Jump to content

Balancing Ph (Too High) And Alkalinity (Too Low)


nmwolfy
 Share

Recommended Posts

Hi

My water is very low Alkalinity (40-50) and high pH (~7.9 or 8). I can not seem to get the TA up to 80 and the pH down to 7.6. I am using baking soda (sodium bicarb) to increase alkalinity and Spa Down (sodium bisulphate) to bring pH down. bringing pH down brings TA down, bringing TA up brings pH up. Appreciate help and suggestions. If there is an existing thread on this topic, please point me to the comments and wisdom. thanks

Link to comment
Share on other sites

I would suggest reading all of the "pinned" threads at the top of this page first. Many of your questions will be answered in those threads and you will get a good heads up on the questions you will have in the future.

Secondly, I would not do anything drastic to raise your TA just yet. Many of the experts on this forum suggest keeping your TA in the exact range you are at now. I keep my TA right in the same range (40-50) and it has greatly reduced the amount of acid I have to add to maintain pH. Now the pH creeps up very slowly and can take up to a week before I have to adjust it. If the spa gets much use, especially with the aerators on, it will need attention to bring the pH back down but if I know it hasn't been used I can get by skipping a day or two of testing & maybe just throw in a little bleach to be safe. Also, the less acid I have to add, the less TA drop I see so that's even less chemical being used.

Link to comment
Share on other sites

Thanks - I have been reading the Nitro water chem thread and all of the follow ups. Doesn't quite distil down to a target set of actions for my case, but your summary seems reasonable. I did see the pH drift up again over night to above 7.8, so bringing it down sounds like the key target. I guess since I am seeing such direct swings in pH and TA, I am wondering if I should use a different acid or different TA booster. I do use Dichlor, and am still trying to understand (reading) what role it plays in pH and TA ballance.... trying to get there ....

Link to comment
Share on other sites

Kind of sounds like your TA readings are off. If the pH is drifting up that quickly it suggests that your TA is too high. (I assume that you have the aerators turned off while you are not in the spa)

Are you using test strips? The ones I tried were horribly inaccurate - especially for TA. If you are using test strips throw them out & get a good Taylor test kit like the K2006.

Nitro's thread was (and is) one of the best resources I have found. My daily spa maintenance kit contains a Taylor K2006 kit, Clorox bleach, dry acid (sodium bisulfate) & baking soda. I rarely need anything else except Dichlor & metal sequestrant when starting with new water.

Dichlor has little effect on pH & TA except that it adds CYA (Cyanuric acid). CYA has a stabilizing effect on the sanitizer which helps protect from sanitizer depletion due to sunlight exposure. However, too much CYA is not good.

So Dichlor is used as the sanitizer & tracked until the desired level of CYA is reached. Usually 20-40ppm. I aim for 20ppm because my spa is under cover & does not get much direct sunlight. The amount of Dichlor required to get to the desired CYA level can be calculated with the Pool Calculator (www.poolcalculator.com) Then you switch to bleach as the sanitizer because the CYA remains & does not deplete.

I could go into a long explanation of the relationship between pH & TA but it has already been done in the threads you are reading. I think you are on the right track to throw in a little dry acid (Your Spa Down) and get your pH down to about 7.5 - 7.6 while you digest the rest of the info.

Link to comment
Share on other sites

Thanks,

I use a Taylor k-1005 kit. I don't think I can do CYA with it, but I can do all the other tests. I have not been counting additions of Dichlor as suggested in Nitro's thread. I guess I should try that next fill. Just filled 3 weeks ago. In the mean time, I guess I will get my pH to 7.6 and hope the TA doesn't go too low.

Link to comment
Share on other sites

The CYA test is not worth the money in my opinion...very tricky to read accurately.

Pretty much the whole TA vs pH thing boils down to this:

1) Check TA.

2) Add baking soda to raise TA to where you want it (This inherently raises pH)

3) Check pH.

4) Add dry acid to lower pH to where you want it (This reduces TA somewhat)

5) Repeat until both remain at the desired level

They both work against each other but not at the same rate.

Eventually you get to where you want to be on both.

It made me nuts at first until I got the hang of it.

After you reach the initial balance the TA will maintain pretty well.

If it becomes necessary to raise your pH for any reason just use the aerators on the spa.

Chemical "pH Up" products or additional baking soda will throw the whole balance off.

Link to comment
Share on other sites

Perfect - thanks - that's the what I needed - the order in which to do the steps. I am on it and will see if I can stabilize over a few days. Thoughts on what happens if/when I add Aqua Finesse? I have two jugs of it, so will figure I'll use it to keep biofilms down and require less Dichlor/Chlorine

Link to comment
Share on other sites

I have no idea about the Aqua Finesse. I stay away from most of the branded chemical concoctions. I have read too many horror stories on here where people have added brand X chemical to their spa or pool & the water turns purple & grows hair. I pretty much stick with the basic methods. The chemistry is tricky enough for me to understand without throwing in unknown variables. I got 2 years out of my last fill before the TDS got high enough for new water. That's with a 1500 gal swim spa with limited use (wife). One other thing occurred to me last night that you might consider. If you are currently shocking your water or have a high sanitizer level it can throw off the Taylor pH test & give false high readings. Just something to consider.

Link to comment
Share on other sites

Nope ... never shocked it before today. I just brought it up to 10ppm FC. pH was 7.5 (down from before shock) and TA is still only 50-60 (in taylor test, 40 still green, 50 is clear, 60 is red).

I'll test pH later when Cl comes down.

Couple quick additional questions:

I am confused about when to switch from Dichlor to bleach. When Nitro says to add X ppm, are you actually doing a calculation with grams of Dichlor and gallons of tub water? If so, what exactly is that calc? Or just noting the measured ppm of FC, which then drops off, of course. Thanks for clarification on this.

Link to comment
Share on other sites

You switch from dichlor to bleach after you have gone through enough dichlor to leave behind the desired amount of CYA. The chlorine part of the dichlor "burns off" as it oxidizes contaminants (same as bleach) but the cyanuric acid (CYA) component is left behind & accumulates as you add dichlor. I use the Pool Calculator to do the calculations (www.poolcalculator.com). For instance, I am starting with a new fill (1525 gal) & I know I want my CYA level to end up at 20ppm. There is a section at the bottom of the Pool Calculator page, "Effects Of Adding Chemicals". If I enter 8oz of dichlor it indicates that that amount of dichlor will raise CYA by 20ppm. So I measure out 8 oz of dichlor in a separate container & use that as my sanitizer until it is used up. Then I know that I have accumulated 20ppm CYA in the water & I switch over to bleach. The Pool Calculator is a great tool to use to figure out how much of what to add & see what effect it is going to have. I know you have already started using dichlor in your water so at this point maybe you can weight what is left from the container & subtract from the label weight to determine how much you have used?

Link to comment
Share on other sites

Wow - so only 2-3 oz of dichlor in my 400 gal tub and then switch away from dichlor to bleach until the next fill? I tend to add about 1/2 oz / week and I added a full ounce today, so must be getting close. Is there any other indicator of needing to get off the dichlor, like FC dropping off fast or something? The dealer told me to keep FC at a certain level with dichlor (although that is in addition to the Aqua Finesse that he promotes). The bottle of Dichlor (Spa56 from Leisure Time) also suggests keeping FC at 3ppm only with dichlor. Guess I need to read up on what higher CYA does since the program I am on would drive it sky high

Link to comment
Share on other sites

I forget exactly what effect too much CYA has. You probably aren't too far out of range yet though. Plug your parameters into the Pool Calculator then go to the near bottom of the page on the Suggested Goal Levels row & select Traditional Spa. Go back up to the CYA row & it will show you what the suggested CYA level range would be for your application.

Link to comment
Share on other sites

The active chlorine level is roughly proportional to the FC/CYA ratio so as the CYA climbs the active chlorine level drops unless you raise the FC level proportionately. With the CYA building up over time using Dichlor, the same FC means the active chlorine level is lower and that means it more slowly oxidizes your bather waste. If you use the spa regularly, then you can get behind and build up the chemicals from your sweat and urine. The water eventually turns dull or cloudy as a result. Also, at higher CYA (somewhere above the 100-200 ppm range) the chlorine doesn't kill certain bacteria fast enough and the probability of getting hot tub itch/rash/lung increases.

Note that CYA is slowly oxidized by chlorine so will drop by around 5 ppm per month so one usually uses Dichlor for a day or two per month. As for the target CYA level, I used to say 20 ppm because I was being conservative after putting together a table of hot tub rash/itch/lung incidents, but I think 30-40 ppm is fine. Don't go higher than 50 ppm to play it safe.

Note that you should keep your TA low at around 50 ppm and use 50 ppm Borates (say, from boric acid) to have your pH be stable, especially if you use aeration jets while soaking. Nitro's writeup wasn't updated after we discovered that 80 ppm TA can be too high for many spas where the pH would rise too quickly as a result.

Link to comment
Share on other sites

The downside of the CYA getting close to zero is that the active chlorine level will be too strong. So chlorine will oxidize swimsuits, skin and hair faster as a result and will outgas faster to react with hot tub covers and will produce more of the more volatile and irritating disinfection by-products (including nitrogen trichloride).

Link to comment
Share on other sites

  • 1 month later...

One other thing occurred to me last night that you might consider. If you are currently shocking your water or have a high sanitizer level it can throw off the Taylor pH test & give false high readings. Just something to consider.

This is really interesting and might explain the issue i'm having. TA at 50, but PH seems to be stubbornly high. The Taylor PH test maxed out last night and the acid demand test took 5 drops to get to normal PH. I added the required amount of dry acid, and tested again this morning (12 hours later) and the PH test maxed out again and required 2 drops on the acid demand test.

Then I tested for CL and it's at 20PPM FC and zero CC!! Holy smokes! We haven't used the spa at all last week, but I have still added the usual 5oz of 6% bleach every night without even testing. Guess it added up and that's what's causing the false PH reading. I also tried a test strip just for fun and the PH pad is a very weird mix of orange and super bright pink.

Guess I won't be adding any more acid until the CL drops to reasonable levels and I can test properly. Hope my ozonator gets rid of the CL in a few days. (I got about 20ppm CYA in there as well).

Link to comment
Share on other sites

You don't add the same amount of chlorine when you use the spa vs. when you don't. If your spa is 350 gallons, then 5 fluid ounces of 6% bleach (are you sure it's still 6%? Clorox raised theirs to 8.25% and some off-brands have followed suit) would raise the FC by around 7 ppm. If your ozonator cut the FC by 50% per day, then the FC would get to around 14 ppm FC after adding it. Since yours is higher, your ozonator may not be as powerful. You probably only need to add around 1/2 to 1 fluid ounce of bleach when you aren't soaking.

Link to comment
Share on other sites

Thanks, Chem Geek. It's a 450 gal and the bleach is 6% (says so on the bottle). I have definitely learned my lesson and won't add as much. I left the cover open for a couple hours on Sunday afternoon and FC had dropped to 16.5 by 9PM. I retested 24 hours later (cover closed, no soaking) and it had dropped to 13. So that must be my daily chlorine demand (22%). I was expecting more given the ozonator. But maybe it's not doing its job as well as I thought.

PH has also started drifting down towards normal levels. It was at 7.8 last night. I haven't added any chemicals in the past 48 hours. Hope i find FC below 10 when i test tonight.

Link to comment
Share on other sites

Update: my FC further dropped from 13 to 9 and then to 6.5 over two consecutive 24h periods (no added chemicals, no soaking). So it looks like the spa is "eating" about 3-4 ppm per day when not used. My ozonator must not be very powerful indeed. I was expecting it to use up more chlorine.

PH has also gone down to normal levels.

I'll make sure I dump around 4ppm chlorine in there every day to keep it clean. That's 4oz according to the pool calculator. I'll keep a close eye on it for a few days to make sure FC doesn't accumulate again to ridiculous levels.

Link to comment
Share on other sites

  • 1 year later...

Hi, I have a similar issue to the above original topic.

Our fibre glass spa is 1100 litres @ 37 degrees and had been empty for a while as we have been away.

For years our spa has run using Bromine and has been very stable at around Alkalinity 60-70 and PH 7.6 to 7.8 and would use 1 Bromine tablet in a floating container about every 7-9 days. We do use aeration when we use the spa which is about 1 hour per week.

When I refilled the spa a couple of weeks ago it seems to be behaving differently and is less stable, the Bromine level has now stabilized and in acceptable ranges but the Alkalinity is around 30-40 and PH level is around 7.9 or 8.0. I don't seem to be able to lift the Alkalinity as the PH level seems to jump a lot.

I am not sure how to get a better result or if this is safe to use as it seems to be aggravating our skin slightly (it maybe that we are just not used to it now).

Any ideas would on how to get back to our typical levels or whether it is okay to use at this level would be greatly appreciated.

Link to comment
Share on other sites

If you add baking soda that should raise the TA level but if you are having your pH rise a lot that usually means your TA is too high. Have you been doing something differently? You say you use bromine tablets in a floater but could it be that you used to use non-chlorine shock (MPS) on occasion? MPS is acidic so would help keep pH lower though it also lowers TA over time. Dichlor is also net acidic when accounting for chlorine usage/consumption if you've been using that as an oxidizer with your bromine.

Link to comment
Share on other sites

Thanks for the response, I haven't recently changed any chemicals in the spa. The only thing that has changed is the test kit I am using and in particular the pH testing could be a little different as I have none of the Taylors product left and i couldn't get it locally in Australia or delivered last time I did some searching. It may be that the pH test is different enough and the pH is actually at an okay level but I am not sure of this.

I have Taylors product left for the TA and FC test so I can compare them with my new test kit and they are a match so i know the levels for those are correct with the new test kit so the pH test should be close also. I added a little more baking soda and my levels are now TA 40, pH 8-8.1, FC 2.

I may need to take a sample to a pool shop to see what they think the levels are or this may be as good as I can get.

New test kit: http://www.bunnings.com.au/hy-clor-4-in-1-pool-test-kit_p3090182

Chemicals apart from baking soda are:

https://www.dropbox.com/s/5qe6qrgt8agma8f/Spa%20tablets%20small.jpg?dl=0

https://www.dropbox.com/s/2ejv9sqtn73qrrj/Spa%20chlorine%20small.jpg?dl=0

https://www.dropbox.com/s/0n9cbxij9wk4y0i/pH%20reducer%20small.jpg?dl=0

https://www.dropbox.com/s/7ieo9xlv9namls0/granular%20bromine%20small.jpg?dl=0

Link to comment
Share on other sites

The pH reducer (sodium bisulfate) will lower both pH and TA while aeration of the water will raise the pH with no change in TA. So the drop in TA is explained by your adding acid in conjunction with the aeration in your spa. I suspect you are lowering the pH too much since lower pH increases the rate of outgassing. I wouldn't lower the pH below 7.5 when you lower it. You may need to use some supplemental pH buffering such as 50 ppm Borates most easily added from boric acid. I'd add that when the TA is at around 50 ppm. Then the pH should be more stable.

Link to comment
Share on other sites

Thanks for the reply. I haven't lowered my pH below 7.5 as my TA was down around 30 at pH 7.7 and I didn't want or need to go down any lower.

Its been very stable at pH 7.9-8.0,TA 40 and FC 2 for the last week or so with a tablet in the floater.

Also I haven't used aeration when having a spa just to try and reduce unnecessary changes in the spa water.

I haven't used Borates ever before so I am unsure how much to use or how to measure the change afterwards.

I do have a 500g unopened container of Borax but it doesn't say how strong it is on the container anywhere.

How much Borax would I put in an 1100 litre spa with the above measurements and what should the subsequent results be?

I do not have a way of measuring Borates level with my current test kits.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share



×
×
  • Create New...