Should I raise my cya?

[gmh757]

Hi all. I'm new to posting, so bear with me! I have a 22000 gal pebble-tec pool. The water temp is 90 and getting lots of Phoenix summer sun.

Here are my numbers from this morning.
ph- 7.6 fc- 3.5 ta- 50 ch- 725 cya-45

I'm having to add a gallon of muriatic acid and a gallon of 10% sodium hypochlorite chlorinating liquid every 4-5 days, sometimes even after 3 days.

Would raising my cya stabilize the ph so I don't have to add the chlorine so often. Also, it seems that my adding so much acid lowers my ta, but when I raise the ta, my ph shoots up.

And lastly, the water in Phoenix is very hard, but is such a high ch acceptable?

Thanks

[Watermom]

Raising CYA will not affect your pH.

How are you raising TA?

CH of 725 is very high but if your fill water is that high, there's not a lot you can do about. However, you will want to keep your TA and pH on the low end.

[PoolDoc]

I think you're looking that the chlorine use as excessive, but . . .

1. Chlorine consumption increases with the water temp for a variety of reasons, including chlorine reacting with the CYA

2. It's quite likely your 10% bleach . . . isn't. Try switching to 8% bleach, purchased from Walmart, where it's stored in a air conditioned area. I think there's a good chance you'll find you get more chlorine from the "8.25%" than from the "10%"

Commercial 10% bleach, shipped at 12%, and stored in a pool wholesale warehouse at 100 degrees (Phoenix) for a month, may arrive to your pool at 6%, or even less. Walmart bleach, shipped to AZ a week before purchase and stored in an air conditioned store may arrive at your pool at 9%.

This is why it's NEVER a good idea to 'stock up' on bleach -- it just doesn't keep at high temps.

If you want to lower your CH, it's possible, but messy. If you aren't having problems with your pH bouncing around, and don't have a heater or salt system, you may want to leave it alone.

[gmh757]

Hi Watermom. Thanks for a quick reply.

My bad on the pH. I meant would raising the CYA stabilize the FC without messing up the chemical balance of the pool. I was thinking about raising it to around 60.

I have used "Alkalinity Up" to raise the pH. My test kit (TF-100) and other things I've read say I should keep the TA between 100-120, but when I add the Alkalinity Up, it takes quite a bit of Muriatic Acid to bring the pH back down to an acceptable range. Now I'm reading that if I have a high CH, I should keep my TA and pH lower, as you said. I guess my question what be what is a good range for the TA? I'm working to keep my pH between 7.2-7.6.

I just tested the CH coming out of the faucet next to my pool equipment, and was shocked to see it was 200. I tested my pool water again, and it came up 700. Somehow it has really gotten out of whack. I just did a partial refill of my pool (50%) late last fall, so I'm baffled.

[gmh757]

I think you're looking that the chlorine use as excessive, but . . .

1. Chlorine consumption increases with the water temp for a variety of reasons, including chlorine reacting with the CYA

2. It's quite likely your 10% bleach . . . isn't. Try switching to 8% bleach, purchased from Walmart, where it's stored in a air conditioned area. I think there's a good chance you'll find you get more chlorine from the "8.25%" than from the "10%"

Commercial 10% bleach, shipped at 12%, and stored in a pool wholesale warehouse at 100 degrees (Phoenix) for a month, may arrive to your pool at 6%, or even less. Walmart bleach, shipped to AZ a week before purchase and stored in an air conditioned store may arrive at your pool at 9%.

This is why it's NEVER a good idea to 'stock up' on bleach -- it just doesn't keep at high temps.

If you want to lower your CH, it's possible, but messy. If you aren't having problems with your pH bouncing around, and don't have a heater or salt system, you may want to leave it alone.




Thanks PoolDoc. I guess those 7 gallons of chlorine sitting in my garage aren't the best idea! As far as the CH, as I said in my reply to Watermom, the CH in the pool is significantly higher (700) than what comes out of the faucet (200). My pH is not bouncing around, but does seem to need to raise up about .015 a day. Is that excessive?

[Watermom]

So, I'm assuming you have been using some cal-hypo to chlorinate with at some point since yout CH is so high in the pool compared to your tap water. No more cal hypo!

[gmh757]

So, I'm assuming you have been using some cal-hypo to chlorinate with at some point since yout CH is so high in the pool compared to your tap water. No more cal hypo!


I'm not sure. I was using tricolor tabs before I switched to liquid chlorine about 6 months ago. I've used a couple of different products before to shock the water, so maybe there was something in those. Anyway, now I'm just using the liquid chlorine, so that won't be a factor. Thanks!

[dubbedout]

I'm in Gilbert, AZ so I'm familiar with the sun eating up chlorine pretty rapidly. My CYA is around 50-60 right now, I left for California last Wednesday and put 4 gallons of 10% liquid chlorine in on that Tuesday evening, today when I tested I was at 1ppm Cl. We also has a big dust storm while I was away but I came home to a crystal clear pool. I always store my liquid chlorine or bleach inside where it's cooler (78 degrees). I buy 4 gallons at a time and they last me about 2 weeks.

Oh and I'm also having to add muriatic acid ever so often but my fill water has very high pH, so you have to figure that into everything as well.

Where are you buying your liquid chlorine?

[gmh757]

I'm in Gilbert, AZ so I'm familiar with the sun eating up chlorine pretty rapidly. My CYA is around 50-60 right now, I left for California last Wednesday and put 4 gallons of 10% liquid chlorine in on that Tuesday evening, today when I tested I was at 1ppm Cl. We also has a big dust storm while I was away but I came home to a crystal clear pool. I always store my liquid chlorine or bleach inside where it's cooler (78 degrees). I buy 4 gallons at a time and they last me about 2 weeks.

Oh and I'm also having to add muriatic acid ever so often but my fill water has very high pH, so you have to figure that into everything as well.

Where are you buying your liquid chlorine?


Wow, you burned through that chlorine pretty fast. I seem to go through about 3.5 ppm of chlorine a day on a sunny summer day, which seems pretty high to me. I'm wondering if raising my cya to 60 would slow the FC usage without messing up the chemical balance of the pool. By the way, what is your TA?

I've been getting my chlorine mostly at Albertson's. I'll have to look to see if they are printing a manufacture date on the box. I didn't realize that it loses effectiveness in heat.

[dubbedout]

Yeah, I go through about a gallon a day I guess. I've called around to all of the local pool stores in the east valley for liquid chlorine prices and the cheapest right now is at NPS Pool & Spa Supply, 2 gallons of 10% for $4.95 (sale going on till end of July).

Here's a breakdown of price per oz that I made up:
http://i.imgur.com/ceT9IV5.png

[PoolDoc]

Keep in mind that bleach at Sams or Walmart is likely to be fresher, and cooler, than bleach at a pool store. Take a look at their tank -- if its black poly, in the Arizona sun, it's VERY unlikely that it arrives at your pool at the rated strength.

Another test is to 'take the temperature' of the bleach just after buying it. If it's above 90 degrees, it may be 4% bleach.

But the best test -- if you have a K2006 -- is to dose the pool with equal doses of the various bleaches, in the late PM and test the pool FC level just before, and an hour after, dosing.

[dubbedout]

Yeah, I understand that most of the bleach/LC is trucked in and loses some strength. Most stores keep their supply indoors at least, except for one store I ran into that keeps it sitting outside in the "shade". Unfortunately, that store is the only place that sells 12.5% and you return the empty bottles and get new ones.

I'll have to try that testing though, I've just been trying to cut down on all the waste with all the bottles and boxes which is why I switched to LC.

[PoolDoc]

Let us know what you find.

(If you get really curious, I can tell you how to directly test bleach % -- but you'll either have to buy some accurate pipettes or a bleach kit.)

[Tom.B]

DANG!!! Just saw this and I had no idea bleach looses its strength! Just went to Wal-Mart over the weekend and about 14 gallons. Now have 17 in the pool shed. So much for BBB saving me money :-( (in jest... kinda) Its only been out there a few days. Can I bring them inside and "save" them? Can I test the strength? Been a cool week so far, but the last batch has been in there for a while. The shed is wood and probably not been in the 90's, however, I can't confirm that.

I was so trying to keep from going for bleach weekly and hoped to go monthly. Bummer.

[Watermom]

Go ahead and bring them in. I buy 8-10 jugs at a time and keep them in my cool basement.

Here are a couple of ways to test the strength of bleach.

The first one was from AnnaK (one of our support team members who is no longer active on the forum.)
* add 10 ml LC to 1 L water, mix,
* add 10 ml of the mix to 1 L water, mix
* test using the 25 ml procedure multiplying the # of drops by 0.2.

------------------------------------------------------------------------------------------------------------------

Here is how CarlD (another one of mods) tests his liquid chlorine:

Put ten liters of tap water ( That's 5 soda-bottles full) in a 5 gallon bucket.

Test that water for chlorine using the FAS-DPD test to get a chlorine baseline (you may have some).

Then I take a 1 ml eyedropper full of the LC or bleach I'm testing and put it in the bucket and mix it up.

(1 ml in 10 liters of water is the same as putting 1 gallon of LC in a 10,000 gallon pool -- it's 1/10,000th. )

I then measure the bucket with the FAS-DPD test just like pool water. Of course, subtract any chlorine you measured in the tap water.

I use a glass eyedropper so it will hold up. Pharmacies sell them.

[amillionpets]

I just read through all of this because I was wanting to know the answer to the initial question as well. Maybe it was in the thread and I missed it? So, should I raise my CYA to keep the FC from dropping so quickly? It seems I am adding a lot more bleach this Summer than last. My CYA is 40. If I raise it to 60 will that help stabilize the FC level a little longer?

[Watermom]

Why don't you try raising it to 50 first before deciding to go to 60. You can always add more CYA but can't remove it. You may find that 50 works better. If not, easy enough to add more.

[PoolDoc]

The best info we have at the moment is that -- generally speaking -- if you run your chlorine at 10% of your CYA level, you will lose about the same chlorine, regardless of levels. Put another way: you'll lose about the same amount of chlorine daily if you maintain FC=3 if your CYA=30, as you will with FC=8 and CYA=80.

However, there is some unconfirmed information that suggests that you will lose less at very high FC/CYA levels (FC=15; CYA=150). But even if that info is correct, the improvement is not huge.

[amillionpets]

Ah! Thank you both very much! That is very interesting, Pool Doc, as I did not know that. So! I guess it's just a bleach adding Summer. ;) That's okay, though, because the water is sparkling clear! Now, if I can just keep the birds from pooping around the rim...............

[PoolDoc]

Now, if I can just keep the birds from pooping around the rim...............

You could try this:

http://kittybloger.files.wordpress.com/2011/11/cat_in_bath13.jpg

[amillionpets]

Ha ha ha ha ha!! I have several of those & that's what they'd look like if they were in the pool. Ah! Maybe a battery powered cat?? LOL

[Watermom]

That is a great picture! I'm still laughing about it.