Making Steps Toward TFP - Requesting Input

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Hey tim5055 - Yes, I was asking them about deicer (specifically Tetra Flake since that's what I found online that HD carries and pool school mentioned by name). The price was $10 for a 50 lb bag. Glad you included that you used to live in Severna Park; I was wondering when I was reading your post how you knew Defense Hwy.

Thanks for checking Defense Hwy store; that was really nice of you. Their price is higher. $11/5 lb x 5 = $55 vs Leslie's 25 lbs for $47.

Big price difference between "decier" and "pool hardness increaser" but I'll take some solace in getting it cheaper at Leslies rather than think about how much more I spent because it's got some fancy pool stuff name. haha

I'm going to start adding some to the pool so I'd still welcome anyone's input on target, calculations and adding.
 
We bought a 25# bucket of calcium chloride at Leslie's and have added it incrementally over the last 2 days. After incrementally adding 13# tested CH and it was right on target with a reading of CH:200. Added the remaining 12# incrementally and finished up with the expected CH of 250. Didn't run in to any issues with clouding from the addition of calcium chloride.

Here are our latest test results from 6pm yesterday:
FC: 7
CC: 0
pH: 7.2+
CH: 250
TA: 70
CYA: 60

As stated earlier the pH was dropped to 7.2 four days ago in anticipation of SLAM that didn't need to be done. Prior to yesterday the pH was clearly at 7.2. Yesterday it looked a little darker but not enough to match 7.5 reading. The pump has been run a lot more than usual the last two days during the addition of the calcium chloride.

The CH at 250 is at the low end of the recommendations from pool school. The pool will be closed for the season with a mesh cover that allows rain/snow into the pool water. In prior years the pool would have been closed by now. Don't know when to expect pool temp to drop below 60 degrees so don't really know when it will be closed.

Should the CH be brought up higher in anticipation of this dilution?

Any other recommendations at this point other than daily bleach additions based on pool calculator and regular testing?
 
Sorry, I missed this one - but you missed the neat bump smiley:bump:

Yes, I would probably bring above the minimum recommendation before you close. How much:confused:

Where do you think you want to keep it next year after you open? If you wanted lets say 300 just bring it up to there now.

Everything if looking good. Just keep testing and adjusting.:goodjob:
 
You can if you like and it would help, but letting your pH try to live at 7.8 is going to have more of an effect. Plug in all your numbers to Pool Math and play with the levels of CH versus pH. See what that does to your CSI number which tells you whether your water is corrosive, neutral or scaling potential.
 
Smykowski said:
No need.
Click to expand...

I would like to make one correction for the OP - OCLT's are only valid at shock FC levels. An OCLT performed below shock level is inconclusive. I have posted many times about this to other TFPC newbies.

- - - Updated - - -

With that said, it looks like your water was at very high FC levels for quite some time so I suspect your water is fine. Just keep in mind that the End Of SLAM criteria were developed and intended to be check at shock FC levels, not normal Target FC levels.
 
Yes I missed that cool bump smiley, dang it; but now I know so watch out.

I don't know the best level to keep CH next year after opening. I only have the recommended levels of 250 - 350 to go by. I was just thinking about what the CYA may be after the winter dilution and that led me to thinking that the CH would be diluted also. I didn't know if I should be concerned that the pool may sit over the winter with the CH dropping along with rain/snow.

I just now used the pool calculator in reverse - plugged in 300 as now and 250 as target. It told me that would require a 22% water replacement. In a normal winter that's probably a reasonable estimation of the water turnover. I'd say last year it was more since I had to pump out water twice over the winter.

I don't want to overshoot and go through another drain/fill. If I bring it up to 300 now then a 22% water turnover would drop it to 250 and if there's a lot of precip that may take the water turnover up to 33% which would drop CH to 225. So 300 is probably a good number to achieve in prep for winter. Agree?
 
JVTrain: Thanks for that input. Now that I feel I am getting over the initial learning hurdle I have started to play with CSI using pool calculator. It is good to know the pH influence on that. My pH has been rising and is currently at 7.5. I have noticed a big difference in CSI just changing the water temps. I'll play around with it some more.

SunnyOptimism: I have seen your posts recently about OCLT needing SLAM FC levels. Obviously I did not know that when doing the OCLT mentioned previously. In fact, after seeing you mention it on another post I went back and re-read the OCLT directions. Those directions do not mention the need for SLAM FC levels or the need to run pump during OCLT. The directions say the OCLT "can also be useful if you are unsure if there is a problem or not". If someone is doing the OCLT for this purpose they would not be at SLAM levels or have pump running 24/7. Thanks for spreading the word about this.
 

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swoopman said:
JVTrain: Thanks for that input. Now that I feel I am getting over the initial learning hurdle I have started to play with CSI using pool calculator. It is good to know the pH influence on that. My pH has been rising and is currently at 7.5. I have noticed a big difference in CSI just changing the water temps. I'll play around with it some more.

SunnyOptimism: I have seen your posts recently about OCLT needing SLAM FC levels. Obviously I did not know that when doing the OCLT mentioned previously. In fact, after seeing you mention it on another post I went back and re-read the OCLT directions. Those directions do not mention the need for SLAM FC levels or the need to run pump during OCLT. The directions say the OCLT "can also be useful if you are unsure if there is a problem or not". If someone is doing the OCLT for this purpose they would not be at SLAM levels or have pump running 24/7. Thanks for spreading the word about this.
Click to expand...

The OCLT and other two criteria ASSUMES you are at the end of the SLAM process and therefore already at shock levels of FC. And I do believe the SLAM article teaches that the pumps need to be running all the time. One other point lost in all of that is, if you have an SWG, it should be turned OFF during a SLAM and OCLT.

But yes, the SLAM and OCLT articles should be re-written to better clarify that point as too many people think they can use a Target FC level OCLT as a diagnostic tool when it is not.

I have no ability to EDIT any of those articles so it would have to be up to the TFP Site Admins to correct that information and provide a more in-depth, technical discussion of the SLAM and OCLT processes.



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SunnyOptimism: Yes, I agree, the OCLT directions ASSUME you are at end of SLAM. I think that phrase I quoted leads to the newbie confusion in thinking it can be used as a diagnostic tool without following SLAM protocol. That is how I interpreted the directions. That's also why I said thanks to you for spreading the word.
 
It has been discussed that if your doing an OCLT to verify organics or not, and not involved in an on going SLAM, you can use an elevated FC level for the OCLT. Example being if your shock level is 16 for a CYA level of 40, you could raise your FC level up to 10-12 ppm or any FC level above 10 and do the OCLT. This also makes it that you have to use the FAS/DPD test for accuracy, doing a OCLT. If you lose more than 1ppm you have something consuming chlorine.
One the other hand if you are in involved in an ongoing SLAM and your looking to pass the OCLT then it is recommended to do the OCLT at shock levels. ?
 
SunnyOptimism said:
I would like to make one correction for the OP - OCLT's are only valid at shock FC levels. An OCLT performed below shock level is inconclusive. I have posted many times about this to other TFPC newbies.
Click to expand...

This is somewhat of an "old wives tale" on the forum in my mind. The OCLT end result should be zero if the tests were preformed 100% correct regardless of the starting FC point. The 1ppm loss was built in as seldom is the test preformed 100% accurately. The largest idea to keep in mind is WHY a member is preforming the OCLT. If a member is preforming the test to see if they have completed the SLAM process, then yes, shock levels should be maintained. If they are simply preforming an OCLT to see if they have any issues, then there is simply no need to raise the FC level to shock level.
 
From the technical discussions I read on this matter, the main issue is that chlorine loss rate (ppm/hr) is not constant but a function of chlorine concentration.

OCLT = LR([FC]) x time

Where LR is "loss rate". Loss rate is a complicated function of FC level, organic load, biological contamination, etc.

Since the loss rate of chlorine is higher at higher chlorine concentration, you use the OCLT at shock levels and at night because it ensures that your loss due to biologicals and sunlight is at a minimum (assuming your SLAM has killed everything) and you're only looking at a loss due to organic load and the inherent chemical degradation of FC itself.

Doing an OCLT at target FC means potentially testing where the loss rate could be too slow to be meaningful in an overnight period (8 hours or so).

A crude analogy would be that doing the OCLT at shock level is like looking at something under a microscope or bright light. You have a better chance of finding a problem when you magnify the FC concentration.

I did not develop the OCLT and so what I have written comes from my searches of the TFP threads. If the person or persons who developed this procedure could post up technical documentation, then that would eliminate the problem with "old wive's tales".


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Thanks pwrstrk, Leebo and SunnyOptimism for the interesting and informative discussion on OCLT.

These are my latest test results:
FC: 9
CC: 0
pH: 7.8
CH: 300
TA: 80
CYA: 60

I plugged in the following numbers (% in parenthesis is guesstimate on dilution from rain/snow - have a mesh cover) and ran csi for temps of 60, 50, and 40 degrees.
CH: 225 (25%) | 240 (20%)
CYA: 45 (25%) | 48 (20%)

Within these parameters the water stays balanced. However I have read that the pH tends to drift upwards over the winter. So I plugged in different pH numbers. Up to pH 8.3 the water stays balanced. Changing to 8.4 indicates potential for scaling.

At my current numbers dropping the pH to 7.5 would still be balanced. If the water temp drops 10 degrees without the pH rising then the csi shows potential for corrosion.

My question is this: do you think the pH should be dropped to 7.5 before closing to reduce the potential of scaling if the pH will rise over the winter?

Thanks!
 
Sounds like you ran a lot of scenarios for CSI. As you can see, it looks like you have a lot of margin to keep your pool in balance. I see no problem with lowering your pH to 7.5 except that it's not going to stay there long. But you won't hurt anything doing that.

During the winter, can you check you pool water? Or is the pool totally closed up at that point?

Another thing to keep in mind is that the CSI is just an index. Like so many indices, it's not determinative, that is, it's a suggestive value. It tells you that you can possibly have etching or scaling, not that you will definitely etch or scale. That is why the range of "Balanced" values goes from -0.25 to +0.25. If you can keep it at 0 or slightly negative, then you'll be ok. Even a slight positive number is not something to lose sleep over.


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Thanks SunnyOptimism. Yes, I ran a lot of scenarios. It was a good learning experience. Thanks for the comment about CSI being an index. I did wonder at one point if I was over-analyzing but since I was learning so much and gaining insight into how the different aspects affect one another I kept playing with it.

Plugging in a pH rise is what kept moving the CSI into positive numbers. I read on the forum that pH rises in the winter and thus my reason for asking.

I think I will go ahead and lower the pH to 7.5.

During the winter the pool has a mesh cover with spring straps on anchor holds in the concrete deck. A few straps can be removed to gain access to a part of the pool. If the pool needs draining from large amounts of rain/snow we remove a few straps and drop in a submersible pump to drain out excess water. It's not fun but it can be done. Last winter it had to be done twice to remove water. Despite draining lower than normal when closing plus draining twice, the pool was still full when opened.
 
Ok. So if you got into a situation where you really felt you needed to lower the pH, then you could add some acid to the pool and drop in the submersible pump without the drain hose attached and let it circulate the water for you. Or you could drop the pump in the deep end and put the drain hose in the shallow end to get better circulation.

Actually the proper sequence would be to get the submersible running first and then add any acid SLOWLY and in small quantities.


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Yes, SunnyOptimism we could do that, thanks. In fact we put the submersible in the deep end with the hose running into the shallow end during our drain and fill to keep some circulation going. Of course, there was no cover in the way then. :)

Do you think checking it once a month is sufficient (keeping in mind that we have to remove some cover to get a water sample)?
 

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