Switched from BBB to Bromine in Spa

[chem geek]

If you are using bromine tablets, then these may be acidic for the same reason that chlorine usage/consumption is acidic. If you were to get most of your bromine from reactivation of bromide to bromine by shocking with an oxidizer such as chlorine or non-chlorine shock or an ozonator, then the pH would theoretically be more stable.

With net acidity, the pH and TA would go down, but with aeration the pH would go up so the net result would be seeing the pH stable or rising while the TA would be dropping slowly over time.

 

[BCHWB]

Ahh that explains it. I only use the tabs/floater occasionally now. That's why I don't see the TA slowly dropping over time. This is all making sense now. So how many times can I reactivate the same bromide bank? Is this an indefinite loop thing or does my bromide bank diminish over time?

 

[BCHWB]

This is it. The sisters are here and they're planning on spending quite a while in the tub. I've shocked the bromine up to 9.5ppm and adjusted the TA up a bit. I'm at pH7.6 TA 60 and CH 190 right now. I'm sure they'll drive the bromine down to 0 and the pH up to 8 during their stay in the tub and I'm not sure that's the worst thing in the world provided I shock the Crud out of it right after. I'm thinking like 2 to three oz of lithium hypo will do the trick. Usually i use 1 Oz. after my wife is in there for 1/2 to 3/4 of an hour.

Edit: don't get the wrong impression, the stars are for the word cra* and not the other one.

 

[chem geek]

The bromide bank is mostly recycled, but you do lose some bromine that outgasses over time or that gets carried out in swimsuits, etc.

As for shocking to get rid of bather waste, the rough rule is that for every person-hour of soaking it takes 3-1/2 teaspoons of Dichlor, 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS) to oxidize the bather waste. For lithium hypochlorite, this is about 5-1/2 teaspoons (almost 1 ounce). Note that bleach would work just as well as lithium hypochlorite and is far less expensive -- lithium hypochlorite is about 5-6 times as expensive as bleach for the same equivalent chlorine addition.

[EDIT] I corrected the following which was wrong because I was thinking of 1 ounce as 1 teaspoon -- doh! [END-EDIT]
1 ounce of lithium hypochlorite would normally handle 65 person-minutes of soaking so that was probably more than enough for the 30-45 person-minutes of soaking your wife was doing. I would expect less to be needed, especially since you have an ozonator that should be taking over some of the oxidation of the bather load. I wonder if 1) your ozonator is actually working and 2) if the lithium hypochlorite you are using is the typical 29% by weight (35% Available Chlorine). If your ozonator is working, you should find that even when you aren't using the tub, the bromine level is maintained or even increasing since the ozone should be reactivating the bromide to bromine.

Richard

 

[BCHWB]

They're out! The bromine level was nearly 0 when they got out.

I shocked it with 2.5-2.7 oz of Lithium Hypo which is low by your rule as they spent about an hour in there and the bromine level shot up to about 16 or 17 ppm. Maybe I'll shock it up again tomorrow morning. The ozinator seems to be working. It will maintain the bromine level at about 4 to 5 ppm on it's own I think. She's in there pretty much every other day and I shock after so it's hard to tell if it's the ozinator or just my natural sanitizer demand bringing it to 5 by the time she gets in again.

It's all balanced now 7.6, 65 and 200 at 102F and I closed it up.

I'm changing this water soon anyway it being the first fill and all...

 

[geekgranny]

If you are using bromine tablets, then these may be acidic for the same reason that chlorine usage/consumption is acidic. If you were to get most of your bromine from reactivation of bromide to bromine by shocking with an oxidizer such as chlorine or non-chlorine shock or an ozonator, then the pH would theoretically be more stable.

With net acidity, the pH and TA would go down, but with aeration the pH would go up so the net result would be seeing the pH stable or rising while the TA would be dropping slowly over time.

Yesterday, I got tied up and totally ignored the spa. The night before yesterday, I stopped struggling and left spa with the TA=10 and pH=6.8, after spending that day battling with wide swings in pH and very low TA. That day I, also, added more borax with a goal at 60 ppm.

Today, just now, things are looking better. (remember I haven't touched it for about 36 hours) (cork still in air feed to return)(only circulation going{tiny amt bubbles} with ozonator{normal amt. bubbles})

Br = 4
pH = 7.2
TA = 10
CH = 250
Borate = 50
Temp = 99
CSI = -1.23 (fiberglass spa)

Pool Cal calls for 6.5 oz baking soda with goal 60 ppm. I'm adding in 2 oz increments with jets running but no venturi, top closed. It's been a few days since I put the bromine float in. (BTW... the problem with low pH was not so much low pH, in mornings before any fiddling it was because the pH was off the scale UP.) So I'm thinking, if I continue to have these pH UP issues, using the feeder some won't be an issue as far as adding to the raise in pH.

The major problem was very wide swing in pH, while trying to up the TA. pH would go way off the scale UP and then I would have to use MA to bring pH down, then TA would start rapidly falling.

I'm adding the baking soda every 30 minutes, but testing pH between additions.

I think there are two major factors........... One was way too much aeration from return, and too much aeration while jets running with venturi while adding MA. Two making adjustments too rapidly even though a huge amount of water is being circulated and mixed.

I'm taking it more slowly today. Will report later. BCHWB, I surely hope the ladies are having a grand time. :-D

gg=alice

 

[geekgranny]

Br = 4
pH = 7.2
TA = 10
CH = 250
Borate = 50
Temp = 99
CSI = -1.23 (fiberglass spa)

Two hours circulation, with 30 minutes jets, no additional air, with only the one addition of 2 oz baking soda, now have:

Br = 4
pH = 7.5
TA = 20
CH = 250
Borate = 50
Temp = 99
CSI = -0.63 (fiberglass spa)

I am seeing that 1) keep as much air out as possible and 2) adjust very, very, slowly.

I'm going to add two more oz baking soda................... wait............................ then add 0.7 oz MA........................... wait........................... then test...................... recheck tomorrow morning.

[EDIT] with water sitting for about 10 minutes in test tube the pH is now 7.8. I think maybe that has been an issue AND I should wait for a few minutes before reading pH test. OTC drop test HTH - half of my reagents are Taylor but still have a some HTH I want to use up. [end edit]

gg=alice

 

[BCHWB]

with 250 CH, once you get the TA up to between 40 and 60 you should be sittin' pretty. That's where I have the easiest time regulating everything.


My wife is in again tonight with one of our girls. Work Work Work...

 

[PaulR]

[EDIT] with water sitting for about 10 minutes in test tube the pH is now 7.8. I think maybe that has been an issue AND I should wait for a few minutes before reading pH test.

The pH will vary a bit with temperature. If you let the water cool off before you check the pH, it can be off by (I think) as much as two tenths.
--paulr

 

[geekgranny]

[EDIT] with water sitting for about 10 minutes in test tube the pH is now 7.8. I think maybe that has been an issue AND I should wait for a few minutes before reading pH test.

The pH will vary a bit with temperature. If you let the water cool off before you check the pH, it can be off by (I think) as much as two tenths.
--paulr

ahhhhhh. :idea: Thanks, It does cool sitting in the kitchen. I'll then trust first reading.

 

[chem geek]

Roughly speaking, if the pH of water is 7.5 at 104F, then it will rise to 7.74 as the temperature drops to 72F. This result varies somewhat depending on CYA level (less of a rise when there is CYA in the water). It does not vary very much by TA level. So you should not wait too long for the pH test if the water is far away from room temperature as is the case with spa water.

 

[geekgranny]

Thanks guys. Just took first reading for day and is looking good. :-D Finally starting to stabilize.

Again, I've learned to add things very, very, very, slowly and with lots of time between adding each individually and testing. Waiting close an hour between additions and testing has been beneficial for me and the spa. Keeping top closed. Jets without venturi for 30 minutes then normal circulation for 30-60 mins before retesting. Will then add a tiny bit of MA if needed. Jets for 30 minutes, normal circulate for one hour. retest

I'll give spa one more day before wo-man hours added to equation.

First Reading Today

Br = 2-----I'm going to put the floater in (several small shards of Bromine) for an hour or two after BS and MA and then retest
pH = 7.5-----will test an hour after addition of BS
TA = 30----I'm going to add 2.6 oz (by wt) BS and check in an hour.
CH = 270 -----I had been checking with 10 ml sample but used 25 ml today
Borate = 50
Temp = 98
CSI = -.39(fiberglass spa)

 

[polyvue]

Roughly speaking, if the pH of water is 7.5 at 104F, then it will rise to 7.74 as the temperature drops to 72F. This result varies somewhat depending on CYA level (less of a rise when there is CYA in the water). It does not vary very much by TA level. So you should not wait too long for the pH test if the water is far away from room temperature as is the case with spa water.

Not sure of the mechanism for this change, but presume that there is some thermodynamic molecular work that transpires to make this so. If a 32° F decrease in water temperature results in a .24 rise in pH, can we deduce an inverse change in the sample's pH given a temperature increase of 32° F? In short, should we expect a decrease in pH (-.24) when the temperature of a water sample is elevated by 32° F? (This would be pertinent when a water sample drawn from a cold reservoir (a 46 degree pool, e.g.) is brought into a heated/conditioned space and not immediately tested.)

Also curious as to whether any predicted change is relative to pH or temperature, or is an absolute measurement. If the sample's pH was 6.0 or 9.7 would the outcome of a 32 degree temp change result in a .24 change to pH? In like sense, is the starting or ending temperature a factor in the change to pH?

Finally, does the sample's chemical composition (level of carbonates or other elements/compounds typically found in pool water) greatly affect the amount of pH drift in the process you describe? You mentioned CYA or I wouldn't have thought to bring this up!

 

[chem geek]

It's more complicated than a simple pH change for a given temperature change. It varies by temperature and by starting pH level. You can use my Pool Equations spreadsheet to figure out the anticipated pH change given starting and ending parameters (presumably all the same except for temp). And yes, the reason for the pH change is the thermodynamics of the various reactions (that is, the variability of equilibrium constants with temperature) including that of water and the carbonate buffer system (and CYA, etc.). So long as you measure pH at the pool or spa temperature, none of these effects should matter to pool or spa owners.

 

[BCHWB]

The Bromine floater in my spa destroys about 15ppm of TA per day in its totally closed position. I'll need another one that's a little more adjustable I think, and to boot it maintains the level at near 8ppm. I'm going to test and see just how low the Bromine level gets with just the ozinator this way when I'm riding a good TA value, the floater doesn't go and waste it all while we're not using the tub.

I just brought the TA up to 65 from 35. My pH was down at 7.5 or so so I was flirting with a -.5 CSI. Now I'm good at 7.6 and 65 and 190CH. Nearly 0 CSI. She'll use it tonight and push the pH to 7.8 or 8 and I'll use MPS to shock after which will push it back down. I've got a nice little routine now.

When does all the stuff I throw in there just make the water into a globulous mass like a non newtonian fluid?