TF100 Results, input sought

[rigersa]

First post, lurked a bit last summer... Trying to give a lot of context here so forgive the length and any extraneous info. Wondering what others would do to regulate this pool now and in the future. I know it is low on chlorine. Figure best to wait for input before correcting that.

• 2nd summer with this water, pool opened March 2014.
• dichlor shock this summer, probably 15 pounds total used since 3/14
• hyperchlorite shock last summer, probably 20 pounds total used since 3/14
• trichlor tablets both summers, probably 60 pounds total used since 3/14

Ordered and used the TF100 for these results below. Found it easy to use but I have trouble believing my calcium is QUITE that high. Should I be waiting for ANY color change to purple to end the test? Also, the black dot test for CYA felt like a dream sequence or something. Did I really see it?

FC	.5
CC	0
TC	.5
CH	700-800
TA	90
CYA	100+ (~110?)
Basic cl reading	.5
Basic ph reading	7.2 or 7.3

Thanks everyone!

 

[Divin Dave]

Hi,
Welcome to TFP.

well, your CYA is way too high.
With CYA that high and your FC that low, Im surprised you dont have any CC's.

the thing to do with CYA that high, is to replace about half of the water, that would also bring your CH back into more manageable range.
- i understand the hesitation of folks to drain water in a drought - Reverse Osmosis of the pool water would be the alternative.

I would however add bleach to a FC level of 15 so algae dont take hold until you have gotten the CYA down.

AFter the water is replaced, run a full set of test results again and start from there.

 

[tim5055]

Welcome to TFP!

First, never wait on chlorine. As long as it is low you chance growing something in the water. I'd bring it up to 15.

Out west, I can easily believe the high CH. test your fill water and see what you are putting in the pool to top off.

You can't extrapolate a little over 100 to 110, or any number. The test doesn't work like that. Your two choices to get the CYA down to a manageable level partial drain/refill or reverse osmosis if it is available in Vegas.

From this point forward no solid forms of chlorine, liquid only.

How does the pool look?

 

[duraleigh]

Welcome to the forum. Nice to see quite a few lurkers joining the crowd.....we're glad you are here.

The Southwest has a history of high CH coupled with your use last year of Cal-hypo indicates your CH really is that high.

1. I would suggest a partial drain of the pool to reduce both CYA and CH. Your CYA is almost unmanageable and your CH is not much better

2, Mix a solution of half pool water and half tap water. Use that solution to perform the CYA test once more. multiply your results by 2 to get a rough approximation of your true CYA. Post that result and we'll suggest how much to drain and refill.

3. Test the CH of your refill water and post that as well.

 

[Donldson]

First, welcome from someone who lurked a lot before posting as well!

Your CYA and CH are both quite high, both of which can only be reliably lowered by changing water or reverse osmosis. Your use of dichlor, trichlor and calcium hypochlorite would be what caused all of that. Dichlor in particular raises CYA almost as much as it raises chlorine levels. Switching to liquid chlorine would control those levels going forward and is something you should certainly consider.

 

[rigersa]

How does the pool look?

Great. Clear. Always. Probably part of my problem that it is just now getting my attention.

the thing to do with CYA that high, is to replace about half of the water

I have been told that draining/replacing water during 100 degree weather and full sun is not a good idea and to wait. But that would mean a couple months though here. Don't mind doing if it is recommended though, of course. Would need to then look into what to purchase/rent/etc to do the job.

Mix a solution of half pool water and half tap water. Use that solution to perform the CYA test once more. multiply your results by 2 to get a rough approximation of your true CYA. Post that result and we'll suggest how much to drain and refill.

60 x 2 = 120

3. Test the CH of your refill water and post that as well.

425 for the water from the hose to get it a decided, crisp blue. 300 before it starts to change visibly to purple. (Which reading is correct?)

 

[Divin Dave]

If you're worried about your plaster while draining and refilling, you could put a water sprinkler on it.
draining and refilling 8,000 gallons of water really doesnt take so long as to worry about it I dont think.

best way to drain is using a sump pump. They rent for about 35/ day or you could buy a cheapie from Harbor Freight.
a decent sump pump will pump 8K gallons fairly quickly.

GPH from a water hose or 2, could be easily calculated to figure out long it will take to fill back up.

 

[tim5055]

Everyone agrees that a partial drain and refill is the best option, but not the only option. You can maintain the pool with high CYA and high CH. you just have to be diligent in keeping both your FC and pH where they need to be all the time.

FC needs to stay above 9 and you should probably target 13 to stay above 9.

Keep the pH between 7.2 - 7.4

Decide how you are going to treat the pool moving forward. All solid chlorine has to be out. Liquid chlorine or add a SWCG. If you were going the add a SWCG then your CYA is only 40-50ppm too high.

I started at 200+ CYA and took about 18 months to get it down to 50.

 

[duraleigh]

425 for the water from the hose to get it a decided, crisp blue. 300 before it starts to change visibly to purple. (Which reading is correct?)

425. Any color change test is completed when the LAST drop you added made no further difference.

 

[rigersa]

Thanks everyone. Used the poolmath page and added requisite liquid chlorine. Will do a water change when I can!

 

[Earl Cox]

Welcome lots of help here just follow you will be good to go in no time

 

[rigersa]

Updated after a 20-25% water change. Figured I would update everyone as to what a water change did. Thanks again everyone. One more change to go.

FC	5.5
CC	0
TC	5.5
CH	700
TA	110
CYA	80
Basic cl reading	5
Basic ph reading	7.5

Oh, and the water change itself: I drained about 4,000 gallons over 5 hours (7 to midnight) with a 1/3 HP sump pump pushing water through 120' of 1.25" hose and refilled the 4,000 gallons with a single garden hose over about 8 hours. Was able to avoid the sun hitting plaster.

 

[pooldv]

Chlorine is low for your CYA, need to keep it at target, Chlorine CYA Chart

TA is high and could cause your PH to rise, keep an eye on PH and keep it under 7.8 using muriatic acid. This will slowly lower you TA, Pool School - Lower Total Alkalinity

CH is high, it is important to keep your pool CSI in the target range. Managing PH is the easiest way to tweak CSI. Put all your number into Poolmath and it will tell you current CSI then you can tweak the numbers to see what keeps it in range. More here, Pool School - Calcium Scaling

Pool School - PoolMath