Another Question - Problems with Alkalinity

[hailypup20]

Sorry to put another post up, but less than a week into things, and already really struggling with the water setup...

We had the electrical work setup on a Monday, which in retrospect was not a good thing as we needed to fill in order to test, but with a busy week of work for my wife and I, it didn't really give us the time to really go at the water chemistry.  I was continually adding sanitizer, only to have it reduced to 0 or near 0 each subsequent test.  Alas, I couldn't beat the high Ph levels, and my TA was off the charts as well.

On my other post, I received the advice of going at the TA first, and being the weekend, I set out to do so.  I stopped at our 'local' pool/spa store, and told the salesperson my issues.  He advised me to use muriatic acid to bring down the TA first (and his advice otherwise was the same...get the TA in check, then the Ph will be more controllable, and then your sanitizer won't disappear).  He said to add 3-4 oz every few hours, testing the water to see when it came down to a respectable level.

So, we have so far added 1 1/2 cups of muriatic acid, in 4 oz doses.  We have been adding it directly to the spa, and then turning on the jets for 20 mins to circulate it properly.  Although we might have seen the TA drop into the 180-240 range, it isn't dropping very quickly, and our Ph is still in the highest range of the AquaChek strip (> 8.2)

I guess what I'm checking to see is whether or not we should be doing something differently, and if so, what.  I'm an intelligent guy, granted not a chemist, but I would have expected my Ph to drop a bit after adding 1 1/2 cups of muriatic acid in about a 6 hour period (and thought the TA would drop a bit more as well).  I've added a whole 16 ounce bottle of Ph Down earlier in the week, and some other Ph Down granules at nights during the week.  We're very frustrated, as we've seen a couple pieces of tissue-like material floating in the tub and are concerned that the quickly dissipating sanitizer has allowed for some undesired growth already...

Again, we have a 2010 Cameo, and are utilizing the Sun Purity filter and have a ozonator as well.  Any advice would be welcomed.  My apologies if I'm over-posting, but the advice so far has been helpful...

[chem geek]

1-1/2 cups of full-strength Muriatic Acid (31.45% Hydrochloric Acid) would lower the TA in 350 gallons by 134 ppm.  Perhaps you are using half-strength (15-16%).  16 ounces weight of dry acid in 350 gallons would likewise drop the TA by around 133 ppm.  Perhaps your spa is larger than 350 gallons.

You say you are using test strips.  They can sometimes be very inaccurate.  Drop-based tests are more accurate.

As for the pH, with aeration of the water, the pH will rise with no change in TA so the combination of adding acid and aerating will lower the TA.  Eventually as the TA gets lower, the rate of outgassing of carbon dioxide slows down so the rate of pH rise will slow down, but it sounds like you are not there yet.

The tissue on the water surface could be white water mold.  It usually won't form if you maintain proper sanitizer levels.  Did you ever decontaminate your spa before its first fill of water and use?

[hailypup20]

Thanks for the reply...the spa is approximately 450 gallons.  It is 31% HCl (has other information on the container, but that is what I remember...) so I was using full strength Muriatic Acid...

I did a number of internet searches last night, and got comfortable with the fact that the aeration will help the Ph rise, so if you're just looking to lower TA, to simply add the acid and get some form of aeration going.  Most of those posts were intended for pool owners, where aeration isn't as natural as it is for a spa.  We simply wanted to ensure it mixed properly and didn't sink to the bottom and cause any corrosion, as we obviously want to lower our Ph along with the TA, but want to focus on the TA to make the Ph more stable.

Please recommend a drop based test kit.  I understand the intrinsic inaccuracies to these strip tests (which are aside from the fact that they can be damn hard to read), but the TA has continually been in the highest level...once it might have been in the 2nd highest color category (so even if it is off, I have a hard time believing that it is off every time).  So in other words, I really don't know how high it might have been.

As for decontaminating the spa BEFORE filling...simple answer, NO.  No mention of anything in any of our Sundance literature other than possibly one of these treatments to the shell to keep it shiny.  Is it possible this had formed in the past (I know they claim to fill their spas for testing twice before shipping out)...again, both my wife and I are scientists (not specifically chemists) and having never been spa users, we were a bit shocked to see some issues so quickly, even though the Cl levels were being depleted so quickly after adding sanitizer...  What should I have done prior to initial fill?!?

Guess one other question, though we're far away from getting to this point...how long after adding Muriatic Acid would it be safe to enter the spa?  I'm still a product of when I was a kid and the neighbor added straight Chlorine to the pool and we had to wait a day or more to get in.

[hailypup20]

Quick update...just tested the water...the color on the test strip for TA finally had a 'definite' change (in other words...we were sure it wasn't at the highest level, unlike other times when it may have been a shade under the highest level, or our eyes were just hoping).  We're assuming it is between 120-180 (probably closer to the higher end), so we just gave it another 1/2 cup of Muriatic Acid.  Hopefully by this afternoon it tests at or just under 120, and we can start to work on the Ph. 

Still appreciate any thoughts you may have on this issue.  We didn't see any of the white tissue stuff (was small floating pieces, and not many of them), so could the acid be having an effect on that?

[chem geek]

Since the white stuff is going away, perhaps it wasn't white water mold but was instead calcium carbonate scale.  Getting the TA and/or pH lower (or Calcium Hardness lower, but you aren't changing that) would dissolve scale and prevent its formation.

You didn't say how you are sanitizing this spa -- chlorine, bromine, something else?  The best drop-based test kit for chlorine is the Taylor K-2006 though for a spa this has more than you need -- nevertheless, you do get what you pay for.  It uses a FAS-DPD chlorine test that lets you measure both Free Chlorine (FC) and Combined Chlorine (CC) to within 0.2 ppm with a 25 ml sample size (or 0.5 ppm with a 10 ml sample size) and does not bleach out at high FC levels (unlike standard DPD chlorine tests).  This is useful when shocking at higher chlorine levels or performing an overnight chlorine loss test to determine chlorine demand.  A comparison of this drop-based test vs. test strips is in in this post.

As for decontaminating your spa, the process is described in this post.  Because spas are generally wet-tested, they often have water leftover in the pipes and significant biofilms can form.  One can also use Spa System Flush (or here -- same product even though the packaging is different).  Even after using such a product and decontaminating, expect that your first fill of the tub won't have the water last as long as later drain/refills.

As for maintenance using a sanitizer, this depends on your sanitizer and you can read about Using Chlorine in a Spa or Using Bromine in a Spa.  Many people using chlorine just use Dichlor-only whereas the link I gave describes using Dichlor-then-bleach to prevent the buildup of Cyanuric Acid (CYA) and be able to have the spa water last at least twice as long and stay clearer during that time and reduce the risk of bacterial growth and hot tub itch/rash/lung.  If you go with Dichlor-then-bleach, then I recommend not only maintaining a low TA level, but also using Proteam Gentle Spa (i.e. borates; boric acid) in order to provide greater pH stability.

By any chance are you on well water?  Your initial TA was extraordinarily high unless you added some sort of TA increasing product (i.e. sodium bicarbonate; baking soda) on startup.  Your Calcium Hardness (CH) may be high as well and this can lead to scaling if you are not careful, especially if the pH gets higher as in your situation.  The white flakes may very well have been calcium carbonate scale though usually it's more solid -- you described "tissue".  If the flakes are like tissue paper and completely fall apart when you try to remove them from the water, then that is more likely to be white water mold.  Anyway, if your TA and CH are both very high for your fill water, you might consider filtering your water using a water filter (ion exchange resin) to reduce the CH (it will also reduce metals such as iron if they are present).

[hailypup20]

Ok, we got the TA down to about 80, and after adding 5 TSP of Ph Down granules, the Ph appears to be near 7.2 after a couple hours of rest and not turning on the jets...

We are sanitizing the spa with chlorine, with the help of a Sundance Spa Purity filter (metallic silver), and an ozonator.  We are indeed using Dichlor-only at this time.

As for needing to decontaminate a spa before truly using it, that thought never crossed my mind, though it does make sense since Sundance hypes their product as being wet-tested 'not once, but twice'.  My concern is the fact that the temps are decreasing (near Chicago, IL), so we'd have to do a spa refill very soon.  I briefly looked at the links you provided for the superchlorination of the spa, and was shocked to read to increase the chlorine to 100 ppm...should that read '10 ppm' (step 3).  My other question with this link would be on Step 13 - by circulating the spa 8-12 hours, that does not mean 'run the jets'...just the natural circulation of the spa itself, correct?  We may do this, even if we get things in order here, just for our safety and peace of mind...though I might see how stable our FC levels are for the week and do it next weekend if the weather cooperates. 

Our Cyanuric Acid (fyi) shows it in the ideal range for the stabilizer...that has been the one area that looks good!

We are not on well water, but we do have very hard water (recently installed a water softener after moving in a couple years ago...our 'hardness' was approximately 25, though I'm not sure on what scale, when we had it tested.  I can be 100% sure I didn't use any TA increasing product upon setup...just a metal control and some dichlor (along with the attempts to initially lower the Ph that were not fruitful). 

And the flakes were definitely 'tissue-like'...again, not many, but maybe the acid killed off what was in the spa.  I'm guessing if we continue to see them, that the sanitation/decontamination process you have recommended is our best bet to get rid of them.  The few things I have read on the mold make it sound like hell to get rid of...would this have likely been an issue before we even received the spa if we saw them about 2 days after filling?

chem geek...thank you very much for your time, expertise and internet links...I'll probably look to order a drop kit sometime in the next couple days!  I'll probably wait a couple hours from now, test the water again, and start to work the FC levels up and see if they can remain somewhat stable with nobody utilizing the spa...

[chem geek]

I forgot to answer your question about how soon you could enter the spa after adding chemicals.  If you have good spa circulation, then 10 minutes should be fine, especially if you run jets to really get circulation going quickly (run the jets AFTER adding the chemical -- you don't want chemicals splashing into your face when you add them).  In a pool, with decent circulation a half-hour is plenty (an hour if you don't think the circulation is very good).  I've done dye and FC tests in my pool where after 10 minutes it's mostly distributed though you still measure changes until around 20 minutes, but my pool has good circulation.  I don't know where you get that you have to wait a day -- that should not be necessary.

That wasn't a misprint of the chlorine level.  To remove biofilms it takes a very high chlorine level, though this is only done for some hours.  Also, the high FC when using bleach has the pH be high so the actual active chlorine level isn't really that high -- closer to 17 ppm equivalent FC at pH 7.5.  Using Dichlor instead doesn't have the pH rise, but increases CYA which reduces the active chlorine level so it's closer to around 15 ppm equivalent.  If you use Spa System Flush, you may not need to use the high chlorine decontamination though doing both gives a one-two punch for both biofilms and to kill bacteria very quickly and thoroughly -- something that those who have had hot tub itch/rash/lung want to do.

The "circulation" in the last steps that take longer means the circulation pump, not the jets.  The jets are cleaned out earlier in the process.

Yes, if you do a chlorine demand test then you can see if your tub is behaving "normally".  Just note that while a usual chlorine demand (with no bather load) in a hot spa is a loss of 25% of the FC level over 24 hours, this is without an ozonator.  With an ozonator, you could see 50% loss.  An ozonator is great when the bather load is high and will reduce chlorine demand in that situation, but with no bather load the ozone ends up using more chlorine oxidizing some of it to chlorate and possibly accelerating some outgassing.

As for CYA, note that for every 10 ppm FC you add using Dichlor, it will also increase CYA by 9 ppm.  So it will build up quickly if you keep using Dichlor and the chlorine effectiveness will drop as a result.  After a month or two, for spas without an ozonator, the water may get dull or cloudy an require shocking; with an ozonator you might not notice that but the sanitation level will be lower (something you cannot see).  With Dichlor-then-bleach, you avoid this problem.  You would still use Dichlor for about one day per month (after the initial first week) since CYA drops around 5 ppm per month.

The 25 hardness is probably in "grains per gallon" and is equivalent to 430 ppm calcium carbonate (Calcium Hardness) which is high.  So with high TA and pH, you were very likely seeing scaling in the water.  Not sure why you saw "tissue-like" flakes that would fall apart so readily, but it's gone now and I wouldn't worry about it.  The decontamination will certainly kill off anything that might be growing in the tub.  White water mold is actually easy to prevent with proper sanitation -- it's usually Baquacil/biguanide/PHMB sanitation systems that have that problem because they aren't as strong as chlorine or bromine against that mold.

[hailypup20]

Ok, update time (if I'm boring the heck out of people, my apologies, but I want to learn as much as I can)...

1)  RE: waiting a day...I was simply reminiscing about my childhood...the neighbor guy used to put in Cl and tell us we had to wait a day for it to be safe...looking back, I'm pretty sure that was his way of saying 'I don't want to deal with you boys today', but it still stuck in my head.  I'm comfortable with the fact that I can jump in the spa at pretty much any time when adding dichlor, etc, though was a bit unsure with the 31% acid.  What level of Cl is simply 'too high' to enter the spa?

2)  Ok, 100ppm Cl for the decontamination...I don't think I'm at that point yet, but I will be if we see anymore of that tissue-looking junk, but I want to learn for the future, as it seems to make sense to do that every so often when you're already planning on emptying the spa.  Is the 100 ppm 'free' Cl or 'total' Cl?  If so, do some of the drop kits give you readings that high?!?  (btw, was researching the test kits a bit last night and plan to order one later today if I can get out of work at a reasonable hour)

Ok...still using the test strips, we put in about 3 TBSP of dichlor yesterday at 1430L and about 10 mins later took a reading and it was at the highest level (10ppm)...tested again 3 hrs later (1730L) and was still at deep purple (10 ppm...so we were likely well above 10 ppm at 1430L).  Anyway, figured I'd let it ride overnight, and tested it this morning, 14 hrs later (0730L), and we were near 3 ppm...so a good 70% drop.  I'm guessing we still need to drop the pH since the FC is dropping faster than would be expected, even w/an ozonator.  Please note that we didn't use the spa at all last night...and our pH appeared to be near 7.8 (so hard to read the pH on these strips), the TA was near 80, and the CYA in the ideal range of 20-30. 

Thought is to head home, and try to drop the pH a bit more, knowing that when we start to aerate, it'll rise again, and also try to push the Cl back up near the 8-10 range.  Is it safe to try the spa tonight and see how much the Cl drops during a 20-30 min soak, or should we be more concerned with getting the pH down and the FC more stable before entering.  I know my wife really wants in after a day at work, but she's more concerned about getting this done right (as am I obviously!)

Any issues with adding dichlor shortly after pH down?

Thanks again!!!

[chem geek]

As for what chlorine level is too high to enter a spa, the answer depends on how much Cyanuric Acid (CYA) is in the spa.  If you have 30 ppm CYA, then 10 ppm FC would have the same active chlorine (hypochlorous acid) level in a hot (104ºF) spa as 1.6 ppm FC with no CYA.  This is probably a reasonable limit as it is about as bad as many commercial/public indoor pools.  However, being a spa, you'll very likely notice the chlorine smell so it's not something to do on a regular basis.  Many people start their soak with around 1-2 ppm FC which with 30 ppm CYA is not very noticeable in odor.  These people generally add sufficient chlorine after their soak such that it measures 1-2 ppm FC again at the start of their next soak the next day (or two).

The 100 ppm would be FC at least initially, but you don't need to worry about measuring it.  Just add the proper amount of chlorine.  You can use The Pool Calculator to calculate dosages; just make sure you change the size in gallons or liters as appropriate!  The FAS-DPD drop-based test kit I recommended can, in fact, measure up to 50 ppm FC, but again I wouldn't bother measuring after adding for decontamination.

3 tablespoons of Dichlor in 1430 liters (378 gallons) is about 18 ppm FC.  So the drop to 3 ppm 14 hours later is a huge drop.  This probably indicates you've got organics or other substances in your water -- either that or your ozonator is extremely powerful (I haven't seen an increase in demand by that much so I think it's far more likely that you've got substances to oxidize in the spa, possibly on surfaces that the ozonator won't do anything about).

You will find that the pH is more stable when the TA is lower, especially if you use a hypochlorite source of chlorine (bleach or lithium hypochlorite).  Don't go below 50 ppm, however.  If you do go the Dichlor-then-bleach route and have a low TA, then you should consider using 50 ppm Borates from boric acid as found in Proteam Gentle Spa.

You can try the spa tonight, but you probably don't want to raise it above 4 ppm before your soak.  Yes, you will use up a lot of chlorine during the soak, but you can add more right after the soak.  If you didn't have an ozonator, every person-hour of soaking at hot spa temps would use around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS).  With an ozonator, it may take half these amounts of chlorine.  These amounts in your sized spa are roughly 6.5 ppm FC so maybe with the ozonator your chlorine demand will be around 3.2 ppm FC.  Of course, you've got much higher demand than that even when you aren't soaking.

You can add the Dichlor shortly after pH down assuming you are adding it over a return flow so that it gets circulated.  You could always add it at a different place in the spa.  Things really do mix fairly quickly -- just don't dump in one thing and then dump another within seconds just to see what it would do -- chlorine plus acid produces chlorine gas.

[hailypup20]

Thanks again for the response...was still holding firm at 2-3 ppm FC when I got home and checked it about 1830L last night, so again, maybe an issue of misreading the test strips (and I've ordered one of the Taylor kits...pricey, but if it means less stress and less chemicals, I figure it will pay for itself in time). 

Added a bit more FC and some pH down, and this morning I'm at about 7.2 pH and 3-4 ppm FC.  If I still have about 2 ppm FC tonight, we'll go for a soak, assuming we've got things in pretty good check.  The TA is holding steady around 80, and the CYA is about 20-30 still. 

I have some Spa Perfect that our dealer gave us and recommended we add about once a week.  I did not add any this weekend, as we were more concerned with the TA/pH issues, but I'm hoping that might help with some of the organics issues we might have.  Still, no more of that white junk since we started going at this, and I would expect to see at least some by now after running the jets and blowers on multiple occasions for circulation...

Again, many thanks for your time in putting together your responses!

[chem geek]

Yes, Natural Chemistry Spa Perfect is an enzyme product that should help reduce the amount of organics in the spa, even on surfaces.  It's not as fast against biofilms as a full decontamination or Spa System Flush, but could still help over time.

Though the drop-based test kit is not cheap, it's definitely a situation of "you get what you pay for".  You can see a demo of the FAS-DPD chlorine test here.  Even a color blind person can use the test.  You can see a demo of all tests in the K-2006 kit here by selecting the "Pool/Spa" category on the left and then look at the videos under K-2006 below the video window.

The cost per test is fairly low since you only need to buy replacement reagents and you don't perform most tests very frequently.  You usually test FC and pH the most (unless the pH is stable) and only test CH after a refill and TA perhaps once a week if you are adding acid.  CYA is tested around once a month until you get a feel for its slow drop over time (usually around 5 ppm per month).