No Chlorine and No CYA using FAS-DPD? Possible?

[burrben]

I'm very new pool owner, and I just opened up my pool about 3 weeks ago. It had lots of green alge from the winter, so I dumped about 6 jugs of chlorine in it, ran the filter 24/7 cleaning it each day (cartridge), and vacc'd it each day. It got nice and clear.

So today I decided to do my 1st test of the new season (I'm very inexperienced with FASDPD) and I do my ChlorFree CombChlor test. I added 3 scoops of R870 to a 10ml sample. No color.

I then tested the CYA to see if it's really high and eating my chlorine. I used R-0013 and 7ml of pool water to fill to the 14ml mark and it's totally clear. No color.

PH measured a little above 8.0.

I'm confused. There is some algae forming in my pool now, so I'd like to add clorine tonight.

I have baking soda and borax at home along with 3 jugs of liquid clor.
It's a 6000gal bean shaped fiberglass pool with a cartridge filter.

Any advice is appreciated!!!!

 

[AprilNC]

If you added 6 jugs of chlorine 3 weeks ago and nothing since - then yes it is absolutely possible that you have 0

You need to read pool school and run a full set of tests.

And welcome to the forum - there are lots of very knowledgeable people here that will help!

 

[Smykowski]

April's right. Start with the link in my signature.

 

[JasonLion]

With CYA at zero, you will lose all of your chlorine to sunlight each day.

 

[burrben]

Ok, thanks all. I did read through the threads when I bought my house with the pool. The previous owner used pucks and my CYA was so high that I had to add tons and tons of chlor to take effect. I guess I have the reverse problem now. With the CYA at zero, now I understand why I'm using lots of chlor!

So should I start by getting my CYA right, and then focus on PH and TA? I don't want to overdo it in CYA since it's really $$ to empty and refill.

 

[JesseWV]

Is the water from the previous owner still there or was it drained and refilled?

 

[BoDarville]

So should I start by getting my CYA right, and then focus on PH and TA? I don't want to overdo it in CYA since it's really $$ to empty and refill.

Job One is to clear your pool of algae. Here's what I recommend:

1. I would first add enough CYA to get to around 30 ppm. For your 6,000 gallon pool, PoolMath recommends adding 24 oz by weight or 25 oz by volume of granular stabilizer (CYA). Add the CYA to an old gym sock or similar implement and tie it off. Since you will be running the pump 24/7 until the pool is clear, you can either hang the sock in front of a return jet or place it in the skimmer. It may take a couple of days for the CYA to dissolve, but once you initially add it you can assume it's all there for chlorine dosing purposes (see Step #3).
2. Adjust your pH within the range of 7 - 7.5. Once it's in this range, you can begin the SLAM process. Once you begin the SLAM, do not test or adjust pH until the SLAM is done and FC drops below 10ppm. Don't even concern yourself with TA at this point.
3. Dose your pool with 12 ppm chlorine . This is the SLAM level for a pool with 30 ppm CYA, per the Chlorine/CYA Chart. For your pool, you will need an initial dose of 109 oz of 8.25% bleach.

Once you begin the SLAM, you will need to test FC several times a day to make sure that FC stays as close to the target of 12 ppm FC as possible. The 12 ppm SLAM-level FC is a target, not an absolute minimum. FC can go slightly above or below this target. However, the closer you maintain FC at the target of 12 ppm, the quicker the SLAM process will go and the quicker your pool will clear. Use the PoolMath tool to determine how much bleach you will need to add for subsequent doses.

 

[JesseWV]

It's still important to know if you did a drain/refill!

You said the previous owner used trichlor tablets and there was a high CYA level. What was this high level?
You said you recently got a result of 0 for CYA, but CYA doesn't go away over the winter.

There are two possibilities:

1. You drained and replaced over 80% of the water. At an original CYA level of 100 or less, this would put you at 20 or less. This could still be read as 0.
2. You did NOT drain and refill. All of the CYA was converted to ammonia over the winter.

 

[burrben]

I did drain and refill my pool last year and after the re-fill my CYA reading was 40. But that was about 6mo ago.
This is the first time I took a CYA test in 2014.

 

[JasonLion]

It is possible for CYA to vanish over the winter.

 

[tommyd123]

I ran into the disappearing cya problem with my parent's pool, so is you expected a cya reading, have done the test correctly, and not replaced a significant amount of water, your cya could have been converted. You will know that is the case if you do the fas dpd test and your cc's are very high.


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[burrben]

Well, I did a FC, CC and CYA test again. All 0. So either something is messed up in the test kit, or I really have *just* water.
I added 2.5lb or 40oz of CYA today in a sock in my filter basket.
Thanks again for the help. I'll post results in a few days.

 

[Casey]

Recheck the CYA in a week.

 

[KrisIL]

April's right. Start with the link in my signature.

The link in your signature doesn't work. I click on it and nothing happens.

 

[Beens]

http://www.troublefreepool.com/content/123-abc-of-pool-water-chemistry

I'm pretty sure that's what it is supposed to be linking to!

 

[chem geek]

I did drain and refill my pool last year and after the re-fill my CYA reading was 40.

There is no CYA in fill water so if it was a complete drain and refill the CYA should have been zero.

As for your zero reading now, even if bacteria degraded the CYA over the winter, you could be lucky and not have a high chlorine demand from it upon spring opening. Sometimes bacteria convert the CYA into ammonia which has a huge chlorine demand -- every 10 ppm CYA degraded requires around 30 ppm FC to get rid of the resulting ammonia. Sometimes bacteria break it down all the way to nitrogen gas or nitrate and you have no unusual chlorine demand. If you tested for FC and CC and both are zero, that doesn't tell you anything unless you added chlorine first. As for CYA, it can take a while to show up in the test since it takes a while to fully dissolve. Having it dissolve in a sock over a return as you are doing will be faster than putting it into the skimmer to have it dissolve in the filter.

So you should add chlorine to the pool, wait 10 minutes or so for circulation to mix it up a bit (assuming the pump is at high speed), and then test for FC and CC. If you have no or low FC and you have higher CC, then you've got ammonia and may need a lot of chlorine to get rid of it. If you measure FC with little or no CC, then you had just plain water so should be able to hold the FC once the CYA gets into the water.