Pool Refill Procedure

[Hanstb]

Hello TFP,

I’m in the planning stages of refilling our pool, the pool was emptied to facilitate major maintenance and the remodel of the back yard area, the pool is not new, is fully cured, and was not modified.

The pool is described in my signature line, but please let me know if I left out anything relevant.

After some testing, I can blend my well water with treated water to produce a ‘Fill Water’ with the following characteristics, the blending affected the CH and pH (very slightly) but little else:

FC/CC - 0.0
pH – 7.5
TA – 360 (Very high, I know, tested numerous times, this is accurate)
CH – 260 (Blended down from 460 at the well)
CYA – 0.0
Salt – 150

Given the values above, what would be the recommended procedure to fill the pool and attain the ideal water balance in the most efficient manner?

I assume I need to tackle the TA right away by adding muriatic acid to lower the pH to 7.0 and aerate the pool to return the pH to normal levels as the TA drops to the desired level (60)?

I also assume I need to slam the pool, should that be done before raising the CYA to the 70 to 80 range prescribed for SWCG pools in an effort to conserve chlorine?

Perhaps raising the CYA to 30 initially until the SLAM/OCLT procedure is complete, and then raising the CYA to 70/80 and adjusting the FC to 5/6?

Is adding the salt at the onset a non-issue although the cell will be bypassed, or is there an ideal time to add the salt?

The target water balance is the TFP suggested chemistry for SWCG pools, I am on the fence about Borate, but I'll tackle that once the water is balanced and ready to go.

I would like to get this right the first time without wasting time and materials, I would greatly appreciate any advice.

 

[jblizzle]

There is no requirement to actively adjust the TA. It will lower as you add acid to maintain the pH.

The procedure is:
Fill the pool.
Circulate the pool.
Test the water.

You will want to get CYA dissolving and FC into the water first. There should not be a need to SLAM the pool.
You can add salt whenever you like. Circulate for a day before turning on the SWG.

 

[Dirk]

If you have the means to get any sort of flow meter on the hose that'll fill your pool, this is a great opportunity (which doesn't happen often) to confirm the volume of water in your pool. The more you spend on the meter, the better number you'll get. They have inexpensive ones at the big box stores. The one I used goes for about $60 online, but I was able to repurpose that elsewhere, so it wasn't a one-time expense for me.

City-folk that fill their pools "from the street" get to use their home's water meter for such a trick.

 

[Hanstb]

Ok, so just fill and target the final water balance using the recommended values?

The custom with local pool companies is to shock the pool with trichlor to raise CYA and sanitize the pool, that's what lead me to believe a SLAM was required.

I will be using Cyanuric acid and 12.5% Sodium Hypochlorite to set my initial CYA and FC, so I will take your advice and simply fill, circulate, test, and adjust the levels accordingly. That is whole lot easier than what I had in mind!

As for the TA, should I target a lower pH value initially to promote a speedy reduction in TA, or just shoot for 7.5 and let it ride?

The flow meter is a terrific idea, thank you!

 

[jblizzle]

Depends on how quickly you want to lower the TA.
If you want to actively lower it, follow the Lower Total Alkalinity procedure.
Otherwise, just maintain the pH.

Note: Trichlor is slow to dissolve, so it should never really be used to "shock" a pool. Dichlor will dissolve more readily, and will also add more CYA.

 

[Hanstb]

I misspoke, Dichlor is used locally to shock the pool and raise CYA not Trichlor, my mistake.

Is there any benefit to lowering the alkalinity quickly using that procedure? I am certainly willing to do it if it's advantageous.

Thanks!

 

[jblizzle]

No real benefit either way. You are either actively working on the TA by adding acid and aerating, testing and adjusting maybe multiple times a day. Or just letting the pH climb on its own and adding acid every few days.

 

[Hanstb]

I have an Intellichem controller with acid pump, would you suggest I just set it and let it do its thing? I test manually to confirm the pH, but let the Intellichem do the dosing, it's been reliable to within .2.

 

[Hanstb]

Hello again everyone,

The pool is filled anew and now the fun begins, here are the test results after 72 hours.

FC - 5
CC - 0
pH - 7.3
TA - 240
CH - 200
CYA - 70 (Calculated by Pool Math based on Dry Stabilizer addition, test results are between 40 & 50)
Salt - 3800
CSI - .55 (Based on CYA of 45)
Temp - 81F

I undershot the CH by a bitt but my first thought is to leave it be since it will climb on its own from makeup water, but if that's not a good plan, I'm all ears.

There is enough dry stabilizer in skimmer socks to bring the CYA to 70 once the chemical is fully disolved.

Barring something I haven't thought of, only my TA seems to be an issue, how should I best go about managing pH until I get TA in check? Will maintaining a pH of 7.2 / 7.3 be sufficient to bring the TA down to acceptable levels, what should my target TA/pH be? (Jason suggested that actively lowering the TA was not necessary, and I would just as soon avoid the acid/aeration technique if I can.)

I filled the pool through a quality water meter, I also calibrated the meter before start, and verified it during (at the 50% point), and after the fill, the pool took exactly 22,717 gallons to fill from bone dry to when the first drop crested the overflow, a full 7,000 gallons less than the PB informed during design and construction, if I had to guess, the difference comes from the swim outs, steps, benches, hight above the waterline and some fuzzy math to account fo the very irregular shape, but the fact is we're dealing with a 22k gal pool.

Thanks!

 

[mknauss]

Follow what Jason posted. Maintain a reasonable pH based on your CSI (right now the 7.3 you show is good, when your TA falls, a higher pH is warranted). Once your TA is around 70 or 80 ppm your pH should stabilize. However you most likely have high TA fill water (have you confirmed that?) and thus if you use fill water you will be continually using acid to lower pH that is driven up by the TA.

 

[Hanstb]

Marty,

Yes, fill water TA is high, 360!

I did a day of acid/aeration to get the TA to 240, it was time consuming and ate up a huge amount to MA. I don't want to keep doing that, it's a pain and expensive. I just wanted to make certain I could go the slow and steady way from here on out and confirm the pH targets.

I am strongly considering Borate in the future, but I want to get everything stabilized and under control first.

Thanks!

 

[mknauss]

The acid amount used will be the same either way. That is based on chemistry. One way you do it in a day or two, the other takes frequent testing and adjustment over a month or so. Remember, you must test your TA (and should be checking your pH even with the probe) to see were you are in the process.

 

[Hanstb]

That makes sense, but little by little is easier to manage so long as the high TA does not cause a problem in the interim. I have already poured 9 gallons of MA into the pool over a thee day period, I would prefer to let the dosing pump take it from here. I am basing everything of TF-100 test results, the probes are new and while the pH probe has been spot one so far, I am only recording probe readings for comparison, and only referencing pool math plus test results for water balance.

I have been testing every few hours for the past three days, but starting today I am transitioning to a twice daily schedule, once at sun up, and once at sun down, that way I can keep to a rhythm and have good comparative data.

The challenge will come when I am away from home for a few days, that's what all the fancy automation was supposed to solve, but didn't!

 

[Dirk]

I'm hearing some most excellent work going on here. Nice.

 

[Hanstb]

Dirk,

Thank you for all the advice, in this as well as other threads, as I prepared to refill the pool. Your suggestion to use a water meter to fill the pool was especially helpful, I was taken aback by how far off the builder's estimate was!

Here is a (poor) picture of the contraption I assembled from your recommendation, the orange valve was for hard water, and the blue for soft water, I undershot the CH but my calculations where based on 31,000 gallons, the pool volume is actually only 22,700, so the hard water top off was insufficient.

The black tape towards the outlet elbow was there to keep the CYA filled sock from sliding off the pipe, I simply tie-wrapped it on and let the fill water dissolve it, very effective, about 75% of the required Cyanuric acid was added during the fill process, the remainder in socks placed in each of the two skimmers. I also added MA and Bleach in stages during the fill, using partial fill volume and pool math, the Maytronics did the mixing while the water level rose high enough to prime the pump, worked out great.

Best regards!

 

[Dirk]

Whoa, too many impressive things in one picture!! Overload!!! Your gizmo, awesome. The dosing during filling. Brilliant. The deck. The coping. That stunning tile finish. Wow!

Over 8K gals off. Not to mention the percentage that represents in terms of dosing calculations. You can confirm your new number by using Pool Math while keeping an eye on the dosing. Did you catch how to do that in another thread? I recently described it to someone. Let me know if you need help with that...

 

[Hanstb]

Thank you Dirk, we put allot of time and effort into this pool (& house) and we are very happy with the results. The coping was cut and formed on-site from slabs of natural stone, made a mess like you would not believe!

We made allot of changes to the pool during construction, added benches and swim outs, played around with the shape, changed the depth, etc., I believe the 31k number was a guesstimate from the original drawings and was never adjusted for al the changes.

I am confident we measured the fill within 1% of the actual volume, a quality meter was used, I calibrated it very carefully with graduated containers before starting, set the flow within the optimum range for the meter and checked the calibration during and after the fill. The meter itself is being repurposed to measure the makeup water volume directly from the LevelSmart, I can also use that line to measure the water exchange volume when the time comes to adjust down the CH.

I didn't read your post (I'll look for it), but I understand perfectly what you mean, I have already verified the correlation of the water volume and pool math, salt addition was spot on, chlorine and MA additions have also tracked inline with the app. I transitioned to the MA dosing pump and the SWCG yesterday morning and am working on tweaking those systems, very happy with the results so far!

The pool's water chemistry this morning was:

FC - 4 (down 1 overnight)
CC - 0
pH - 7.5 (up 0.2 overnight)
TA - 240
CH - 200
CYA - 50
Salt - 3800
CSI - .74
Temp - 80F

The loss of FC and the rise in pH overnight seem normal to me. I am waiting for the MA dosing system and SWCG to work throughout the day, and we'll see where we are tonight. If anyone sees something amiss, please let me know!!

 

[Dirk]

I'll stay out of the chem-balancing fray, you've already got good eyes on that. Except to say: do what ya gotta do to get that CSI in range. I know you want to avoid further TA-adjusting work/expense. But I fought mine down to around 100 before I let it go and allowed it to find its own way. I may be a bit more fanatical about it than most, but I like the notion that my CSI has always been very close to zero, and only recently have I let it slip negative to accommodate my SWG (between -0.3 and 0.0 is the TFP recommendation for an SWG pool). I try to keep it between -0.2 and -0.1.

0.74 is pretty high. Also, you shouldn't be losing that much FC overnight. Let's see what Marty has to say about that...

 

[mknauss]

A short stint of a higher CSI due to your elevated TA is not an issue. As long as the acid dosing is kept up and the pH is held at or below 7.5 your TA will fall as well as the CSI.

Keep an eye on the FC loss.

 

[Hanstb]

Thanks for the feedback, I believe I misrepresented the FC loss figure!

I took an FC reading yesterday at the end of the SWCG production cycle, FC was 5 @ 4pm. I had an engagement last night which precluded my running the test at sundown, and I was too tired when I got home to test the pool. The FC 4 number is from 08:00 this morning, so that is 16 hours (about two with afternoon daylight), is a loss of 1 FC still cause for concern under those conditions? The pool didn't see any rain, bathers, nor debris of any significance over that period.

I am watching the TA and share your concern with CSI, if time permits, I will do another MA/Blower cycle to help things along.