First time owner - does this sound correct

[mrwoo]

Hello. Great site here. I think I've got a handle on this, but let me share and see.

I have a tub coming within a couple weeks. My water tests show the following:

Total Alkalinity is 240ppm. This is actually 240ppm CaCO3 as per my Hach digital titration method using both phenol and bromcresol. I appear to have a lack of other alkaline species. The Taylor K-2005 and the TF-100 kits both return the same results within 10ppm.

Calcium Hardness is 100 with an AquaChek strip, 120 with the K-2005 and 250 with the TF-100. I redid the test 3 times, both using the comparator and the little taylor mix plate. The kits were bought within a week of each other, maybe it's a reagent out of date? There is no detectable chlorine so I don't know what is causing the differences.

pH is 7.4-7.5 with the probe I bought with the TF-100 kit. Freshly calibrated. My other two probes, one a gel and one an inline, both calibrated with 3 points also show 7.5. The K-2005 and TF-100 look like 7.6. The AquaChek strip says 8.4 lol.

Here is my plan then.
Fill new tub with water and Ahh-Some and Dichlor to > 10ppm. Run and do another 1/2 dose Ahh-some. Drain and rinse.
Fill tub again, shock with Dichlor to > 10ppm. (Also using Dichlor to yield 30ppm CYA)
Start adding muriatic acid to bring TA down to < 100.
Run jets to bring pH to 7.6+-
(repeat till TA < 100 & pH 7.6+-)
Put Saltron SWCG in place and monitor salt levels, pH and FC/TC levels.
Keep fiddling with the above until a static level is reached.
Monitor pH and chlorine levels as using tub to see what the rate of useage are for the FC and TC.
EDIT: forgot to mention I will be using liquid bleach to supplement the SWCG

I have no idea what to do with the CH. There is some there for sure but I can't find a reason for the two titrations to be so different.

Am I missing something? Is a step out of order?

Thanks for any advice.

 

[kimkats]

Calcium Hardness is 100 with an AquaChek strip, 120 with the K-2005 and 250 with the TF-100.

I would just throw the strips away. Not even worth the time it takes to take the top off to get out one.

Where did you get the K-2005 from?

TF-100-if you got this within this year I KNOW the regents are good as the company is VERY good about rotating and disposing of out of date stock or even close to out of date stuff!

So I would trust the results from the TF-100 and go from there.

Kim

 

[YippeeSkippy]

I would use the Ahh-some and drain.
Then I would super chlorinate and drain again.
Only then would I fill the tub and tweak the water for actual use.

Maddie

 

[mrwoo]

Thanks for responding. I got the 2005 kit off amazon. All the reagents are dated "best by" in late 2021. The K1000 and K1766 kits I bought with my TF-100 are dated mid 2021. I have no idea what that means other than there should not be differences in titrations of these reagents.

Regarding fills and drains, am I correct that I want to have the tub to temperature before adding Ahh-some or shocking it?

 

[DangerBoy]

I see you're in Kalispell, MT. Your water comes out of the Rockies just like ours does just north of you in Calgary, Alberta. Those mountains are largely made of limestone so our rivers flow over a lot of limestone and pick up a lot of Ca, Mg and HCO3 on their way out of the mountains. As such, the water has to be of the Calcium/Magnesium Bicarbonate type and couldn't be of the sodium bicarbonate type which you would need to have in order to have lower CH than TA*. You would therefore expect your water to have high TA and CH which is exactly what we have here. Ignore the test strip result; it makes no sense with the water type you have. The correct CH reading is 250 ppm or thereabouts.

Note: * This is assuming you're not running your water through a softener. If you are, the test strip result is the more plausible of the two.

Another way you can verify this is call your city's waterworks department and ask them for the latest mineral/routine water analysis test results for your drinking water. They do those tests regularly. My city publishes info about our water's mineral content levels on its website and will provide citizens with the latest test results upon request. This is good info to have as it allows you to cross check your initial test results with your City's latest tests to assure yourself you're getting good data/plausible results.

Our water, which will be very similar to yours, has moderate to high TA and CH levels with those numbers being lowest in the spring/summer when the rivers become somewhat diluted with rainwater and surface runoff and highest in the dead of winter when there's little to no storm runoff to dilute the water coming out of the mountains. I suspect the same pattern will apply in Kalispell.

 

[YippeeSkippy]

I got the 2005 kit off amazon. All the reagents are dated "best by" in late 2021.

I don't believe the K-2005 contains the FAS-DPD powder test for the FC and CC...right?

If you order just that test from tftestkits.net your kit will be the same as the K-2006 we recommend. You *really* need that FAS-DPD for accurate readings *over 5ppm* and determination of CCs.

Maddie

 

[mrwoo]

After a lot of testing I feel these are accurate values for my water
TA 240
CH 240
pH 8.2 (this does flucuate between 7.8 and 8.2 seemingly daily)

Got my new tub. Added dichlor to 10ppm approx and used Ahhsome. Lot's of foamy suds but really it was not dirty. Hardly anything to wipe up or out. Refilled tub, added about 5ppm dichlor FC. Started the MA routine yesterday afternoon. Took about 15 minutes for the pH to rise from about 7.3ish back to 8.2. Kept at it and after a few hours my TA is at 40 this morning. May need to add some baking soda.

Used the tub for 3 hours, 1/3 time with jets, two people. Consumed all the FC. Put bleach in at end of night, this morning sitting at 2-3ppm FC. But the pH was at 8.

Here's the question, if the TA is at 40, how does one bring pH down without dropping TA even further? I don't know the point at which TA of 425 gallons of water will become too volatile. Is the CH value of 240 contributing to the pH? Further, is the CH contributing to calcium scale at high temps and pH?

I've read the stickies and a Crud ton of other info, but don't really understand what product to use in this situation. I'll use my saltron mini swg later but I wanted to see how this all works first. I did order some proteam spa guard boric acid to help but I really wanted to understand what this all indicates. Could it be lack of enough CYA?

Thanks.

 

[kimkats]

Down towards the middle you will see we use baking soda to push TA up: Recommended Pool Chemicals - Trouble Free Pool Using PoolMath you will know how much to add.

 

[mrwoo]

Thanks for responding.
It might have taken a few hours for things to settle out but last night after work I had:
7.88 pH
50 TA
1.5 FC
.5 CC

I added:
2.4 tsp dichlor (brings CYA to about 4ppm so far)
2 tsp Muriatic
pH dropped to 7.2
50 TA

After 5 hours of no use:
8.1 pH (freshly calibrated meter with a new probe)
50 TA
5.5 FC
.5 CC
After 1 hour use with jets:
7.9 pH
50 TA
2.5 FC
.5 CC
Add - 1.2 teaspoon dichlor (0.2 oz) and 1 teaspoon Muriatic
Tested 7 hours later this morning:
7.78 pH
50 TA
4.5 FC
.5 CC

I understand the chlorine is chewing up contaminants and is consumed and there will be some CC's, and that using dichlor replenishes the chlorine and builds the CYA. I also understand that a certain level of CYA is good for the volatility of the chlorine load. What I don't understand is just what to do about the TA. It's at 50 or very close. I've done the TF100 titrate test a dozen times and I also used thiosulfate with my Hach digital titrator (thiosulfate I am pretty sure is what is being used by taylor as the 2 drop first step, then H2SO4 till pH changes at red/pink).

Anyway, I can keep adding acid to neutralize alkalinity and bring pH down. But how low can one actually go and still have some buffer left? Is this a game of add a teaspoon at a time as you get that close? And further, if acid will be required periodically after using bleach for chlorine, what is adding alkalinity? Does one have to monitor the TA and eventually add bicarbonates back into water so as to keep using acid to bring pH down as it drifts up?

I am most certainly splitting hairs here, but it seems there must come a point of equilibrium where the pH stays at the optimum level. I can overshoot with the acid but would rather understand what really happens and go slow and have the results be anticipated. Thus far I've read so much here that it's been pretty easy and expected as I brought the TA down.

Thanks for anyone's input.

 

[kimkats]

The small size and nature of a spa/hot tub your pH is going to rise and fast. The jets alone will drive it up and fast. I am not sure if anyone finds a sweet spot on the pH/TA in one BUT I do not have one so I really don't know. Use baking soda to bring the TA up. See if having your TA higher makes your pH happier and more stable.

 

[santacruzpool]

TA at 50, or even a little under, in your hot tub should be just fine - mine settles there as well and the PH is much easier to manage from that point forward. For me the PH sits around 7-6-7.8 after I get the TA down to 50 - over time if PH does creep up a little, then I will still add a tiny bit of MA and on occasion my TA will measure 40. I don't adjust it and just let it be. Typically the next time I check the TA is back to 50.

 

[mrwoo]

Thanks for the replies. It would seem that it takes some days for a given TA to settle out. I was reading 40 and now a couple days later am at 60. In my case I am neutralizing a lot of calcium bicarbonate so if the TA is going up I wonder how it does and what it is. It could just be that it takes that long for all the water to find equilibrium. I did turn off my ozone and modified the pump to circulate for 30 minutes every 8 hours. Perhaps between the ozone running when the pump ran for 3 hours per day it is influencing the TA rise. Who knows.

As of now after 5 days I have my pH sitting under 8 almost all the time, and CYA up to about 11. Will see what happens after the CYA is around 20 and decide on boric acid. I will probably reduce TA a bit more to get to 7.6 and see if it holds there.

Waiting to use SWCG until I better understand all the reactions taking place.

@kimkats - I don't know for sure if it applies to the chemistry in a hot tub of water, but the alkalinity in an aqueous solution plays a major role in pH for nutrient uptake. I would assume it's the same, but I'm no chemist. What I do understand is that, just as some information to visualize, water with high alkalinity (typically calcium bicarbonates) will eagerly be attracted to charged sites because the calcium as a strong charge (valence). So if your pH is perfect, but high alkalinity, the pH has no real affect. It's only a measurement but because of excess alkalinity typically the pH would drift high with it. I don't remember a lot of it now but we had to completely stop neutralizing our water to a pH of 5.8 because in doing so we drove the alkalinity down to 0, which made it very easy to cause burns in plants (too much salt). The alkalinity needs to be about 80 to 100 for optimum buffering of fertilizer salts to plants. Once we started adding H2SO4 to get 80ppm alkalinity the growth became better and more predictable, because the pH did what it wanted but the buffer was sufficient to prevent either too much or too little uptake.

That's what I'm trying to understand with tub water, is it really the TA to watch as too little allows rapid pH swings, or is it more pH focused and safe to ignore TA to some extent because there is nothing "live" to damage. I wish I had not gotten into a higher up position and went to the office because I would still know all this stuff lol.

 

[jseyfert3]

That's what I'm trying to understand with tub water, is it really the TA to watch as too little allows rapid pH swings, or is it more pH focused and safe to ignore TA to some extent because there is nothing "live" to damage. I wish I had not gotten into a higher up position and went to the office because I would still know all this stuff lol.

I see a lot of things talking about how the TA is a buffer that prevents pH swings. This info is in my spa instructions, the Taylor test kit, etc. That may be true, but the reading here my understanding is that for a particular water source, there is a equilibrium in pH at a specific TA. For most people, they ends up being a pH of mid 7's at a TA of ~50 ppm. This equilibrium takes aeration to reach. A pool is often not in a state of equilibrium, due to lack of forced aeration. This is typically fine, as there is just a slow increase in pH requiring acid additions once or twice a week. But since a spa has forced, very vigorous aeration, it reaches this state of equilibrium very fast, in 15-30 minutes or so. This is why for a spa the acid-aeration to immediately knock the fill TA from whatever it is down to ~50 ppm is so important.

50 isn't a hard limit. If the pH is good and steady at a TA of 40, then run 40.

How I see it the TA is a guide during the initial fill water balance. I start with a TA of around 300 ppm, so I need to do a lot of acid and aeration to get it down to roughly 50 ppm. During this time I watch the TA to monitor how close I'm getting. Once I'm down to 60 ppm TA or so, I pay less attention to the TA and just add acid to target a pH of 7.4 or so. Pretty soon the pH is nice and steady, and my TA is whatever it is to get that steady pH without me actively trying to adjust the TA level. Ultimately, the steady pH is what you're after, not a specific TA level.

Also, check out the extended test kit directions. When I first started doing the Taylor test, I would stop when it turned red. However, the extended test kit directions here state to continue until no more color change is noted, and don't count the last drop that caused no more color change. For a 10 mL sample (I usually always do a 10 mL sample for TA/CH), this usually meant adding one extra drop which took it from a dark red to a nice bright red. Instead of 40 ppm TA, I started reading 50 ppm TA.

 

[mknauss]

(I usually always do a 10 mL sample for TA/CH),

Be aware -- a 10 ml sample results in each drop of reagent to the end point counting for 25ppm. So I would not suggest that when testing TA below 150 ppm or so.

 

[jseyfert3]

Be aware -- a 10 ml sample results in each drop of reagent to the end point counting for 25ppm. So I would not suggest that when testing TA below 150 ppm or so.

You are right, I had a brain drain. I switch to a 25 mL sample around 100 ppm for TA.

 

[mrwoo]

I've noticed that as I would add acid and drop the TA, it did indeed become very stable at 7.3-7.5. During a soak it could come up but it was only about 7.7ish. I have been quite suprised at how stable it has been. I've stopped testing TA at this point and simply watch my pH every day. It has only gone up when I have topped it off with fresh water, and it's been super easy to fix.

I cannot imagine why bleach and acid are not easier than the products that came with my tub... ph up then down then shock then clarify then rinse and repeat. I know that it works as lot's of tub owners do it and have for a long time, but from the perspective of keeping the water in the optimal spot for tub lifespan, it seems like such a better way.

But I am still a neophyte so who knows.

 

[jseyfert3]

"Works" is relative. I've been here long enough to see many people join because they are frustrated and don't understand pool/spa water chemistry, and can't keep water clear and/or algae free. Honestly, like most who have been here long enough to see what proper water care is, I have reservations about getting into public pools, and especially public spas now. The general public and the pool industry in general doesn't understand proper water care, and even if the water is clear (which is often isn't), clear water doesn't mean safe water!

Not only that, but the typical and repeated use of tricolor and dichlor will eventually make chlorine ineffective, and if not watching the TA/pH they will eventually remove all TA from the water, tank the pH, and cause major corrosion to any metal parts. For a spa that's typically limited to the heater. Not good.

The methods outlined here, with proper testing, chlorine, and muriatic acid, will certainly prevent damage to metal and maintain safe and sanitary water. We've had an inflatable spa filled on and off for 2 years now. The only time I've ever had anything but crystal clear water was if I got lax during a period of non-use and didn't maintain the proper FC level. Otherwise, perfectly clear water with rock solid pH and the only things I need is CYA, bleach, muriatic acid, and of course a high quality test kit. Nothing could be cheaper or easier overall, except a SWCG! And yes, our future pool will be getting a SWCG this summer! I also plan to add one to our spa at some point.