Questions & Big Thank You

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MicheleS

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Oct 29, 2008
18
First, I'd like to thank this board for helping me make the switch to BBB. I have had to drain and refill my pool 3 times this year due to high CYA levels because of bad advice at the pool store. This last time I had to drain and re-fill 80% of the water twice in a week to get the CYA level DOWN to 100 (tested myself with a DPD test kit) so I could begin to attack the algae problem. Yesterday I began putting in 6% bleach to get the FC levels up to what the pool calculator recommended for shocking on a consistent basis. I worked on it all day yesterday and throughout the night. I woke up this morning to clear water :) :-D

Pool Info:
12,500 in ground concrete pool with Hayward pump and cartridge filter
Pool has a heater, but is currently not on until I get the water situated
Pool is in SW Florida so not closed, and since it's heated I use year-round
I am usually the only one who goes in it, but I am in it every day
Pool water was green and cloudy, but is now clear
Pump has been running 24/7, filter being cleaned daily, pool being brushed daily
Normally, pump runs about 8-10 hours a day

Most recent pool test (as of this morning):
FC = 15, TC = 15
CYA = 100
PH = 8.0 (added 20 oz. muriatic acid after test)

Some questions please:

- What are safe levels of FC for swimming (meaning no bleaching of hair or suits)?
- Based on the CYA chart, am I correct that I need to keep my FC at 12 to prevent another algae bloom?
- If I keep my FC at 12 (assuming CYA is 100), will I need to shock?
- I am going to test the PH again tonight to be sure it's gone down. If not, I'll add more muriatic acid.
- I've drained/re-filled the pool (80% each time) twice this week and am still at CYA 100. I'd like to wait a while before going through that again (my water bill will be astronomical this month)!

Thanks for any help!

~ Michele
 
Welcome to the forum!

Something is wrong with your test results. 100ppm CYA after several 80% drain and refills isn't reasonable. You want the black dot at the bottom of the tube to be completely obscured by the cloudy water in the test tube if you are using a Taylor CYA test. Either test a sample of your tap water which will be 0ppm CYA to verify your test kit, and/or take a water sample to a couple of pool stores and have them test the CYA for you. It's also a bad idea to trust pH results while the chlorine level is high.
 
Thanks John. I did take a sample to the pool store after the first 80% drain/re-fill this week and they said they said the CYA level was still at 100 (they said they couldn't test any higher than that), so when I did the second 80% drain/refill I didn't bother to bring it back, just used my test kit.

I will say that when I tested the CYA before I started re-filling the water, it was much higher than it is now because the black dot was obscured by the cloudy water well above the 100 mark and now it is right at the 100 mark.

I will test my tap water to be sure I am at 0 CYA with this test kit. I have also read that I can add 1/2 tap water to my sample and then just double the CYA reading, is this correct?

How will I be able to test the PH if I have the leave the target FC at 12?

Thanks again ~ this board is a wonderful resource!
 
Yes, with the CYA test you can mix equal parts of pool water and tap water and test that, then multiply the result by 2 to get your actual CYA level. The result is less precise than doing the test without dilution, but still acceptable for measuring high CYA levels.

Using the Taylor PH test, the PH may well read slightly higher than actual when the PH is between 10 and 15, but it will be close enough to be useful for managing your PH.

If your CYA level is really 100, you want to maintain your FC level between 8 and 13. As long as you don't have algae now, that will be sufficient to prevent you from getting algae. Since there is some uncertainty about your actually CYA level, it would be best not to go as low as 8 or 9.
 
MicheleS said:
I will say that when I tested the CYA before I started re-filling the water, it was much higher than it is now because the black dot was obscured by the cloudy water well above the 100 mark and now it is right at the 100 mark.
Click to expand...
When you said that it was higher before "because the black dot was obscured by the cloudy water well above the 100 mark", did you mean "well below the 100 mark" in the sense that it took less water to have the dot obscure before that water level reached the 100 line? See the photo in this link for the back of the tube in the K-2006 test kit or the photo in this link for the view tube in the TF100 test kit. The test is a seemingly backwards one in that lower CYA levels require you to add more water to the view tube before the black dot is obscured. So obscuring with a little water means a lot of CYA and vice versa.

Richard
 
Sorry about that - I meant "well below the 100 mark" as the tube in the TF100 tube kit shows. The second reading required more water to obscure the black dot, but it was just at the 100 line rather than being well below.

Is it possible that two 80% drain/re-fills this week are still showing this high of a CYA level? I have not put any stabilized chlorine products in the pool since the first drain/re-fill this week. I have only used 6% unscented chlorine bleach to get the FC level up to shock level and maintain it there until the water was clear and not losing more than 1 ppm of FC overnight (which happened as of this morning).

Tonight, I'll need to add more liquid chlorine (6%) to keep the FC at a target level so I'm trying to be sure I am using the appropriate target based on my CYA level.

Any suggestions would surely be appreciated as this is my first experience with BBB and I have been reading this site like crazy trying to be sure I get everything right.

Thanks again!
 
If you replaced 80% of the water twice, or to put it another way, replaced nearly all of the water twice, then the CYA level would be 4% of what it was originally. For the CYA level to have ended up at 100 after two 80% replacements it would have had to have been 2500 to start, which is difficult to believe.

On the other hand, if you actually replaced 60% of the water twice you would have lowered CYA to 16% of what it was originally, which means it would have been 625 originally, which is very high but quite plausible.

I doubt that this applies, but if the pool water is very murky or cloudy the CYA test can read higher than the CYA level actually is.

Another way to get a very rough estimate of your CYA level is see how much FC you lose over the course of a sunny day. You would need to measure FC early in the morning and again in the early evening of a sunny day and not add any chlorine between the two tests. A CYA level of 50 would lose around 40% to 60% of your starting FC level in one sunny day. A CYA level of 100 should lose less than 10% of your FC level/day.
 
Thanks Jason. When I get home from work this afternoon I will check the FC and see where it's at. I tested it this morning before the sun was up and it was 15 (from all the shocking yesterday and overnight). Your suggestion will help me determine if my CYA results are accurate.

As of this morning when I left for work the pool water was clear for the first time in 2 weeks and I'm hopeful it's still like that when I get home :!:
 
Re: Updated Readings

Here are the readings as of 5:30 pm today:

TA = >400
FC = 10
TC = 10
CC = 0
PH = 7.5
CH = 400
CYA = 80

Pool water is clear and about 78 degrees.

12,500 gallons IG concrete pool with cartridge filter currently running 24/7 (although going back to 8-10 hours/daily)
Pool heater will be turned on (in SW Florida) tomorrow

I'm assuming based on everything I've read that if I can keep the FC levels to 10 with the above CYA then I should be ok.

Why would my TA be so high if PH is 7.5?

How much liquid chlorine (6%) do I need to add daily to maintain this?

Thanks again!
 

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MicheleS said:
After 40 drops I just gave up because it wasn't turning! What is exceptionally carbonated???
Click to expand...

I would define it as TA above 200, but it is an unregulated term (one i made up). :-D

Try retesting and double check the reagent number that you are using. You may accidentally be using the calcium hardness titrant which would lead to no color change.
 
Just re-tested and double-checked all my chemicals and it finally turned light pinkish at about 30 drops :shock: That means my TA is well over 300!!! Double-checked my FC and TC and both are at approx. 7.

If I add 6% liquid chlorine tonight to bring the FC up to about 10 should I add acid and aerate tomorrow? If so, is the pool safe to swim in while I attempt to lower the TA over the next several days? How will heating the pool effect this process?

Thanks!
 
Your TA and CH levels should have been moved to fairly close to the TA and CH levels in your fill water by all the water replacement you have done. A good double check on your test results would be to test your fill water and see what the TA and CH levels in your fill water are. TA and CH levels in fill water being that high is rare but possible. Levels like that are most common in arid regions.

If your TA and CH numbers are right, you are approaching calcium scaling, and calcium scaling was very likely back when the PH was around 8.0. Raising the water temperature will raise the likelihood of calcium scaling further. Be sure you keep the PH at 7.6 or lower if at all possible when the water is heated. As soon as possible, you should work on lowering your TA level, though that might take a while.

With your numbers, it should be safe to swim any time the FC level is around 10 to 15. Risks of calcium scaling can be annoying but they don't make it dangerous to swim.
 
Hi Jason,

Thanks for the reply. What are the signs of calcium scaling? I'm going to search the site as I'm sure this has already been addressed :)

I will try to get the PH to around 7.2 and then aerate to try and reduce the TA as suggested in one of the posts.

Due to the fact that my CYA is still high and the CH is high, am I looking at draining and re-filling (about 30 to 40% of the water this time) again :(
 
Calcium scale forms white or off white to brown patches on the pool surfaces. White scale on white plaster can be difficult to see but will be obvious to the touch as calcium scale is rougher than plaster. Calcium scale on colored pool surfaces is usually quite obvious. Calcium scale on tile can show up as a slight dulling of the tile colors or haze at first.

Be sure to test your fill water before doing any more water replacement.
 
Thanks Jason.

Tested again this morning:

FC = 10/12
TC = 10/12
PH = 7.2
TA <200
CH = 200 to 250
CYA = 80

Not sure what made the CH go down since I haven't added any water. Maybe I just need to get used to testing :? Anyway, based on these numbers should I keep the FC at 10 and just work on getting the TA down by aerating?

I'd really love to start heating the pool again so I can get in it - the water looks great!

Thanks again!
 
Today's numbers are much better. If these numbers are correct you are basically fine, except you still need to lower TA a bit.

TA and CH don't change that rapidly, so you are almost certainly having testing problems. Are you remembering to swirl the mixture, to mix everything, for several seconds after each drop when doing the titrations?
 
I am getting the hang of the testing process since I am doing it twice a day :wink:

Tested the pool again last night and had relatively the same numbers with what seemed like normal chlorine loss for a day in the Florida sun.

FC = 8/10
TC = 8/10
PH = 7.2
TA <200
CH = 200 to 250
CYA = 80

Added liquid chlorine (6%) to get levels back up to 10/12 and checked the pool while it was dark out and light was on and noticed tiny white flakes in the pool that made it look slightly cloudy. I also noticed a small spot near the ladder that looked like it was algae so I brought the pool back up to shock levels (20 based on my CYA and the pool calculator) last night and this morning.

One thing I may have done wrong is I turned the pump off the night before last thinking I could go back to running it 8/10 hours a day. I think I need to continue to run it 24/7 until my water is clear and test results are more stable for several days.

Am I going in the right direction? What will happen if I turn the heater on at this point? The water is about 74 and if I heat it, it will be up to 85.

Thanks!
 

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