Mustard Algae possibility?? Slamming prior to closing

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fmblizz

0
Jun 5, 2014
60
Marmora, New Jersey
Pool Size
10000
Surface
Fiberglass
Chlorine
Liquid Chlorine
Closing pool in 1 week, pool temp has dropped to lower 70's F.
Water crystal clear.
In past week noticing some blotchy areas greenish/yellow which brush off easily.
Did shock the pool twice in two weeks but appears to not made any difference.
More noticeable in shady areas.

Should pool be slammed prior to closing?? I use a solid cover with bags..

10,000 gallon fiberglass pool

readings today using TF-100

fc = 110
cc = 0
tc = 110
ch = 275
alk = 50
cya = 100 *** test strips show 30-60???
ph = 7.2
 
First, ignore the test strips as they are highly inaccurate. A clear pool does not always mean that the water is sanitary.

Are you sure of your results? Your FC is off the charts too high! If your FC is that high, you PH is likely very, very low. Can you redo the tests and post the results?

The CYA test kit maxes out at 100, so you should to a dilution with tap water so that you can find out your real CYA. Here are extended testing directions: http://www.troublefreepool.com/threads/24188-Extended-Test-Kit-Directions
 
After running all the test again the results were exactly the same with the exception of the PH. Yes the FC is extremely high and yes the CYA is very high but why would this not take care of the Algae problem??

Since the TF-100 does not include a test for PH I use the Taylor K-1000 kit. This time the test showed the PH below 6.8 which is the lowest on the chart so I'm really not sure where it's at .

I can't see lowering the pool a couple of feet to add fresh water just to get a betty CYA reading because as I stated in the prior post it will be closed in a week and since I have well water I am reluctant to add more water due to a possible staining condition in the spring which I fight with continuously

Any thoughts???

Thanks in advance
Gary Blizzard
fmblizz.
 
The TF-100 does have a PH test and it can be found in the blue box. Don't bother testing PH because it is unreliable when your FC is higher than 10. Your FC is way too high to test for PH and no telling what your PH really is. Did you recently add a significant amount of chlorine to the pool because your really did add too much.

Did you do the extended dilution test for your CYA? Without knowing your CYA we can't give you an advice on what your FC should be for closing. Closing a pool with proper levels for: FC, PH, TA, CH and CYA (along with cool water temp) will help ensure that you open your pool to clean water.

Unfortunately your very high FC is keeping you from knowing your PH... it is important for your pool and equipment to have PH in balance.

What staining do you fight with each spring?

FC and CYA need to be in the following ratios to kill algae.

http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

To properly get rid of all forms of algae, you need to SLAM your pool which requires that your PH be set to ideally 7.2 before starting the SLAM:
http://www.troublefreepool.com/content/126-defeating-algae
http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shocking

To get rid of mustard algae (if you have it), you need to SLAM first and then do this:
http://www.troublefreepool.com/content/148-mustard-algae

Recommended levels when not slamming (to help when you finish SLAMing):
http://www.troublefreepool.com/content/134-recommended-levels
 
I stand corrected as it's been a while since a bought the TF-100. I had separated the blue box out as that was basically my weekly test.
As far as adding additional chlorine yes I added 2lbs of granular shock over 7 days to get the algae in check,,, it didn't work...

As far as the CYA diluted test, I split the cya mixing bottle 50% pool and 50% house drinking water. this time the test results showed approx.
55, so I guess doubling it would give a final level in the 110 range.

We have a lot of iron in our area, I use a pre-filter called MetalTrap when adding water to the pool. I also have to add a seqesturant (16oz. once every 2-3 weeks to get the staining to drop off the fiberglass. I'm not really confident that the Metal Trap does very much but I use it. (probably outlived its usefulness after this season).

Since the season is over, should I go through the trouble to get things back in perfect balance as I normally drain 20% of the pool water when closing.

Thanks for you help.
Gary Blizzard
South Jersey
 
Hmmm... 2 pounds of granular shock in 10,000 gallons doesn't explain the astronomical FC level.

Do you mind describing how you did the FAS/DPD test -- i.e. how much water, how much powder you put in, and how many drops of the reagent it took to get rid of the pink color? I find it hard to imagine that you put in and counted 220 drops, which is what is suggested by the number (110) you posted. If there's an extra 0 in the number, that would be more believable...

As a cross check, try the OTO chlorine test (the one that turns shades of yellow) in that separate blue box -- what color do you get?
 
Those results look much more realistic. I suggest that you bring your PH up to 7.2 in order to protect your equipment. Your PH may very well be lower than 6.8 as that is the lower limit of the PH test. Use pool math to determine how much washing soda or borax. Retest PH after you add the washing soda/borax because you might need to add more if your PH is much lower than 6.8.

Pool Math:
http://www.troublefreepool.com/calc.html

Your FC is too low for your CYA to be useful in keeping algae away, see the Chlorine CYA Chart:
http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

Since your CYA is over 100, per pool math, your FC shock level is 43. You should only use liquid chlorine at this point as granular and solid forms of chlorine add CYA to your already too high CYA.

You should consider replacing some water to get your CYA levels down so that your FC shock level is more manageable. You don't have to bring it down to 30, but a CYA of 50 or 60 would be much more manageable than 110. Also, the high FC levels needed for your CYA will also make the metal staining worse, so a lower level CYA will allow you to have a lower FC which will help lessen the likelyhood of iron staining. http://www.troublefreepool.com/content/137-metals-in-the-water-and-metal-stains
 
Is it possible to put too much chlorine in when Slamming??

I drained approx. 3500 gallons and refilled to bring the CYA into a manageable position. My CYA is still between 60 & 70 but given that, the shock number I'm shooting for should be in the area of 26 I believe according to the Chlorine/CYA Chart.

I filled the chlorine test vial to the 10 ML point and added a scoop of DPD powder just to see if I had any residual chlorine. As expected the solution did not turn pink.. I then add 6 gallons of Clorox 8.75 and retested. When I added the DPD powder it turned pink but then turn clear almost immediately as I swirled the mixture. According to the instruction that come with the TF-100 (If it does not turn pink, you have no Chlorine) so I added another bottle of Clorox and retested.. I kept adding bleach for a total of 12 gallons and always had the same result (it turned pink initially but clear after I swirled the solution).

12 gallon's of 8.75% chlorine in a 10,000 gallon pool???

Just out of curiosity I added a couple drops of R-0871 and low and behold the mixture turned bright red. I started counting the drops and it seemed to get more red. I put in a total of 60 drops and the DPD solution never gave any indication of getting lighter so I stop because I didn't want to run out of the R-0871.

Did I do something wrong which also brings me back to my initial question (can you over chlorinate when slamming)???
 
Why did you add 6 gallons of 8.75% bleach? According to PoolMath, that should increase your chlorine levels by about 55 ppm (about twice what you were aiming for). Adding a total of 12 gallons would be about 110 ppm -- oddly, just about the levels you first reported in this thread :eek:

I don't know what the reagents do when the levels are that high... However, if they still behave in the normal way, you would have had to add much more than 60 drops to make the color disappear (60 drops would indicate FC at 30 ppm, and you were already well above that after the first 6 gallons).

I don't know of anything you can do to reduce the chlorine levels more quickly than just letting the sunlight break it down for you. Make sure the pool gets all the sunlight it can (no covers). I sure wouldn't go into the water at those chlorine levels.

As for the future, use PoolMath (http://www.troublefreepool.com/calc.html) to tell you an appropriate amount of bleach to add. As for the test, if the first scoop of powder doesn't make it stay pink, add a second scoop (before doing the drops). I don't know what the TF100 instructions say about this, but the K-2006 I use (same chemicals) has instructions to add DPD powder until you get the pink. Of course, you do have to use common sense -- if there's no chlorine in the water, no amount of powder will make the sample turn pink, so you wouldn't keep dumping more powder in if you suspect you have no chlorine.

Also, after adding chlorine, let the pool circulate for 30 minutes before retesting, so that the new chemicals have time to mix in.

Always use common sense -- if you know you just poured X number of gallons of Clorox into the pool, don't believe a test result that seems to tell you there's zero chlorine in the water half an hour later -- you know you just put some in...
 
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Thanks all for the helpful replies.
Just a little update. Since I overdosed the pool with chlorine, I drained about 1500 gallons and refilled again. My CYA reading is now at 50 and my FC is at 60 so big difference. I'm giving it a couple more days of full sunshine to cook off some more Chlorine.. I think I will just ride it out from this point and close the thing up on Sunday. I don't have a heater so the only metal in my system would be a concern is the pump motor and a couple stainless clamps.

On a good note, I haven't had any signs of algae that for sure... LOL I guess what I did was a Grand Slam, though not intentional .


Gary
 
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