Just RO'd my pool, trying to get it to hold chlorine...

[mantelo]

Hello everyone, I'm excited to now be a member after learning so much from this group!

I just RO'd my pool here in southern California because the CYA and CH levels were through the roof. Now I'm in the process of getting all my chemicals balanced, but I'm having a hard time maintaining a FC level.

My numbers yesterday afternoon.
FC = 7
CC = .6
Ph = 7.7
TA = 120
CH = 450
CYA = 70 in ambient sunlight, 50 in bright sunlight (trying to read the black dot)
Temp = 88F
Capacity = 9,000g pebbletec

Today my FC is zero. How do I keep it from dropping that much in one day?

I've read MANY posts trying to grasp the issue, but I'm not sure what my process should be to get it up and keep it up. I realize adding bleach daily may be necessary, but it took around 3 jugs & 6% probably to get it to that point.
A. Is it feasible that I should have to add that much daily?
B. What should be my plan of attack here?
C. Is this a case where I'm on the verge of an algae bloom and I need to shock it?

Thanks for the wonderful advice!
J

 

[Agent99]

What test kit are you using, if any, to get your numbers?

If you are getting your numbers from the pool store, they have been found to be very unreliable and inaccurate.

There are two recommended kits: Taylor K-2006 and the TF-100. See tftestkits.net

Until then, it can be hard to figure out what is going on with your pool but it sounds like you might have something in your pool that is using up the FC (free chlorine) and you might need to SLAM your pool.

 

[Texas Splash]

J, as Chris stated above, the "right" test kit is priority #1. If you don't already have either the TF-100 or Taylor K-2006, you can get it at TFTestkits.net. As for your questions:
- Adding 3 jugs may be excessive, although we don't know anything about your pool. Please add your pool info to your signature by going to the top of the TFP web page (just under the Pool School button) and select "SETTINGS". On the next page look to the left for a menu bar that says, “MY SETTINGS” and go to "EDIT SIGNATURE" to enter your pool and equipment info there. It will help us later.
- Everything you asked will be based on the true CYA reading from your own test kit. It will drive how high your FC should be at all times. CYA and CH are manageable, even in your area, but only with the right test kit.

One last thing about CYA testing:

Proper lighting is important for the CYA test. You want to test for CYA outside on a sunny day, but keep the skinny view tube in the shade. Taylor recommends standing in the sun with your back to the sun and the view tube in the shade of your body. Use the mixing bottle to combine/mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then mix again. Then, while holding the skinny tube with the black dot at waist level, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. After the first test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate the CYA reading.

Hope this helps. We'll watch for updates to assist further.

 

[mantelo]

What test kit are you using, if any, to get your numbers?

If you are getting your numbers from the pool store, they have been found to be very unreliable and inaccurate.

There are two recommended kits: Taylor K-2006 and the TF-100. See tftestkits.net

Until then, it can be hard to figure out what is going on with your pool but it sounds like you might have something in your pool that is using up the FC (free chlorine) and you might need to SLAM your pool.

I'm using the Taylor K-2006 kit.

 

[Texas Splash]

Very good. Then you need to find out what's eating-up your FC. IT's either sun or algae. My guess is you have some organic material in the water based on the amount of bleach being used and a slightly elevated CC reading. To confirm you could do an OLCT.

When performing the OLCT, remember that it must be done when the sun has dropped – no sunlight on the pool. About 8 hours total is recommended. Also, your FC level should be elevated more than normal. If you have a SWG, turn it off. Starting (bedtime) FC could be close to your SLAM level, but no lower than 10. Anything less and you may not receive an accurate portrayal of FC loss (by percentage), even if it’s only 1 ppm.

Remember to use the notes above to validate your CYA. That's critical. If you fail the OLCT, then you know you need to do a "SLAM" via Pool School - SLAM - Shock Level And Maintain.

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Please try to update your signature with your pool info at your next opportunity. It helps with our responses.

 

[Catanzaro]

A few questions:

Q: Yesterday afternoon? What time did you test? After the test, did you add any bleach @ 6%? Or did you add the bleach first, and if so, how long afterwards did you test. Where did you purchase the bleach? Most bleach is 8.25% these days unless you are purchasing pool strength at 12.5%. Maybe the bleach is not as strong as one may think. What is the date on the bottom of the jug, and assuming it is 121 fl. oz. Please provide information if you have it.

Q: What time did you test today to get to the "zero" chlorine level?

Here is what I would suggest. Add enough bleach, like you have and 45 minutes later lest the water, including combined chlorine. Then every 2 hours, during the daytime test again, repeating 3-4 times throughout the day. Then you will have approximately 5 readings for the day to determine if and how quickly you are consuming chlorine. Although we need to make sure that the 3 gallons of 6% bleach additions have registered on the test.

If you loose all your readings in the first hour or so, this could be ammonia (probably not), otherwise you have something lurking in the water and a SLAM is the next step.

If you are loosing that much in a 24 hour period (I am figuring your pool) to have increased 19 ppm. That is a lot.

 

[Isaac-1]

One other possibility here, you said you just did an RO treatment, RO membranes are very sensitive to being damaged by Chlorine, so people that do RO treatment add Chlorine neautralizer into the pool, many also add algaecide to keep the pool from going green in the process. Both of these may be causing increased Chlorine demand until they get burned off.

 

[duraleigh]

C. Is this a case where I'm on the verge of an algae bloom and I need to shock it?

That's almost correct. You need to SLAM it. read "SLAM" in Pool School. You must follow that article to a T and your chlorine consumption will be greatly reduced.

Do you have an SWG? What does your water look like?

 

[Divin Dave]

What Duraleigh says. C is the case.

with CYA of 50-70, there is no way you should loose 7ppm in a day unless organics are consuming it.

Do not SHOCK the pool by using powerder or granular shock. Any type of granular, powder or solid chlorine product with add either Calcium or CYA to your water. Neither of which you can stand to have any higher.

Use Only Liquid Chlorine and SLAM the pool. Its a process, not a one time thing. And it is not difficult to do. Very very easy.
1. Lower pH to 7.2
2. Raise FC to SLAM level (which is 40% of your CYA level).
3. Maintain the FC SLAM level. That means testing and adding chlorine several times a day, every single day, until the SLAM is finished.
4. Backwash or clean your filter when the pressure rises by 25%
5. Brush the pool once a day.
Pool School - SLAM - Shock Level And Maintain

The routing multiple times a day is:
a. Test water for FC
b. Use pool math to determine how much liquid chlorine to add. http://www.troublefreepool.com/calc.html
c. add it

The more times each day you can test and add chlorine, the faster it will go.

 

[mantelo]

One other possibility here, you said you just did an RO treatment, RO membranes are very sensitive to being damaged by Chlorine, so people that do RO treatment add Chlorine neautralizer into the pool, many also add algaecide to keep the pool from going green in the process. Both of these may be causing increased Chlorine demand until they get burned off.

They did use a Chlorine neutralizer and did not use an algaecide.

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That's almost correct. You need to SLAM it. read "SLAM" in Pool School. You must follow that article to a T and your chlorine consumption will be greatly reduced.

Do you have an SWG? What does your water look like?

I do not have an SWG and my water is crystal clear.

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Thank you everyone for all the help! I will be doing an OCLT and then SLAM based on results.

 

[mantelo]

I did an OCLT last night... Dropped from 13ppm to 3ppm.

The RO company did use a neutralizer, but that was last Thursday, so I can't imagine it is still in the system enough to drop that much?

So I will SLAM.

THANKS again.
(will update my sig with pool details)

 

[Texas Splash]

mantel, that is a significant drop in FC overnight. As you prepare to SLAM, I would recommend the following:
- First, make sure your pH is at 7.2 BEFORE raising your FC level
- Then perform the next series of steps as follows to ensure there is nothing else in the water aggressively consuming your bleach:
1. Begin a SLAM and dose FC up to SLAM level. Do not add additional CYA at this point.
2. Retest FC at 10-minute intervals.
a. If FC loss is greater than 50%, add FC to bring back up to SLAM level and continue retesting FC @ 10-minute intervals.
b. IF FC loss is 50% or less, add FC to bring back up to SLAM level. Go to Step 3.
3. If CYA is below 30 ppm, add enough CYA to bring level up to 30 ppm.
4. Continue SLAM as directed in the SLAM article until the SLAM Criteria of Done are met. Test as directed in the SLAM article - no longer need to test FC at 10 minute increments at this point.
Those instructions are very important to ensure you can maintain the FC required without interference. Once your FC holds, your SLAM should go very well. Make sure you follow everything notes on the SLAM page (link below) too! Good luck!

 

[mantelo]

mantel, that is a significant drop in FC overnight. As you prepare to SLAM, I would recommend the following:
- First, make sure your pH is at 7.2 BEFORE raising your FC level
- Then perform the next series of steps as follows to ensure there is nothing else in the water aggressively consuming your bleach:
1. Begin a SLAM and dose FC up to SLAM level. Do not add additional CYA at this point.
2. Retest FC at 10-minute intervals.
a. If FC loss is greater than 50%, add FC to bring back up to SLAM level and continue retesting FC @ 10-minute intervals.
b. IF FC loss is 50% or less, add FC to bring back up to SLAM level. Go to Step 3.
3. If CYA is below 30 ppm, add enough CYA to bring level up to 30 ppm.
4. Continue SLAM as directed in the SLAM article until the SLAM Criteria of Done are met. Test as directed in the SLAM article - no longer need to test FC at 10 minute increments at this point.
Those instructions are very important to ensure you can maintain the FC required without interference. Once your FC holds, your SLAM should go very well. Make sure you follow everything notes on the SLAM page (link below) too! Good luck!

In the process of SLAMming...

Two questions:
1. Is there any chance my CYA level could/would/should drop in this process? I feel like it has, but getting that reading is such a gray area I feel like...
2. Is there a ballpark amount of time the SLAM should take? I'm just hitting 24hrs now...

Thanks in advance!

 

[jagger2005]

In the process of SLAMming...

Two questions:
1. Is there any chance my CYA level could/would/should drop in this process? I feel like it has, but getting that reading is such a gray area I feel like...
2. Is there a ballpark amount of time the SLAM should take? I'm just hitting 24hrs now...

Thanks in advance!

Your CYA should not change unless you remove water by backwash or splash out. No real ball park on time. I would think that since you started with clear water, it will be relatively fast. How often have you been able to check the FC? and has it finally started to hold between tests?

I noticed that you recorded your original CC at 0.6
The taylor kit has instructions to use a 25 ml sample. To save reagents, you can use a 10 ml sample for FC/CC tests and multiply by 0.5 instead of 0.2
And since you are probably testing at high FC levels anyway, personally, I would do a 5 ml sample and multiple by 1. Less accurate, but when you are SLAMMing at FC 20+, you should be alright

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And welcome to TFP!

 

[Catanzaro]

In the process of SLAMming...

Two questions:
1. Is there any chance my CYA level could/would/should drop in this process? I feel like it has, but getting that reading is such a gray area I feel like...
2. Is there a ballpark amount of time the SLAM should take? I'm just hitting 24hrs now...

Thanks in advance!

Please add your signature as this will be easier to answer questions:

Pool School - Read This BEFORE You Post

Your CYA could drop if you replace a lot of water during the slam.

There really is not a ball park amount of time a SLAM should take. Some take a short period of time, while other's last a lot longer.

Your SLAM is complete, when the following 3 items have occured:

CC is 0.5 or lower, You pass an OCLT (overnight FC loss test shows a loss of 1.0 ppm or less over a 8-10 hour period), and your water is clear.


Pool School - SLAM - Shock Level And Maintain

 

[Cinic]

This thread got me looking into RO for my medium high CYA. I came across one website from an area company that stated: "Additionally, please do not add any chlorine, algaecide, or shock to your pool for the 2 weeks prior to our service." Man I'd have a hard time doing that.