Need Chem geeks advice

[Vetsa]

Hi Richard
Just wanted to check that this bleach was type was okay. These are the listed ingredients (please forgive spelling errors as it's written really small and hard to read)

Sodium Hypochrite 42g/L
(available Chlorine 4%m/v) at used by date
available chlorine 2%m/v Sodium Hydroxide 9/L

My pump packed it in and have been getting the run around with the company trying to get a new one it's been 10 day since it been running. (I have SWC).

So far the water is still clear (I haven't let anyone swim in it, yuck) but was wondering what I should do. If all goes well will have the pump in 3 days.

appreciate any advice
Thanks
Vet

[chem geek]

Hi Richard
Just wanted to check that this bleach was type was okay. These are the listed ingredients (please forgive spelling errors as it's written really small and hard to read)

Sodium Hypochrite 42g/L
(available Chlorine 4%m/v) at used by date
available chlorine 2%m/v Sodium Hydroxide 9/L

My pump packed it in and have been getting the run around with the company trying to get a new one it's been 10 day since it been running. (I have SWC).

So far the water is still clear (I haven't let anyone swim in it, yuck) but was wondering what I should do. If all goes well will have the pump in 3 days.

appreciate any advice
Thanks
Vet

Vet,

This is 4.2% bleach. I'm confused by the two separate Available Chlorine numbers -- it should be around 4% so I don't know what the 2% means. The Sodium Hydroxide is lye and is at 9g/L = 0.9% which is very high. It means that your pH will tend to rise when you use this source of chlorine -- it will not only rise when you add it (which always happens with hypochlorite sources of chlorine), but even after the chlorine gets used up you'll end up with a net pH rise.

6% Clorox Regular bleach has negligible lye in it -- about 0.02% resulting in a net pH of 11.4 of the bleach in the bottle. Typical 12.5% chlorinating liquid has about 0.25% lye resulting in a pH of 12.5. The bleach you quoted probably has a pH close to 13.5. Are you sure it said 9 g/L for sodium hydroxide and didn't say 0.9 g/L?

If you use this bleach you quoted, then for every 4.3 ppm FC that you add and then after that chlorine gets used up, you will raise the pH by about 0.08 if your TA is 100 and your starting pH is 7.5. So over time you'll need to add acid. Technically, adding one liter of this bleach to 10,000 gallons has the same effect on pH as 11.6 grams of Soda Ash.

So if you use this stuff, just be aware that you'll be needing to check on the pH after the FC drops back down and will have to add acid. For every liter of this stuff that you use, you'll need to add 23 ml of Muriatic Acid (31.45% Hydrochloric Acid) or 29.5 grams of dry acid (93.2% Sodium Bisulfate) though generally the Muriatic Acid is preferred.

If you can find some bleach or chlorinating liquid that has less lye (sodium hydroxide) in it, that would be better. If you find a Material Safety Data Sheet (MSDS) on the product, then you'll want to find something with a pH no higher than 12.5 and preferably lower (the 11.4 of Clorox Bleach is great).

Richard

[Guest]

Hi Richard
Thanks for your reply. I checked the bottle again but couldn't see a point before the 9g/L but as I said before it is hard to read.

I don't think I'll use it, I'll just get something from the pool shop. I couldn't see Clorox on the shelf, here I did look for that first, the stuff I brought was White King, strength strong. In Australia so not sure if I can find that brand here.
Thanks again
Vet

[chem geek]

I just get 12.5% chlorinating liquid from my pool store. It's at a decent price and they also reuse the bottles -- I take my old ones back in the carton crate they came in and swap for 4 new bottles in a new crate. It's better than recycling!

[Vetsa]

Thanks again, another question, is the shock powder better or getting liquid like you suggested? I'm guessing the liquid seening though you use that but just want to check.
Thanks
Vet

[chem geek]

There is no such thing as a "shock" form of chlorine. Chlorine for regular use and for shocking is the same. There are only four powders available and they either add extra stuff you normally don't want or they are very expensive. In order of what's most common, especially as advertised for "shocking" they are:

Cal-Hypo: comes in granules that don't dissolve very quickly so you usually pre-dissolve it in a bucket of pool water first. For every 10 ppm Free Chlorine (FC) added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm. So if your CH is low, then using this form of chlorine can raise it over time. Otherwise, if you use this regularly and your CH rises, then you could get scaling. Cal-Hypo also comes in tablets used in special (NOT Trichlor) feeders, but they tend to break down too quickly and leave a residue.

Dichlor: comes in powder/granules and dissolves relatively quickly. For every 10 ppm FC added by Dichlor, it also increases Cyanuric Acid (CYA) by 9 ppm. Unless your CYA is low, you should not be using this product. The increasing CYA will make you have to either keep increasing FC proportionately or use a supplemental algaecide or phosphate remover to prevent algae.

Trichlor: though this normally comes in pucks/tabs, it also is available as powder/granules though like Cal-Hypo may need pre-dissolving in a bucket of pool water. For every 10 ppm FC added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. Unless your CYA is low, you should not be using this product. The increasing CYA will make you have to either keep increasing FC proportionately or use a supplemental algaecide or phosphate remover to prevent algae.

Lithium Hypochlorite: this is a somewhat fast dissolving powder and like bleach and chlorinating liquid it doesn't add anything extra to the water except salt. However, it is VERY expensive compared to other sources of chlorine.

Richard

[Vet]

Thanks Richard for all your help again .
Got the pump today and it's all systems go,Yay!

Cheers
Vet

[Nadine Ord]

Hi Pool Geek, Can you help me? When I first opened my pool it was green, and came clean with normal chemicals, then I noticed my steps were yellow, I was told to buy Metal and scale out, it came clean, then I noticed I was not getting any chemical readings, I had readings when I first opened it. So I took a water sample to be tested, they said I had phosphates, used a phosphate remover it went down from 300/500 to 200/300, I then put dychlor to try to get readings I put 5lbs in 18,0000 gal pool still no reading can you tell me why and what to do, also my steps are now back to yellow again. thanks nadineord

[chem geek]

Get your own good test kit.

Don't use Dichlor unless your Cyanuric Acid (CYA) level is too low.

If your CYA is high (80 ppm or more), do a partial drain/refill to lower it.

Add chlorinating liquid or bleach or if your CH is low then Cal-Hypo to shock the pool. How much, I can't say since I don't know your CYA level. Use The Pool Calculator and read Defeating Algae.

It may be that your metal out product had a reducing agent as well as a sequestrant and the former will consume chlorine so keep adding chlorine until you get a reading BUT note that if you are using a DPD chlorine test (the one that turns pink/red that you compare to a standard) that it can bleach out above 10 ppm FC.