Added Clorox to Green Pool

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
chem geek
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Added Clorox to Green Pool

Postby chem geek » Thu 27 Oct, 2011 01:17

First off, there is no need to swear. Second, 6% bleach is identical to chlorinating liquid sold at pool stores (and hardware stores) except for its concentration. Personally, I use 12.5% chlorinating liquid from my pool store because it's reasonably priced and less weight to carry, but there is nothing wrong with using 6% unscented regular bleach if that is less expensive (per FC). There are tens of thousands of pool owners on multiple pool forums including this one, The PoolForum , and Trouble Free Pool who use 6% regular unscented bleach (usually an off-brand Ultra bleach since Clorox is not usually the least expensive).

There are many grocery store products that are IDENTICAL to pool store products as you can read in this post . As you can see from that post, Clorox Regular 6% bleach is registered with the EPA for use in pools and has instructions for doing so. "Liquid chlorine", as you call it, is not ten times as fast or a lot stronger than Clorox will ever be. 12.5% is roughly twice as concentrated as 6%, but that just means you need to use twice as much Clorox by volume. By using The Pool Calculator you can calculate the dosage needed to achieve the desired FC for a shock level -- that level being determined by the CYA level because the active chlorine that kills algae is roughly proportional to the FC/CYA ratio (read The Pool School for more info or if you are technically inclined you can read Certified Pool Operator Training -- what is not taught ).

Also, your comments about the high CH, though quite valid, are for a post from 2007. A CH of 400 ppm is also manageable without dilution to lower it. The TA can be kept lower and the pH was not too high so the saturation index was not too high either (the saturation index can be calculated in The Pool Calculator linked to above). Also, in that original post, the CYA was high so that requires a partial drain/refill to lower it so the CH would get lowered in that case anyway (unless fill water CH was high).


chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Added Clorox to Green Pool

Postby chem geek » Thu 27 Oct, 2011 21:13

P.S.

One example of a pool "let go" over the winter and getting cleaned up upon spring opening using bleach is shown in this thread (or this thread if you are unable to access the first link). Of course, if a pool is consistently maintained with chlorine (yes, even using bleach) at the proper FC/CYA ratio, then algae will not grow.
AllClearpools

Added Clorox to Green Pool

Postby AllClearpools » Mon 28 Nov, 2011 16:45

You can make your CL 1,000,000 and you will still have algae blooming in the water. Proof of such is that your CL is 7 and still have a problem. Your Alkalinty can actually be raised some to 140-170 and that helps sometimes. The main problem you have is the phosphate level in your pool water. Have this level checked and maintain as close to zero as possible. You will not ever have algae again. Period.
chem geek
Pool Industry Leader
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Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Added Clorox to Green Pool

Postby chem geek » Mon 28 Nov, 2011 20:18

AllClearpools wrote:You can make your CL 1,000,000 and you will still have algae blooming in the water. Proof of such is that your CL is 7 and still have a problem. Your Alkalinty can actually be raised some to 140-170 and that helps sometimes. The main problem you have is the phosphate level in your pool water. Have this level checked and maintain as close to zero as possible. You will not ever have algae again. Period.

That is not true.

In this post Ken reported a green pool full of algae (that post and this original thread is very old -- 2007). Then in this post he reports the shocking with chlorine was working. In this post, Ken says they got their algae-filled pool "nice and blue, clear as can be!" by shocking with chlorine, but then what they thought was some residual algae would not brush off. In that post he refers to 7 ppm FC, but the CYA is at least 100 ppm (many pool stores report 100 when it is far higher). That does not prove that chlorine doesn't kill algae as you imply with your "CL 1,000,000 and you will still have algae blooming in the water" since the water in fact did clear up by shocking with chlorine. As for what the residual actually ended up being, Ken never posted back so we'll never know. Green algae does not usually stay stuck to pool surfaces. It could be metal staining from the elevated pH from shocking with hypochlorite if Ken had used copper algaecide products in the past.

I had 3000+ ppb phosphates in my pool and yet was able to keep it algae free by properly maintaining the Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level. There are other pool owners on other forums who had even higher phosphate levels (even 5000 ppb) and were also able to prevent algae from growing. And there are tens of thousands of pool owners over multiple forums who keep their pools disinfected and algae-free using chlorine alone using a proper FC/CYA ratio regardless of phosphate or nitrate levels. Not only some on this forum, but over 27,000 users at Trouble Free Pool and over 11,000 at The PoolForum .

High nutrient (phosphate and nitrate) levels can only increase algae growth up to a point. Algae growth is ultimately limited by sunlight and temperature and roughly doubles in population every 3 to 8 hours in ideal conditions. If the active chlorine level (roughly proportional to the FC/CYA ratio) is high enough, then it kills algae faster than it can reproduce. In manually dosed pools, that required FC level is roughly 7.5% of the CYA level. For saltwater chlorine generator pools it is roughly an FC that is 5% of the CYA level.

Think of wood for a fire being nutrients and the fire being algae growth. It doesn't matter how much wood (fuel) you have so long as you keep dousing the match you try to use to start a fire, the water for dousing representing chlorine.

Now it is true that if you remove algae nutrients, such as phosphate, then algae cannot grow, but phosphate removers only remove inorganic phosphate (orthophosphate) and do not remove organic phosphates. Nevertheless, algae do not take in organic phosphates as quickly so their growth is limited when you use a phosphate remover, but if you let the chlorine level get to zero, then bacteria can grow and convert the organic phosphates to orthophosphate and algae can grow quickly again. So a phosphate remover needs to be seen in the same vein as an algaecide -- something that can help control algae growth as insurance in case you get lax with chlorine levels, but that it is not necessary if one maintains the proper minimum FC/CYA ratio.

As for raising the Total Alkalinity (TA) to the high levels you suggest, you would only do that if you were using a very acidic source of chlorine such as Trichlor. If you were using a hypochlorite source of chlorine (chlorinating liquid, bleach, Cal-Hypo, lithium hypochorite), you want the TA to be lower to prevent the pH from rising too quickly over time. TA is a measure mostly of bicarbonate in the water and pools are intentionally over-carbonated to provide pH buffering and to protect plaster surfaces. However, that over-carbonation leads to carbon dioxide outgassing which causes the pH to rise. Therefore, as ironic as it may seem, when using a hypochlorite source of chlorine, having a lower TA level leads to greater pH stability.

Since you suggested raising the TA to such a high level, I suspect that your pools use Trichlor. Were you aware of how quickly Trichlor increases the Cyanuric Acid (CYA) level if there is no water dilution? The following are chemical facts independent of concentration of product or of pool size:

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 2 ppm FC per day chlorine usage, this is an increase in CYA of 36 ppm per month. There is no wonder why so many Trichlor pools end up getting algae towards the end of the swim season if the FC level is not raised in proportion to the CYA level (or unless an algaecide or phosphate remover is used or weekly shocking is done in the hopes of making up for the "too low" FC/CYA ratio).

There are many fallacies and myths in the pool and spa industry. Even the rather good CPO course has some errors or omissions and you can read more about that including peer-reviewed scientific sources in Certified Pool Operator (CPO) training -- What is not taught .
Guest

Added Clorox to Green Pool

Postby Guest » Mon 02 Sep, 2013 21:44

Very helpful. "Fucking" appreciate it.

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