (< 10,000 gallons) and you backwash your sand filter regularly, then the Trichlor should work for you just as it does for Trigger. The regular backwashing should keep the CYA at a reasonable level. I would still suggest testing it at least to see where it settles into -- you don't have to test it very often. Even once a month or two is plenty since it takes a while to build up. Just maintain a higher chlorine level if the CYA rises or if you want to maintain lower chlorine levels then you can use an algaecide (PolyQuat 60) to keep away algae. Just keep in mind the cautions I had about Trichlor's acidity -- keeping a feeder away from metal and/or keeping the pump running. Some people get an inline feeder which won't require such precautions since the feeder only injects into the water flow when the pump is running.

[Trigger]

Oh, I'm not argueing or disagreeing with you Geek and I belive I've followed what you said (and am not sold on the bleach for me). But Nikki was wondering if she could use chlorine and backing soda (ph up) to keep her 24' above pool clean?

Yup. I think you gave me a quick primer on bleach in the hot tub thread. I sanitize with Dichlor and shock with MPS. I still get some itch. Is this from the CYA levels in the tub? Can I check and adjust the CYA in a hot tub without going the bleach route?

[chem geek]

I think we both answered Nikki's question with a "yes" that she can use Trichlor tabs/pucks plus baking soda (though I think pH Up / Washing Soda is better and is what you use -- by the way, Arm & Hammer Super Washing Soda in the yellow box is identical to "pH Up" products -- both are Sodium Carbonate) and her situation sounds more similar to yours so things should work out. At least she knows the pros/cons and can make an informed decision.

As for your itch, it may not be from Pseudomonas aeruginosa which is the bacteria that causes hot tub itch, but if it is then it's likely to be there because of using Dichlor exclusively, especially if the itch gets worse or appears after the first month of use after a fresh fill. The solution is to use Dichlor for a week or two after a fresh fill and then to switch to a source of chlorine that does not contain CYA. Unfortunately, there aren't that many choices. You can use chlorinating liquid or bleach, but for a hot tub bleach makes more sense since you don't need the higher concentration and bleach is usually cheaper (Clorox Regular). You could use the very expensive Lithium Hypochlorite which is a very fast-dissolving powder. Or you could use Cal-Hypo (calcium hypochlorite) but since that is slower to dissolve it should be mixed in a container of water (you can use spa water if you want) outside the hot tub before being added. The problem with Cal-Hypo is that for every 1 ppm Free Chlorine (FC) you add, you will also get 0.7 ppm Calcium Hardness (CH) so that will build up. If you add 4 ppm FC per day, then that's adding 84 ppm CH per month. If your fill water is low in CH, then this would be OK since you would likely change the water after 3 months anyway. So there are options, but for a hot tub I think bleach truly is the easiest (you add it every day).

By the way, Dichlor has less chlorine for the same amount of CYA or put another way, for every 1 ppm FC added by Dichlor, you add 0.9 ppm CYA (remember that Trichlor added 0.6 ppm CYA). If you add 4 ppm FC per day, then every month you would increase CYA by about 100 ppm and unlike your pool, there is no backwashing. You build up CYA until your next drain/refill (usually after 3 months).

If you add Dichlor so that you accumulate around 20 ppm CYA (so that's adding about 22 ppm FC cumulatively or about a week at 4 ppm per day) and try to maintain 4 ppm FC, then that will keep away the hot tub itch bacteria. This is conservative so you may add chlorine to get to 6 ppm FC and then the next day it may be 2 ppm FC when you add it again and that's fine. The net result will be a disinfecting chlorine level that is technically equivalent to 0.2 ppm FC with no CYA and is about 4 times higher than what is recommended to be maintained in pools because the hot tub itch bacteria is harder to kill than even pool alage.

Even with the modified "Dichlor then non-CYA chlorine" route, you would still use MPS on a weekly basis, mostly to prevent combined chlorines from forming since the hot tub isn't generally exposed to sunlight (which tends to help break down such combined chlorines) and because the water volume is so small that there are a lot of organics to break down so it's better for MPS to do that than chlorine.

One more thing -- normally the bacteria that causes hot tub itch is introduced into a hot tub from bathing suits. I'm guessing that your soaking in the tub with the chlorine at sufficiently high levels should kill it, but you should consider washing the suit thoroughly with soap as well (though I'm not sure if that will kill this particular bacteria -- soap usually does a decent job getting rid of most bacteria).

[Trigger]

I get the itch while further into the water usage. No one else who uses the tub gets it, but I am the one who uses the tub the most. I thought it was just the winter air and dry skin, but perhaps it's high CYA? I checked and saw that I can buy some CYA test strips for under $10. So I think I'll start to monitor the CYA and see if I notice a corelation.

[chem geek]

Not everyone is susceptible to the bacteria that causes hot tub itch. It partly depends on whether you have any wounds on the skin, but also depends on the individual's ability to fight this particular bacteria. In some sense, it's like an allergy in that some people are more susceptible than others.

Just so you know, the test strips are notoriously inaccurate, especially for CYA. Since you don't drain/refill your tub, you can just keep track (a log) of how much chlorine you add and if it's Dichlor then just multiply the amount of FC you raised by 0.9 to get the amount of CYA you added. Of course, the strip should give you at least a rough idea of the increase over time. The Taylor K-2006 test kit has everything for both pool and spa (for chlorine) as shown in this link and you can get it less expensively at other stores including Leslie's Chlorine FAS-DPD Service Test Kit here. These tests will measure from 30-100 ppm CYA (you can dilute the test sample with tap water to measure higher amounts). The Taylor K-1721 test kit will test for CYA alone from 30-100 ppm here while the Taylor K-1720 test kit will test for CYA alone from 20-100 ppm here.

And please post at what CYA level and regular FC level you first start to notice the itch (in a month or so when it probably occurs). That would be useful information since all I've been going on is what are known as "CT" values of 30-50 for 99.99% (4-log) kill of this bacteria, but that data was at lower temperatures. Usually the CT value declines at higher temperatures so less chlorine would be needed. My "20 ppm CYA with 4 ppm FC" takes this into account based on the equivalent 50% kill CT value over 15 minutes, but it's really just an estimate, but if it's conservative then it at least solves the problem.