Help with CYA levels

[Thehobe]

Split by moderator from HERE. Please start a new thread to ask your own questions and not hijack other member's threads, especially 3 year old ones. Thanks, jblizzle

My CYA levels are also very high and unfortunately, due to the water shortage and the draught here in California, I cannot dump half of the water in the pool right now. Even after adding 16 gallons of 10% Chlorine over the last 2 weeks, my free chlorine quickly drops to 0 every morning. The pool math calculator says I would need 30 gallons of 12% chlorine to get the FC up to a reasonable level(25,000 gal pool and spa). I have been also adding Calcium Hypochlorite to keep the algae away.
If I do ever get some FC to read after nightfall, I would assume that with water exchange and backwashing, as my CYA goes down, the bound up chlorine will be released somewhat (except for the amount lost during backwashing of course) due to the now lower concentrations of CYA. Is this true?
I will avoid ever using a stabilized chlorine product in the future (Leslie's ChloroBrite).
What is the power consumption rate of a SWG cell system? This may be cheaper than liquid chlorine even after the expense of the system, salt and running costs!

 

[pwrstrk]

Re: what's so bad about high CYA levels?

What is your CYA level and your CH level ? What test kit are you using ?

 

[Thehobe]

CH is 300 and CYA is 140. That is from Leslie's report yesterday. The only chlorine test that I see Chlorine greater than 3 is when I wait a couple of minutes using the small OTO reagent. I assume because I have to wait for the solution to turn yellow that is because I am actually looking at the combined chlorine but I do not know how to interpret delayed color change to bright yellow.

 

[jblizzle]

Obviously the first thing you need to do is invest in one of the Recommended Test Kits and post up some more believable numbers.

Assuming the CYA of 140ppm is correct, which I doubt, then you need to maintain a MINIMUM FC level of 11ppm and your shock level for the ShockLevelAndMAINTAIN Process would be a FC of 55ppm.

You should stop using cal-hypo as well or your CH is going to go up, which will also point to needed a water change.

 

[singingpond]

My CYA levels are also very high and unfortunately, due to the water shortage and the draught here in California, I cannot dump half of the water in the pool right now. Even after adding 16 gallons of 10% Chlorine over the last 2 weeks, my free chlorine quickly drops to 0 every morning. The pool math calculator says I would need 30 gallons of 12% chlorine to get the FC up to a reasonable level(25,000 gal pool and spa). I have been also adding Calcium Hypochlorite to keep the algae away.
If I do ever get some FC to read after nightfall, I would assume that with water exchange and backwashing, as my CYA goes down, the bound up chlorine will be released somewhat (except for the amount lost during backwashing of course) due to the now lower concentrations of CYA. Is this true?
I will avoid ever using a stabilized chlorine product in the future (Leslie's ChloroBrite).
What is the power consumption rate of a SWG cell system? This may be cheaper than liquid chlorine even after the expense of the system, salt and running costs!

Here is an interesting recent thread, from someone who forged ahead with SLAM at very high CYA levels, apparently with general success:
http://www.troublefreepool.com/threads/85926-Dead-algae-settling-overnight-after-SLAM

Food for thought, perhaps.

In the short term, I don't think a SWG system can put out the kind of chlorine levels you need with your high CYA. Maybe in the long run, when CYA is under control, it may be a good option.

And please do get a good test kit, as per the link in post #4.

 

[Thehobe]

I stopped using Leslie's granular chlorine with stabilizer weeks ago and have only been using liquid chlorine and Power Powder, a calcium hypo. I will change water when California gets some more water. I'm stuck now until at least the Winter rains. It's too bad no one make a CYA reducer. Iadd a gallon of10% liquid chlorine each day that brings up the chlorine level to above 3 ppm but that is short lived due to the CYA levels locking it all up. The pool math tells me that I can use the 10 lbs calcium hypo to get the FC up to around 10 so that is my present plan. I will have to pre-dissolve so my pool does not become too cloudy. Is this at least a temporary fix until I can replace some water this winter?

 

[pwrstrk]

The problem is we don't have accurate test results to base our advice on. Accurate testing and knowing how much of what to add is the corner stone of this forum. I suggest you order the TF-100 test kit. It's the best value.
When you get the kit post up a full set of results and then we can give you accurate advice on what and how much too add. The CYA level is key as that sets your FC level. Very high CYA levels can be managed with liquid chlorine, but it will take a lot of diligence until you can get that level lowered. Again we need an accurate test on it to see exactly where it's at.
For example per pool math, if your FC was at 3 it would take 3 gallons 2 quarts of 8.25% bleach to get your FC up to 15. This is assuming your CYA is 140. Once you get it there it will take daily doseing of bleach to maintain that level. Again you need a good test kit to test high FC levels. Another downside is that having to maintain your FC level above 10 is the PH test is invalid with FC levels of 10 or more.
The test kit is going to be a small investment as compared to all the pool store chem's your using. Without it your not going to be able to manage your water.
Using the cal hypo is going to keep raising your CH. The CYA doesn't lock up your FC. It protects your FC from the sun burning it off. You need CYA, you just can't let it get out of control from using stabilized forms of chlorine. The higher that level gets, the higher FC ranges need to be to prevent algae.
Consider getting the test kit ! ?

 

[singingpond]

I stopped using Leslie's granular chlorine with stabilizer weeks ago and have only been using liquid chlorine and Power Powder, a calcium hypo. I will change water when California gets some more water. I'm stuck now until at least the Winter rains. It's too bad no one make a CYA reducer. Iadd a gallon of10% liquid chlorine each day that brings up the chlorine level to above 3 ppm but that is short lived due to the CYA levels locking it all up. The pool math tells me that I can use the 10 lbs calcium hypo to get the FC up to around 10 so that is my present plan. I will have to pre-dissolve so my pool does not become too cloudy. Is this at least a temporary fix until I can replace some water this winter?

I think there may be a misconception here -- if your measured chlorine level quickly drops from 3 to 0, that is not because CYA is 'locking it up' -- measured chlorine drops because it is used up fighting organics (as well as some rate of degradation from sunlight exposure, of course). Even if you don't have visible algae at the moment, you may have something growing in the pool, explaining rapid drops in measured chlorine. If that is the case, you'd have to raise chlorine levels even higher to kill whatever is starting to grow. Have you read Pool School (link at upper right of forum pages), and the explanation of the SLAM (shock level and maintain) process?

High levels of CYA reduce the effectiveness of the chlorine you add (by holding some of it in reserve), but high CYA levels don't prevent you from measuring all of the chlorine in the water. If you're not measuring it, it's not there.

It would probably be better to add liquid chlorine, rather than cal hypo, even if it's a pain to buy and transport all those bottles. As others have already cautioned, calcium is another material that stays in the water, and you don't want your CH levels to rise too much either. You perhaps feel disillusioned with the effectiveness of liquid chlorine, having put 16 gallons of it into the pool over 2 weeks. However, this probably means you didn't put enough in to get the upper hand over whatever is consuming the chlorine. Without accurate testing -- there's that refrain again -- you don't know how much chlorine you actually have to add. If you consistently add too little to do the job, then you can end up tossing large amounts of chemicals (and money) down the drain without making any net progress at all. If you haven't already done so, please take a look at the thread I linked earlier (a pool owner conducting a SLAM at CYA levels of 240, if I remember the numbers correctly).

As far as a CYA reducer, there are some areas of the country where you can find reverse osmosis services -- not cheap, but effective in removing calcium, CYA, and pretty much any other additives/impurities that may be in the water.

I guess another potentially relevant question is how many months you are hoping to eke out before possible water replacement (i.e. when is 'winter' in your area)?

 

[jblizzle]

I was thinking the same thing about your misconception of how the CYA works.

 

[Thehobe]

Re: what's so bad about high CYA levels?

I have a Taylor K1005 but it does not test CYA. The FC ranges from 1-3 after I add 2 gallons of 10% chlorine to the 25,000 pool and spa. The PH is 7.2 and getting a little higher after adding 5lbs of Soda ash. The Total Alkalinity is 200 according to the Taylor test kit. According to my Insta-Test strips, the CYA is approximately 150.
Leslies measured Calcium hardness of 300, TDS of 600 and Pho=0 (thanks to the use of No-Phos). I just found out that according to the Taylor test kit, adding a shock such as Power Powder, the combined chlorine will be released as well during shocking, something I was not aware of. Pool is blue but slightly cloudy resulting I assume from adding the pre-mixed Soda Ash mixture directly into the skimmer. One problem I surely have is complete mixing of the pool water in a reasonable period of time. My sand filter is also a very slow filter of any cloudiness. It take 10-15 hours to clear the cloudiness. Another question I have is how long does it take for each of these chemicals to completely dissolve in the pool before measuring with test kits?