I am a newbie, check my math please

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larryca

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Jul 11, 2012
26
Modesto, CA
Hello, I have found this site to be a wonderful place to get some true answers. I have been mainting my pool myself since my builder went out of business last year. I have been lucky I guess, until now. The last few months I had seen a rise in TA with a simple test strip. My SWG panel keeps shutting the cell off due to low salt @ 2200ppm. My FC has fallen to 0.5-1.0 quite often. I get occasional green algea spots in the shady areas of my pool. I bump the SWG to get it to turn on and I brush. The algea easily brushes off and I assume it's gone. I started having Leslie's check my water and they said everything is perfect and all I need is about 20 cases of Phos-free. Well maybe not that much but, you know what I am saying. The phos-free seems to help for awhile but then the algea got worse. I found you guys and ordered my TF-100 kit and I see my numbers are bad. My salt cell was telling me 2200 but, the aqua-chek strip read 2700. I bought 80 lbs of solar salt and the panel reads 2900 and it is staying on. I haven't re-tested with the strip yet. Assuming it is at 3400, my target. I thought I would be ready to start shock process but, looks like I need to do a large drain and re-fill. Wish I would have waited on the salt. The pool calc says drain 41% for high CH and 17% for high CYA. Just so I don't go back and forth getting the water balanced before I shock it, and seeing how you guys predict the effects of the changes that need to be made, can someone give me the steps I should take before I get to the shock routine. I plan on using bleach. I want to add borates, but still a little confused about it. Thanks.

salt 3400 (I think)
FC-3
CC-0.5
PH-8.2
TA-190
CH-510 (Tested twice to be sure)
CYA-110 (A little below the 100 line, so I approximated)

I have been getting a real bad white line on tile and rocks. Cleaned tile with pumice and it comes right back. New stain looks like a fatter grey film than a thin white scale. Been brushing rocks with no success. It is getting a lot worse since adding Phos-free. Not sure if that is why but, I assume the high CH is the problem.
 
Welcome to tfp, larryca :wave:

Were glad you found us!

It is likely your cya is higher then 110 since the test is not accurate up there. Do a dilution where you do half pool water and half tap water, then use that to fill up to the label, then the reagent to the top. Multiply your results by 2. This should give you a better idea of how much drain and refill you need to do.

The high CH can be lived with. Have you tested your refill water? With high CH, you will need to lower your TA and keep your ph around 7.2-7.4 to prevent the calcium scaling you are seeing. You can deal with those after you drain/refill.
 
Thanks for the reply.

I performed the diluted CYA test and got a result of 100.

I tested my fill water and it has a CH of 120. That is what I get on my 4 way strip I use in my spa when I refill it also. So I believe that. The PH of the fill water is 7.3. Again that is what I usually see in my spa after refill.

So should I drain 40% of my pool before I start? My builder told me to drain my pool about 3 feet each year or half way every other year. I think he was referring to phospahtes but, I am not positive.

Will brushing the rock and tile after the water is balanced remove that scale or will I have to use acid or some other cleaner to get rid of it?

Thanks again
 
It sounds like your CYA is closer to 200 which makes algae very hard to control. Draining 50% of the water is a good place to start.

Your pool builder's advice to periodically drain the pool is - for lack of a better word - "old school" pool advice. The common notion is that TDS builds up over time and this makes chlorine less effective - therefore the need to drain. While this is not precisely true - most pool services companies use CYA containing products and so there is a build up over time.

If you maintain your pool based on the recommendations found here there is no need for periodic water replacement.

As to your scale - if you get your PH down to 7, some scale at the water line may dissolve away. Don't expect any heavy scale or anything not in direct contact with the water to fix itself. Also your TA looks pretty high - especially for a pool with high CH and a salt water generator. The combination of high TA, high CH and high PH cause all that scale.
 
larryca said:
Okay. That's what I thought. Thanks for confirming. I'll get that done ASAP and post the numbers. Is there any amount of wait time after refilling before re-testing the water?
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A couple hours ought to do it, I'd think. With the pump running, of course. And some brushing here and there to really get some cross-currents in the dead spots. A Wall-whale brush is ideal for this. One good shove across the bottom and in a few seconds you see a water spout on the opposite wall.
 
OK. I drained a little more than half of my water and re-filled it. my numbers are now:

Salt - 1600 (that is on the display but, prob 2200-2300)
FC - 2
CC - 0
TA - 170
CH - 290
CYA - 40
PH - 8.0

I was going to shock and worry about the salt and the rest later but, I think I read that the PH needs to balanced on the low side first. Since I killed the CYA down should I use some tabs instaed of just bleach to shock? Anything else I should do before I shock?
 
larryca said:
OK. I drained a little more than half of my water and re-filled it. my numbers are now:

Salt - 1600 (that is on the display but, prob 2200-2300)
FC - 2
CC - 0
TA - 170
CH - 290
CYA - 40
PH - 8.0

I was going to shock and worry about the salt and the rest later but, I think I read that the PH needs to balanced on the low side first. Since I killed the CYA down should I use some tabs instaed of just bleach to shock? Anything else I should do before I shock?
Click to expand...
Leave that CYA where it is!! Adjust your pH to 7.2 then ignore it until you're done with the shock process. In fact, ignore everything except FC & CC until then.
 

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It is not really possible to "shock" with pucks, they do not dissolved quickly enough to raise the FC.

Do as Richard has suggested ... pH then bleach until you pass the 3 tests to stop the shock process.

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone ;)
 
I shocked all day yesterday. I only had to add more bleach after the first hour. It held steady all day. I brushed good after hour three and water got cloudy. It cleared by early evening. I tested after sunset and again this morning just before the sun hit the water and I only lost 1 part FC. I have been reading 0 CC since hour three. The water looks clear and all the green stains are gone. I didn't have a large algea problem. It was just reoccurring constantly. So am I good to go or should I shock it all day and test again tonight?
 
Oops, I was just reading another post and read that he needed to shock the cover, toys, the vacuum, etc.. I just realized that I have had the waterfall and the solar off this whole time. I switched both on and I'll continue to shock today and see what happens.
 
Sound like a good plan to get the water through all the plumbing. Keep it up and sounds like you will be done quickly.

So there are no visible signs of algae at this point?

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone ;)
 
No signs of algae. I added a small amount of chlorine this morning to bring back up to proper shock level and FC has held for three hours and still no CC. I brushed very well for over an hour again and the water got a little cloudy. It seems to be clearing up already though. Have been running solar and waterfall all morning. I'll start checking every 4 hours today to ensure shock level and then perform ONCL test. I have to work tomorrow so if I pass all three tests in the morning can pool just sit all
day until I can start balancing other numbers. I'll post them in the morning and see what is recommended. Should I let FC level return close to normal before I plug SWG back in. Otherwise it will take a long time to fall.
 
Water looks beautiful this morning. Better than it has in a long time. I lost 1.5 parts of FC overnight but we had an overnight thunder storm and I guess we got quite a bit of rain. Not sure exactly how much. But my FC was holding good all day yesterday, so I think I should be okay. My readings this morning were:

Salt 2040
FC 13
CC 0
TA 140
CH 300
CYA 40
PH ? Forgot to test it.

I can put all this in the calculator and see how much to add but, I'm not sure what order to do things in. I do want to add borates. Where do I begin.
 
the only thing I see you may need to adjust is the salt. Also note the pH test is actually inaccurate when the FC is greater than 10ppm.

You may want to hold at shock level one more night to confirm the OCLT.

Posted from my Droid with Tapatalk ... sorry if my response is short ;)
 
I agree with jbliz, I would do another OCLT, though rain is likely your culprit.

When you get to borates, make sure you drop you TA first down to 70-80 ppm, since it will be more difficult to lower after adding the borates.
 

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