Drain and Refill - Advice?

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Ale_Brewer

Ale_Brewer

0
Aug 7, 2015
225
Plano, TX
Okay so I've been reading a lot on here and I have decided to start using the TFP method. I found a good cheap source for sodium hypochlorite and I'm ready to start over. My water has too much CH and CYA so I'm just going to start with a fresh batch of city water, which should put my CH right where it needs to be. I think I have the TFP pretty well down, but it never hurts to have too much information. Any suggestions about what to add, and when, as far as getting my levels where they need to be from the get-go? I'm thinking of going to borates route when it's stabilized. My city water is about 12gpg with a pH of 7.9 and TA of 104. I have the calculator up but I'm mainly wondering if there's a certain order in which I should add things.
 
Any metals in your fill water?

Your first additions will be getting CYA in your water. Start at 40ppm but most Texans typically go up to 50ppm.

Next, adjust the pH down as needed to get to 7.5 or so and then dose your chlorine to the proper target level for your CYA. You can do acid first, wait 30min and then add chlorine. Give it a good brushing in between additions and you should be good.

Finally, you'll want to regularly test your water for the first few days, maybe as much as 2X per day to see what your chlorine demand looks like. Once you get a good feel for the pool's chemical levels and use, you can back off on the testing regimen.

Do you have a TF-100 or a K-2006 test kit?


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Matt beat me to the punch, but he's absolutely right on the CYA. While our temps may slowly try to taper-off in the next few weeks, I would not go any lower that 40. Myself, I've been hovering around 60 all summer to battle the sun, but you can take it slowly and increase later if you need to. Post some numbers for us if you like and we'll compare notes. :)
 
Thanks for the info guys. Here's a link to a "close enough" water analysis of my fill water https://www.ntmwd.com/downloads/WaterQualityAnalysis/2015JulMineralWeb.pdf

No metals really. We get pretty good water around here. So I plugged in my numbers into the calculator and I need some CYA, a little CH, and some acid. No problem. However, it shows my CSI will be 0.41 which is obviously too high. There's so much info on this forum, it's hard to find sometimes. Trying to find the thing about lowering CSI...
 
Unless I'm miss-reading the calculator, .41 should be acceptable right?
Less than -0.6 is suggestive of problems for plaster, tile, stone, and pebble pools. Greater than 0.6 is suggestive of problems for all pools.
Click to expand...

.41 is between -0.6 to .6. Math and Algebra were never my strong suit. :)
 
The biggest driver of CSI is pH and TA. +0.41 is not a good place to start. I would suggest lowering the TA of your fill water with acid/aeration to get the TA to the low end of the range (70ppm) and try to target 7.5-7.6 pH.

If your fill water is close to the recommended level for CH (like say within 50ppm or so), then don't bother adding calcium. It's unnecessary as evaporation and fill will naturally bring it up over time. Adding CH will raise your CSI (make it more positive)


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The reason the CSI is high (and interestingly "their" CSI number of +0.181 doesn't seem to be calculated correctly) is because of the high pH of 8.12. If you lower the pH into the normal range even to 7.7 your CSI will be at zero. It doesn't have to be that close, but you can see that it will be easy to achieve since you want to lower your pH anyway.

The iron is actually not that low since it precipitates readily, but it's probably low enough that it won't result in stains and instead may result in the water getting dull and possibly lightly colored and then you'll filter out the resulting ferric oxide-hydroxide.
 
Texas Splash said:
Unless I'm miss-reading the calculator, .41 should be acceptable right?


.41 is between -0.6 to .6. Math and Algebra were never my strong suit. :)
Click to expand...

It would be fine for pool water but not ok for a spa. If the OP runs his spa with that kind of CSI it would really easy for the water to go over the scaling limit once the temp gets to 104F.


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0.42 is between -0.6 and 0.6 but I'd like to get it lower since I have some scale already. I would like to run on the low side of CSI for a bit. I changed my CH target to match my fill water, changed CYA target to 50, set target pH at 7.5, changed target TA to 90. Under CSI it shows 0.44 on the left and -0.1 on the right, which is perfect. I assume that the CSI number on the left is before adjustments and the one on the right is after.

Oh, and I've never had a problem in the past with staining or clarity with the small amount of iron in my city water. I just read that water analysis and it's not accurate at all for my water. I'm a ways from the plant I suppose. I know where my hardness and pH are at, but the TA will need to be tested. I just ordered a TF-100 but I have a crappy Leslie's kit until that shows up.
 

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Is your plan to wait until the TF100 arrives? (I would)

Also, if you currently have scale on your pool tiles, running a negative CSI will not remove it. It will just keep it from getting worse. You might want to try cleaning the scale off in the water you currently have so that you can dump all that out with the drain before you put good fill water back in.


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I would like to wait until my kit comes in but I really need to do the drain and fill this weekend since I have 3 days off work.

I had a lot of scale when I bought the house. I got the scale off the tile but not the porous stone. I couldn't figure out a good way to remove that. I was hoping that running a negative CSI would remove it over time.
 
You might need a professional for that. I used a bead blasting company a while back that does a modified soda blasting process with kierserite media (magnesium sulfate blasting). It's hard enough to remove calcium scale but soft enough to not damage even glass tile. It works great on stone as well. You can see if it's available in your area. The company in my area is called Arizona Bead Blasting and they are located in Phoenix.


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Ale_Brewer said:
I found a local company that I think does it but their website is pretty basic. How much did that service cost you?
Click to expand...

$3 per linear foot of tile. I had to pay a travel fee as well since his business is in Phoenix. In total, $350.


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Awesome. Thanks for the info. So just an update here. Over the weekend I drained the pool. Well, about half of it. My pump kept losing prime for some reason so I started using a small sump pump that I had laying around but that was taking forever. I have drained the pool before (to sewage) and haven't had any problems until this time. So I filled the pool back up, recharged the DE filter, and tested my water (with my crappy kit) and here's what I have.

15,000 gallons
pH 7.8
TA 80
CH 230
CYA 40
Temp 88

Great! No additional CYA needed. I was planning to run about 50 based on how much sunlight my water sees, but I thought it best to creep up to it. So I follow the calculator and add my acid to get to pH 7.5 and 12.5% liquid chlorine to get to 5ppm as suggested by the CYA/Chlorine chart. This gives me a CSI of -0.1, so all's good. I test for chlorine the next afternoon and I have FC=0 and TC=0. No surprise there, we used the pool a lot the day before. So I add another 77 oz. of NaClO. Wait about 4 hours (with no pool use) and test again. No FC=0 and TC=0.

Am I somehow just burning through chlorine because of the new water? Or should I just trust the pool calculator and blame my test kit for lying to me? Admittedly, the reagents are probably expired. My TF-100 should be here any day now...
 
Can't really advise with known-suspect test results.

Add half a gallon of bleach per day until your TF-100 arrives and don't add or do anything else.


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Got my TF100 in and here's what it says.

FC=0
TC=0
pH=7.9
TA=120 (this may not be 100% accurate because of the new chemical)
CH=200
CYA=30
Temp=88
CSI=0.35

My target CYA is 50 but I only added half the suggested amount of liquid conditioner and I will re-check in a week. I brushed the pool, waited 30 minutes, brushed the pool again, then added the acid. Waited 1 hour, brushed the pool, added chlorine. I suspect there will be 0 FC when I get home today as we got some rain this morning, but I was really surprised that my FC and TC was 0 yesterday after two days of adding 77oz of liquid chlorine. Is it simply because my CYA was at 30? Will post tonight's numbers tomorrow.
 

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