no chlorine

[chem geek]

John (Nagrath),

Make sure you are using a chlorine test that does not get bleached out -- a FAS-DPD test is best, but even an OTO test would tell you that the problem isn't the chlorine test. If the test is accurate, then get an inexpensive ammonia test kit from a fish/pet/aquarium store and see if you have ammonia in the pool. If you do, then it will take at least 8x the ammonia amount in chlorine to get rid of -- possibly more (due to intermediate products). You can do a bucket test to see how much chlorine it will take (by scaling appropriately).

It would be strange to have ammonia in the pool if you indeed had no CYA in the pool at all. Note that if you ever used stabilized chlorine (Trichlor pucks/tabs or granules, Dichlor powder) then your pool does have CYA in it. You refer to running the chlorinator full open and usually a "chlorinator" is a Trichlor puck feeder, probably inline. For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm so you could have had a LOT of CYA in the water so could, in fact, had bacteria convert it to ammonia when the FC dropped to zero.

Alan,

Please do not use all caps. It is very hard to read.

As for salt pools, there are plenty of salt pools that get algae -- it is not a panacea for preventing algae growth. Even salt pools with a saltwater chlorine generator (SWG) can get algae if they follow the industry recommended FC of 1-3 ppm with a CYA of 60-80 ppm because at 80 ppm CYA you need a minimum of at least 3.6 ppm for the chlorine to kill algae faster than it can grow and given overnight loss a minimum FC of 4 ppm is better in SWG pools with that CYA level. If you want to add something to your pool in a one-time dose with minimal side effects to inhibit algae growth, then 50 ppm Borates would be a better choice. Copper ions (that you mentioned with a copper-based algaecide) are also a one-time dose and definitely can prevent algae, but the metal ions can also stain.

Salt in the pool doesn't affect what chlorine does. The higher salt levels let your eyes not feel as much pressure because the salinity in the pool is higher and closer to the 9000 ppm of your tears. That's all. If your eyes are opened in water with a low salinity, then water tends to enter into the eye creating pressure. There is no mystery here. However, higher salt levels are also more corrosive so there is no free lunch. You can read about some of the problems in this blog though most people are happy with their SWG pools. If you've got soft hardscape stone or less expensive stainless steel or have aluminum such as in pool covers or have metal diving board bases, etc., then you need to be more careful about the faster corrosion.

Salt does not "ionize the water". It does increase what is called the "ionic strength" and that slightly shifts chemical reactions towards the side that has more charged ions because such ions are somewhat shielded, but that's all and it's not a big deal. It doesn't speed up chemical reactions or make things more powerful. It also does not change the speed at which chlorine breaks down from sunlight or other sources, though obviously Cyanuric Acid does that effect in a huge way.

I do NOT recommend the LaMotte test nor test strips. I recommend the Taylor K-2006 kit which can be obtained at a good online price here or the TF100 from tftestkits.net here. These both have the FAS-DPD chlorine test that can measure both Free Chlorine (FC) and Combined Chlorine (CC) accurately to with 0.2 ppm using a 25 ml sample or 0.5 ppm using a 10 ml sample. Unlike DPD chlorine tests, they do not bleach out and can measure up to 50 ppm. They are far more accurate then DPD or OTO tests and test strips (and if LaMotte had a FAS-DPD chlorine test in their kit, then I'd probably recommend that as well). As for test strips, they do not test for Calcium Hardness (CH) -- they only test Total Hardness which is not relevant for calculating the saturation index used to protect plaster surfaces.

Cyanuric Acid (CYA) does not just protect chlorine from sunlight. Though it does absorb UV from the sun shielding lower depths of water, it mostly combines with chlorine to produce chemical (called chlorinated isocyanurates) that are not effective sanitizers nor oxidizers. CYA significantly lowers chlorine's strength and this is very important to know since the FC/CYA ratio is what roughly determines the amount of active chlorine in the water and the amount of chlorine you need to prevent algae growth. See this post for more info on this.

As for phosphates, you are correct that it is not necessary to remove them in order to prevent algae growth. A sufficient FC level relative to the CYA level will prevent algae from growing. Phosphate removes should be seen in the same vein as algaecides -- something that, at extra cost, can lower the rate of algae growth, but not necessary if sufficient chlorine is used. It's more like insurance. You also bring up the interesting true fact that alum flocs also tend to lower phosphate levels (especially very high phosphate levels) though the lanthanum based products are typically used to lower phosphate levels that have already been lowered to at least 1000 ppb by other means.

Though clearing a pool of ammonia can certainly be done with many different oxidizers, including non-chlorine shock (potassium monopersulfate, MPS), it can also be done much less expensively with chlorine alone. As for CYA getting converted into ammonia by bacteria (when the FC gets to zero allowing the bacteria to grow) I describe that here.

Richard

[Pool User]

mY gOD!!!!...jUST CALL ME i HAVE A PERMANANT SOLUTION AND NO CHEMICALS...NO FEARS...AND NO PATHOGENS......NO ALGAE..NO NOTHING..JUST CLEAN, HEALTHY WATER 24/7 I AM A WATER TREATMENT PROFFESSIONAL...SO I HAVE NO "DOG" IN THIS HUNT! IN OTHER WORDS I AM NOT SELLING POOLS OR CHEMICALS!!!

[lbridges]

... A PERMANANT SOLUTION AND NO CHEMICALS....

I'm sorry, but I think I have to raise the BS flag for this claim. But I will gladly eat some crow if I'm wrong.

[swimnsaveusa]

It would be wise not to shock the pool as often as your claiming as this will in fact damage the pool's surface. It is possible that you may have over chlorinated your pool to the point a test kit will not register correctly. Another alternative, if however this is not the case, is to add a stabilizer (cyanuric acid) which will slow the rate chlorine will evaporate and lose it's effectiveness. If you have any further questions, feel free to contact our service dept. on the web as we have a "do it yourself" guide filled with tips, advice and tools. We also run promotions for free products, sales, offers & giveaway's.

[nagrath]

Richard,
It seems that I am still struggling with this problem; I opened up the pool this spring; it was slightly greenish and slightly cloudy; used a Trichlor shock product twice, and the pool cleared up pretty quickly (3-4 days); however, once again I am getting no free chlorine. Pool store tested (using a photometric reader, though I don't know the test they use (it IS a drop test, though), and I came up with ph 7.2, total alk 100, cya 0, free chlorine 0, phosphates 0. How is it I am getting a CYA of zero if I shocked with trichlor and have been using 3" trichlor tabs in my chlorinator? Can the chlorine bleach out the CYA test? I will get the ammonia test; I should have done that last year but did not. Do I correctly understand that I can use regular liquid bleach (if it is unscented) to shock (especially in this case, if I need to add a tremendous amount)? I am nearly at my wits end; the pool looks beautiful, but I get no chlorine reading, even though I smell chlorine when I open the pool. Ugh!

Thank you for all your help; I wish I had followed through on everything last year.

Sincerely,
John

[delmonteken]

Hi Richard
I am over in Spain and I am interested in the fact that you are not getting a reading as it would appear that I am not either. What I would like to know is when you do the test for chlorine what colour does your water go when you put the drops in your test kit. The reason me asking is my water does not go the yellowish colour to get a reading , mine goes like and orangy colour this is what I can describe the colour as. And its driving me crazy. I have shocked my pool done a test and nothing still the same orangy colour. So if you can help in any way or anyone else who reads this I would greatly appreciate anyones help on the matter

Richard,
It seems that I am still struggling with this problem; I opened up the pool this spring; it was slightly greenish and slightly cloudy; used a Trichlor shock product twice, and the pool cleared up pretty quickly (3-4 days); however, once again I am getting no free chlorine. Pool store tested (using a photometric reader, though I don't know the test they use (it IS a drop test, though), and I came up with ph 7.2, total alk 100, cya 0, free chlorine 0, phosphates 0. How is it I am getting a CYA of zero if I shocked with trichlor and have been using 3" trichlor tabs in my chlorinator? Can the chlorine bleach out the CYA test? I will get the ammonia test; I should have done that last year but did not. Do I correctly understand that I can use regular liquid bleach (if it is unscented) to shock (especially in this case, if I need to add a tremendous amount)? I am nearly at my wits end; the pool looks beautiful, but I get no chlorine reading, even though I smell chlorine when I open the pool. Ugh!

Thank you for all your help; I wish I had followed through on everything last year.

Sincerely,
John

[chem geek]

John,

Just so I understand, you got through this problem last year and finally got the pool to read Free Chlorine (FC) OK, but now you've opened up the pool again this year and have a similar problem, correct? If you let the chlorine level get to zero over the winter, then bacteria could certainly have converted some or all of the CYA into ammonia or at least started to break it down. That can create a huge chlorine demand. You can prevent this by either maintaining some chlorine in the pool over the winter or at least closing when the water is cool (50ºF or below) with a shock level of chlorine and then open the pool in the spring before the water warms up (still 50ºF or below).

So you can get an ammonia test kit to see how much ammonia there is in the pool. You can also do a bucket test to determine the chlorine demand where 1/4 teaspoon of 6% bleach in 2 gallons of pool water is 10 ppm. Add the bleach, stir, test after 10-15 minutes, see if you get an FC reading. If the FC is low, add more chlorine and repeat until you get a consistent FC reading of at least 10 ppm. This will give you a rough idea of how much chlorine you need to add to the pool -- it could be a lot.

You can use chlorinating liquid from a pool store or hardware / big-box store if they carry it or you can use Clorox Regular 6% unscented (or off-brand Ultra unscented) bleach for the pool.

Richard

[chem geek]

Hi Richard
I am over in Spain and I am interested in the fact that you are not getting a reading as it would appear that I am not either. What I would like to know is when you do the test for chlorine what colour does your water go when you put the drops in your test kit. The reason me asking is my water does not go the yellowish colour to get a reading , mine goes like and orangy colour this is what I can describe the colour as. And its driving me crazy. I have shocked my pool done a test and nothing still the same orangy colour. So if you can help in any way or anyone else who reads this I would greatly appreciate anyones help on the matter

It sounds like you are using an OTO test kit. This will not bleach out at high chlorine levels and instead will go from yellow to orange to even red or brown when the chlorine level gets very high. So it sounds like you have a lot of chlorine in your pool -- probably in the 10-20 ppm FC range.

So your chlorine level is probably too high, but you have a lousy test kit. Since you are in Spain, see if you can get both a PalinTest SP 315C (Balanced Water and Chlorine/pH/Cyanuric Acid) and also SP 300 (FAS-DPD chlorine test). The 315C tests for FC, TC, pH, TA, CH, CYA while the 300 is a better chlorine test for FC and CC that won't bleach out and can accurately measure shock levels of chlorine. You really need a test that can check your CYA and other levels.

Is your pool vinyl lined or is it plaster or fiberglass? You mentioned in an E-mail that your pool walls are becoming discolored like a dary grayish going blackish in color in the grout lines -- is this a tile pool? I've never heard of high chlorine levels turning plaster walls gray.

[nagrath]

Richard,
Thanks! I have my work cut out for me and will do just what you say tomorrow. Pool was shocked and closed when cool, and opened when cool, but I JUST BARELy got the chlorine level up in the fall when I was last having the problem, and maybe I was fooling myself. I will get to work on this tomorrow; Thanks a million!

John

[nagrath]

Richard,
Got the test kit for ammonia--4 ppm. Had water retested at another pool store with very modern equipment. Total chlorine 2.7, free chlorine 0, CYA 30, alk 60 (that just dropped from ~100 at last test) Hardness 83, pH 6.6; they suggest 12-14 bags of shock/bottles of liquid shock. I have not done the bucket test yet. Their granular shock is Calcium hypochlorite; I bought some, as the price was good and it was convenient; is this OK to use to super-hyper-chlorinate and break the combined chlorine, as we discussed doing with liquid chlorine? Also, I was told to balance the pH and alkalinity and hardness before chlorinating. However, I am thinking the calcium ions in the calcium hypochlorite will add to the hardness, no? Should I use less of the hardness product? I could not get a good liquid test kit, but got LaMotte test strips which appear to be more accurate and do test hardness and total chlorine as well as free, and match the store's testing pretty well. Any words of wisdom and experience?