Adding chlorine to a SW pool

[Redbull]

...OK, before I get blasted...

Our SWG has died. We have a Zodiac Clearwater LM2-24. The superchlorinate button has been staying lit since we opened the pool and none of the buttons are responsive. My spouse phoned the help line and they told him to do a "reset". He tried to reset the system and it won't even turn on anymore. The housing has split open. A few calls to pool stores have us thinking that it is dead. It is about 5 years old (we didn't install it, but moved into the house 2 years ago).

In the meantime, the kids want to swim. I know I need chlorine, but have no idea what to do! The previous owner had left some dichlor pucks (not sure what she was doing with them), but I don't see a dispenser. I usually use liquid chlorine to shock. If I use liquid chlorine as my source, how will I know how much liquid chlorine to add? Do I just dump it in the pool water daily? If I were to use the pucks do I have to buy a dispenser or could I use a make-shift device? FYI, my CYA is low (at 20), so perhaps I'm OK to use the the pucks for a bit, I think, to help to raise CYA.

We **hope** to get a new SWG in the next week or two -- we're just doing research and getting quotes...

Thanks in advance for all your help! My numbers were stellar last week, with a crystal clear pool. I want to keep it that way!

 

[Richard320]

If you want to use pucks without a floater, you can put them in the strainer, but then you have to keep the pump running 24/7.

You seem to have a grasp of the basics - you know you have low CYA and know what to add to raise it. As an aside, that low CYA cost you a lot of lost FC and made the SWG run harder than it had to.

All you need to do is measure FC. Plug that into Pool Calculator and put what you want the FC to be. Enter the size of the pool. It will do the math and tell you how many ounces of chlorine to add. Be sure to enter the strength correctly!

 

[JasonLion]

If CYA is indeed low you can use the tablets for a while, but without a dispenser that will be problematic. You could purchase a simple floating dispenser.

The simplest thing to do is probably to add liquid chlorine daily. The amount to add depends on several things, the FC level at the time, what your CYA level is, how large your pool is etc. You can calculate the amount using the Pool Calculator. If you post a full set of water test results we can help you get started with that.

 

[Redbull]

As an aside, that low CYA cost you a lot of lost FC and made the SWG run harder than it had to.

I know that now... sigh... When we first moved in, we really didn't realize what we needed to do to keep our pool water in check the first year. To be honest, I don't think we added anything at all and we only had our water tested by a pool store 2 or 3 times that year who just said our water was "fine". At the end of the season last year I discovered this forum and bought a test kit. Our CYA was zero and pH very high. I added some CYA at the end of the season, prior to close last yeat, but didn't want to add too much since we needed to drain a bunch of water to winterize and we had gotten over the heat of the summer. It was my mission to do better this year.

Last week, IIRC, our FC = 3; pH = 7.4; TA = 70; CYA = 20. At that time, I placed some CYA in a sock in the skimmer to start to bring it up (a little at a time), but have been waiting to retest. I'll post new results later tonight.

 

[Redbull]

OK, I just finished testing:

FC = 0
CC = 0
pH = 7.8
TA = 90
CH = 310
CYA = 30

The water looks OK, but not great. I can see the bottom of the deep end, but it doesn't have the nice sparkle I've had in the past. It seems dirty on the sides, my husband vacuumed a week ago. So, I decided to shock. I added 2.3 gallons (approx 9 L) of 10.8 % chlorine, brushed down the sides and will re-test in the morning. In the meantime, I'm prepping more CYA to add in a sock in the skimmer. To be honest, I'm hesitant to let my CYA get too high, as I think I will need to shock frequently (we have three little kids and lots of friends come to visit our pool) and don't want to have to use gallons and gallons of chlorine each time. I think I'm aiming for a CYA of 50. Is that reasonable?

The good news -- our SWG seems to be working! I pushed the power button and it turned on. I'll monitor it and the chlorine levels for the next few days to make sure it is actually producing chlorine 'cause it may be on the brink of extinction...

 

[JasonLion]

Once you get thing setup and working it is extremely unusual to need to shock a SWG pool. Lower CYA levels mean the SWG needs to run longer, and thus won't last as long. Lower CYA levels also mean more variation in the FC level over the course of the day, which increases the chance of there being problems that might lead to needing to shock.

 

[Redbull]

Once you get thing setup and working it is extremely unusual to need to shock a SWG pool. Lower CYA levels mean the SWG needs to run longer, and thus won't last as long. Lower CYA levels also mean more variation in the FC level over the course of the day, which increases the chance of there being problems that might lead to needing to shock.

Last year we had two episodes of a friend's child pooping in our pool. We didn't have to shock that much, other than that, really -- we had two pool parties (for my children), and shocked after those. The kids have fun with their friends over to swim, so it's the price I pay.

Do we need to shock after peeing? We have an infant who isn't toilet trained, too.

So, is a CYA of 50 reasonable? My FC this morning was 9 (last night was 10) and CC was 0.5. Hopefully we can get all set up properly this year.

 

[chem geek]

Do we need to shock after peeing? We have an infant who isn't toilet trained, too.

So, is a CYA of 50 reasonable?

You do not have to shock after peeing since it's relatively sanitary and chlorine just needs to oxidize the ammonia and urea in it, but you do need to see if the FC is dropping too much -- if it is, then add more chlorine to maintain your appropriate FC level for your CYA level. It's fecal matter that is more of a problem and needs higher chlorine levels to be sure to kill everything off more quickly (though even then, it's more for assurance than anything else -- chlorine still kills fecal bacteria quickly -- it's just that they tend to be more clumped together in fecal matter and the quantities are high and there is the small risk of having protozoan oocysts that are more chlorine-resistant).

A CYA of 50 ppm is reasonable for a manually dosed pool. You can just see how your daily chlorine demand goes -- if it's high due to a lot of direct sunlight, then you can consider a higher CYA level; otherwise, just leave it as is.