Liquid + Solid chlorine strategy

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J

John Rock

Well-known member
Apr 10, 2010
110
Montreal, Quebec
Hi,

For a couple of years now, after ditching the expensive SWG, I've been using high concentration liquid chlorine. This year, I've installed a solar heating system and since then, I've found that my need for chlorine has really spiked. With CYA around 35, I find that I need to put a 5L (10%+) jug every couple of days otherwise algae starts appearing. At 5$ a jug, it's feels expensive to me...

- Will increasing my CYA really help lower chlorine need and cost?
- Is my chlorine consumption in line with expectations? (my water temp is usually around 80-84)
- Since our season ends in septembre, should I consider introducing solid chlorine since my CYA can afford to go up and by spring during opening, my CYA typically is back to zero? If so, what kind of solid chlorine and dispensing mechanisme should I consider for a 16x32 pool with a pump running 24/7?

I don't mind keeping adding liquid chlorine, but it seems like I could maybe optimize costs and perhaps simplify upkeep a bit with a combo approach.

What do you think?

Thanks!
 
Elevating your CYA to 40-50 ppm may help reduce chlorine losses. Does your pool get full sun most of the day? Have you performed an OCLT to determine if you have a nascent algae issue that's increasing your chlorine demand? This can happen even without visible algae or excessive cloudiness. Is the water sparkling or slightly dull?

You could up your CYA directly by adding granular CYA. You could use several bags of dichlor shock or trichlor tablets over the next few weeks to elevate CYA as well. I would perform the OCLT for sure to verify you have nothing going on currently.

I go through about 2 to 2.5 gallons of 12.5% bleach every week in my 32K gallon pool, so yours seems a bit high for normal usage. I'm rather spoiled on chlorine costs here as my 12.5% is usually only $2.50 to $3.50 per gallon.
 
My pool is just slightly larger than yours and I use a little over a half gallon of 10% a day. My cya is 60 now I upped it from 40 which helped the consumption, I was closer to 3/4 gallon 10% at 40 cya. So increasing cya did help a little.

As recommended you might do an oclt to rule out algae but your daily consumption sounds to be in line with the standard 2-4 ppm daily loss.

I use pucks for cya when I need it. Best way I have found to do it is calculate how much each puck will increase your cya by then figure out how many pucks it will take to hit your cya target, set that many aside and add to pool. I'll test cya about a week after they have dissolved. I have an inline chlorinated that came with the house but I think a simple floater is the most economical.
 
Thanks for your input! The pool gets direct sunlight perhaps 50% of the day, but I have a pool cover most of the time during the week. Indeed, OCLT test would be a good idea to make sure I'm not dragging some kind of issue. I'll do this tonight.

It seems like I'm using perhaps 33% more chlorine than you, but mine is probably weaker as well, which maybe accounts for a part of the difference. Can you confirm what is your target CYA level?
 
I recently upped my cya from 40 to 60. It slightly helped the daily consumption. But this is personal to your pool, I find 60 works better with our south Texas sun.

Check the dates on your bleach. Mine is very fresh always less then 30 days old so I might be closer to 11% or even 12%.
 
Yep that's pushing it. You could go buy one jug of fresh stuff and see if it requires the same amount as what you bought in may. Or about thirty minutes after your addition test again and see if you hit your target.
 
Ok, so after sun down I tested my water. Chlorine was at 5, PH at 7.6 but CYA under 30 now. I did loose a lot of water lately because of a broken return valve I'm looking into.

I added 6 cups of 10.8 liquide chlorine and now I'm at 10. I'll check the level first thing.

Since the CYA is low, I added what I had left. Seems like I'm always missing some. I added at least 30$ worth since the beginning of the summer. Wouldn't using powder chlorine until my CYA reaches the target level would be a logical choice, since I would be getting the CYA for "free" with the chlorine? What am I missing here? :)
 
You can use whatever method of chlorinating you like - the forum just advocates knowing what you add and how that effects your water.

Be sure you are placing CYA powder in a sock and hanging it in front of a return, such that it does not rest on liner. That is be best way to be sure the CYA powder is fully dissolved.

Take care.
 

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mknauss said:
You can use whatever method of chlorinating you like - the forum just advocates knowing what you add and how that effects your water.

Be sure you are placing CYA powder in a sock and hanging it in front of a return, such that it does not rest on liner. That is be best way to be sure the CYA powder is fully dissolved.

Take care.
Click to expand...

That's funny. I always do that but just this time, I followed the instructions by sprinkling it. I thought maybe my CYA was getting stuck straight in the filter and that's why my numbers were low. Guess not!
 
John Rock said:
That's funny. I always do that but just this time, I followed the instructions by sprinkling it. I thought maybe my CYA was getting stuck straight in the filter and that's why my numbers were low. Guess not!
Click to expand...

If you sprinkled the CYA powder in your pool directly, the granules can bleach out your vinyl liner. Brush them around now. Always use the sock method. It will not get caught in your filter if you dissolve it in front of a return jet.
 
mknauss said:
If you sprinkled the CYA powder in your pool directly, the granules can bleach out your vinyl liner. Brush them around now. Always use the sock method. It will not get caught in your filter if you dissolve it in front of a return jet.
Click to expand...

Wow if that happens, the pool store will have an ear full given the sell the product with those instructions

- - - Updated - - -

So my FCCcv this morning is around 7.5, so it looks like I need to Slam after all. Perhaps that's been the reason of my perceived high chlorine consumption. Since I need CYA anyways, I will try using some pucks in addition to liquid chlorine.

Those anyone have a device recommendation for efficiently using pucks for a 16x32 pool? This will also be useful for when I have to leave for a couple of days on vacation.
 
John:

Your chlorine consumption is high. A couple of thoughts.

1) Your % of bleach may not be accurate. Please check the date. It also depends on where the bleach was stored, even for 30 days in hot weather could cause problems.

2) When are you adding the bleach? What time of the day, evening, etc? Always add real early or real late. I keep my CYA at a very low and burn off very little.

3) Is there a lot of activity in the pool (swimmers, etc.?) or do you have a lot of debris dropping in the pool? Or does the pool stay relatively clean?

Outside of this, a SLAM is in order. Once you complete the SLAM, then you can follow dosing real early or real late. You may also want to switch to the generic 8.25%, instead of 10%. Where exactly are you getting the bleach?
 
1) I'll check to see if I can see a date on the jug. Given that I went from 5 FC to 10 in a standard 16*32 pool after adding 6 cups of liquid chlorine, could a calculation confirm my chlorine %?

2) I always add it late evening when the sun is down

3) Activity is high on the weekends, not so much in the week... Maybe used 2 times on average in the week. I don't have that much debris, but many trees and pollen I think. I've been battling some kind of algae. Initially in June I came to realize it was maybe pollen but now I think it's algae. Pool wasn't clean last night when I added the chlorine I must say.

I've been buying the bleach at a national canadian retail store called Canadian Tire. I haven't found a cheaper source elsewhere. It's currently 5.30$ CA for 5 liters.
 
For 1 yes you can use pool math to calculate an addition add it then after 30 mins of pump running test again to see if you hit your target. Assuming the volume you used in pool math is correct this will tell you if your bleach is as strong as you think it is. This isn't a perfect test but you'll know if the bleach is way under strength. Also do this in the evening after sun is off the pool so the sun doesn't burn any.
 
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