Yet another "how do I keep my pH from going up"

[Yoav]

Hi All.

I have to balance my pH every day or two. It goes from 7.2 to 7.5 in about a day and to ~7.7 the next day.

Factors I am aware of that increase pH:
1. Bathers - the effect above occurs with or without bathers
2. Air leak in my piping - aeration as I understand it should not contribute that much of an increase
3. Daily Sodium Hypochlorite dose of ~300 cc(ml) [planning to get a liquidator at some point]
4. My fill water's TA is very high (>180) - the effect above occurs even if I do not top up. (I do use a bucket of water per chlorine or acid dose but that should be insignificant)

Anything else I am missing here? how much of a pH increase does the bleach account for?

My pool's TA is around 40. I am keeping it low since to my understanding higher levels will only offset my pH problem.
The recent frustration with pH increases got me thinking - something with the BBB method doesn't make sense to me. Soda Bicarb is used to buffer pH but it seems to me that this buffering is one sided. It has prevented my pH from going down but not from going up (that is assuming the buffering effect should work symmetrically around a pH of 7)
If that is the case, then using Bicarb with Bleach is not a good thing. Am I missing something?
If not, is there a buffer for preventing pH from rising?


Appreciate the help,
Yoav.


Some background information:

For anyone who is familiar with my previous posts - pertinent info since I last posted:

1. I still have a problem with my suction side pipe, but am using an alternate pipe for circulation. (some air is still leaking into the system). Should have it fixed soon I hope.

2. I had my (fiberglass) pool resurfaced

3. I refilled my pool about a month ago.

4. My current working method for balancing water is basically Hydrochloric acid to balance pH, Sodium Hypochlorite 12.5%, and no CYA.
Pretty much into a routine that works well, and my water seems to be doing fine for a change.
The downside of 0 CYA notwithstanding, using chlorine without a buffer is a real pleasure.

 

[meatloaf]

I have the same problem. PH rises from 7.3 to 7.5 each day. I use approx 14 oz of 10% bleach per day and add approx 8 oz of 31.5% MA daily. TA is 60 - 65, CH is 600 and CYA is approx 65. CSI index is about -.14.
I don't have any waterfalls turned on and the water is perfectly clear. Water temp is topping out at about 94.5*. I've just been dealing with the addition of MA daily until I find the answer.

 

[chem geek]

300 ml of 12.5% chlorinating liquid in 15,000 liters would raise the Free Chlorine (FC) by 2.5 ppm which sounds about average for a pool exposed to sunlight through most of the day (a higher CYA level could have a lower chlorine loss). Just out of curiosity, what is your CYA level? You write that it is zero, but that doesn't make any sense. From your earlier posts it sounds like you were keeping it lower so you could have a lower FC due to swallowing of pool water by your kids and we had some discussion about that. If your CYA was truly zero, then you would lose around half the FC every hour around noontime in direct sunlight. Even if you want a lower CYA level, you should have some so that the active chlorine level is not too strong. How are you measuring the CYA level? I doubt very much that its zero if you are only using 2.5 ppm FC per day (unless the pool isn't in much direct sunlight). You simply cannot maintain 0.1 ppm FC in a pool with no CYA which is roughly what you would need to do to be equivalent to 3 ppm FC with 30 ppm CYA, for example. If you are concerned about health, then you don't want to have no CYA in the water at all since the higher active chlorine level is far more reactive and oxidizes skin, swimsuits, hair, etc., corrodes faster, and likely produces more nitrogen trichloride.

If the pH of your chlorinating liquid were high, such as 13.5 instead of 12.5, then that could cause a rise in pH of around 0.1 per day (starting at a pH near 7.5). So while that might account for part of your rising pH, it certainly isn't all of it. Do you have some sort of Material Safety Data Sheet (MSDS) equivalent that gives the pH of your chlorinating liquid?

The fact that the pH rises from 7.2 to 7.5 more quickly than from 7.5 to 7.7 does seem to indicate that carbon dioxide outgassing is part of the pH rise since 7.2 to 7.5 would require over twice as much base (such as "excess lye" from bleach or chlorinating liquid) as going from 7.5 to 7.7. The rate of carbon dioxide outgassing, however, is much higher at 7.2 than at 7.5 and 7.7 (as shown in this chart). What is unusual is that at a TA of 40 the outgassing is usually very low even with aeration. Did you find that the amount of acid you need to add got reduced in any way as the TA dropped (the rate of pH rise may have not dropped as much)? Are you sure your TA is really 40 ppm -- how are you measuring this? How did you lower the TA level?

If your pool was freshly replastered, then that would be a significant source of pH rise, but you have a fiberglass pool and I don't think that its resurfacing has any calcium carbonate, though maybe it contains some chemicals that could lead to some pH rise (I don't know), but would expect that to slow down over time.

If I were to hazard a guess, I would say that your TA, CYA and maybe even FC measurements are all off. Since you probably cannot get a Taylor K-2006 test kit in Israel, can you at least get a Palintest SP 315C which is like the K-2006 except for the chlorine test (it's DPD) and maybe the separate Palintest SP 300 which is a FAS-DPD chlorine test?

The pH buffering of the carbonate buffer system is not symmetrical around 7.0. It buffers more strongly as the pH falls from 8.2 to 6.2. However, the carbonates are also a SOURCE of rising pH since higher TA leads to more carbon dioxide outgassing that raises the pH. For additional pH buffering that does not contribute to carbon dioxide outgassing and is not a source of rising pH one can use 50 ppm Borates in the water (see Adding Borates -- Why and How). The Borates buffer system buffers more strongly as the pH rises towards 9.1. Technically, by itself with no other changes (such as lowering the TA) the boreates will slow the rate of pH rise, but will not change the amount of acid needed to be added (you add more quantity when you add it, but you add it less frequently).

 

[chem geek]

I have the same problem. PH rises from 7.3 to 7.5 each day. I use approx 14 oz of 10% bleach per day and add approx 8 oz of 31.5% MA daily. TA is 60 - 65, CH is 600 and CYA is approx 65. CSI index is about -.14.
I don't have any waterfalls turned on and the water is perfectly clear. Water temp is topping out at about 94.5*. I've just been dealing with the addition of MA daily until I find the answer.

Instead of bringing your pH down to 7.3 each time, what happens if you let it rise to 7.7 or 7.8 and then just lower it to 7.5? This may use less acid and if it does then that's because the pH rise is from carbon dioxide outgassing even with your lower TA level. You could try lowering the TA further and/or using 50 ppm Borates though the latter would probably only let you add acid less frequently and not change the total amount of acid you need to add (though some people find it does lower total acid amounts needed). If you do end up with a higher pH target, then you'd need a lower CH level and perhaps your fill water is high in CH (I notice you had possible calcium scaling problems in your earlier posts so were keeping the pH lower to avoid that).

I noticed in the photos of your pool that you have a dual aerator and a fountain -- are you using those to help cool off the pool water? If so, then that could lead to more pH rise.

14 fluid ounces of 10% bleach in 10,500 gallons is only around 1 ppm FC per day which is very low and doesn't make sense since it appears that your pool is outdoors and in direct sunlight (is that correct?), especially in Arizona. Do you use a mostly opaque pool cover (if so, in Arizona I'd expect that to be white or reflective so that the water doesn't get too hot)? What is your FC level when you add chlorine each day? This low chlorine usage does not make sense.

 

[teapot]

On purely a mechanical side you have quite a big pump (3/4 hp) for a relatively small pool (4000 US gallons) so your water is really moving which could be causing a PH rise on it own.

 

[dmanb2b]

2. Air leak in my piping - aeration as I understand it should not contribute that much of an increase

My pool's TA is around 40.

3. I refilled my pool about a month ago.

Air leak/aeration can rasie PH significantly as teapot mentioned

How are you testing TA? Is it a drop based kit?

How did you lower TA from 180 to 40? Keeping TA at 40 can make thing just as unstable as TA of 120+. Try raising your TA to 50. Baking soda/Soda Bicarb raises TA, with a much lower effect on PH.

 

[meatloaf]

meatloaf wrote:
I have the same problem. PH rises from 7.3 to 7.5 each day. I use approx 14 oz of 10% bleach per day and add approx 8 oz of 31.5% MA daily. TA is 60 - 65, CH is 600 and CYA is approx 65. CSI index is about -.14.
I don't have any waterfalls turned on and the water is perfectly clear. Water temp is topping out at about 94.5*. I've just been dealing with the addition of MA daily until I find the answer

Sorry, I meant to write 24 oz of 10% bleach per day. I'll try maintaining PH @ 7.4 for a while and see if that helps. Also I have not been using the fountain or aerator.
Thanks

 

[Yoav]

Wow. Thanks for all the feedback. I'll try to answer all the points raised.

Richard, I see you remember our discussion.

0 CYA
--------
First - what is Nitrogen Trichloride? I haven't encountered it yet.
I say I have 0 CYA simply because I haven't put any in the pool. After refilling it, I have used only Sodium Hypo. I decided to avoid CYA altogether simply because with CYA my water always got shot, and I lack the ability to test FC over 3 ppm which is required for almost any reasonable CYA level.
Israel is extremely hot and sunny which means I lose effective FC during the first couple of hours of daytime.
Basically I decided I will use the "grandma approach". That would be the occasional rubber tub the kids can thrash about in the back yard after which the water is tossed out. Chlorine is never used for such stuff, so I decided to approximate that model. I use 2 ppm of chlorine in the evening to kill whatever is in the pool. The FC is gone by late morning. Sometimes I drop a bit (50 cc) into the pool if I know ahead of time that they will be using it. So basically, when they use it, there is very little if any chlorine in the pool. Reading your post has me worried again, both about bacteria and about chlorine being very aggressive with no CYA.
I have to think some more about this. I should not use more than 20 ppm of CYA in any case, and I am not sure that 20 ppm would provide any significant FC protection in our sunny region. As for our health and protection (from FC), if I do get a feeder that maintains a constant FC level, I guess I would want 20 ppm of CYA in the pool.

Measuring water chemistry
---------------------------

pH - Palintest Phenol Red tablets. An ExTech pH digital meter
FC - Lovibond DPD #1 tablets
CC - Lovibond DPD #3 tablets
TA - Aquachek strips (very inaccurate)
CYA - do not measure it as I did not put in any.

Pool:

pH 6.8 (Phenol)
FC 0 (DPD)
TA 40 (Aquachek strip)

Fill water:

pH 7.57 (ExTech)
pH 7.6 (Phenol)
pH >7.8 (Aquachek strip)
FC 0 (DPD)
TA >180 (Aquachek strip)

Liquid chlorine pH
------------------

Thanks for giving me an idea as to what to expect. I will try to get an MSDS though I do not have such high hopes they have one or disclose their supplier.
Adding Muriatic Acid on a regular basis is something I would like to avoid. It is a dangerous chemical and I have no way of handling it properly. That is why:
1. I pour it into a bucket of water to thin it out,
2. I do so directly from the jug for lack of an appropriate measurement utensil
3. I don't know exactly how much I pour in. I have a knack of getting the right amount to reach my target pH. The worst that could happen is I wait a bit and the pH magically increases

Lowering TA
-------------

I never actively lowered it. I think its the high frequency of acid doses that brought it down over the last 2-4 weeks.
As mentioned above, I use test strips for measuring TA which (in my hands at least) are quite inaccurate.

Palintest kits
-------------

Darn! I haven't heard of Palintest kits before!
I went through a lot to try to get my hands on a TF-100 or a Taylor K-2006, but until I find the resources to import >1000 kits, my hands are tied.
I will get right on it and try to find out if the Palintest kits are somehow available here.

pH buffering
------------

It always amazes me how much I still have to learn. I don't know about the chemical processes involved in pH rising, nor carbon dioxide outgassing.
I will get started on my reading on this subject.

teapot:
--------

This is something that has been baffling me for quite a while. I've noticed the relatively small pump/volume ratio that many of the forum members have compared with mine, yet I can't shake the feeling that my flow is not strong enough both on the return and on the skimmer. But then I always felt that since I don't have a main drain on the bottom, my water isn't properly circulated... but that is for another post.
When you say "the water is really moving" do you mean to say that it is flowing visibly? do you mean that the rising pH is due to aeration as a result of moving water or is there another effect you are referring to?

dmanb2b:
-----------

As I've mentioned above I did not actively lower the TA and I'm sorry to say I do not have an accurate way of measuring it. I believe that frequent acid doses simply brought it down - a process I did not counter since I assumed I need it as low as I can get it.
Do you mean that raising the TA a bit could buffer and slow down the rising pH?

 

[chem geek]

First - what is Nitrogen Trichloride? I haven't encountered it yet.
I say I have 0 CYA simply because I haven't put any in the pool. After refilling it, I have used only Sodium Hypo. I decided to avoid CYA altogether simply because with CYA my water always got shot, and I lack the ability to test FC over 3 ppm which is required for almost any reasonable CYA level.
:
Do you mean that raising the TA a bit could buffer and slow down the rising pH?

I'm going to guess that to get from 7.5 to 7.2 pH you add around 80 ml of full-strength Muriatic Acid (31.45% Hydrochloric Acid) every day on average. That would lower the TA by 2.7 per day so almost 20 ppm per week and could account for some of the drop in TA depending on how long you've been doing this.

You won't be able to test Nitrogen Trichloride -- it's usually associated with nasty "pool smell" though that can also be monochloramine or dichloramine. I'm just saying that more of the nitrogen trichloride is produced when the active chlorine level is higher and that happens when you use chlorine with no CYA in the water. This is just bad to do for multiple reasons as I had indicated -- you don't want the active chlorine level to be high and you don't want your chlorine to break down so quickly in sunlight either. You should have SOME CYA in the water even if you can't measure more than 3 ppm FC with your test kit. You should be able to get a DPD test kit that measures to 5 ppm even if you can't get the truly spectacular FAS-DPD test kit. Anyway, if you had 30 ppm FC, then you could maintain 3 ppm which would be quite reasonable and this WOULD protect chlorine breakdown from sunlight more than you have right now -- instead of losing half the FC in an hour, you might lose 50-60% over one day instead which is obviously much better. That does mean going to around 4-5 ppm FC and having it drop to 2-2.5 ppm or something like that. I don't think that 20 ppm CYA will be as practical since the chlorine loss will be higher and many CYA test kits only start at 30 ppm (some test down to 20 ppm). You can use The Pool Calculator to calculate dosages.

Your other option to have a low FC but have protection from sunlight would be something like 2-3 ppm FC with 80 ppm CYA plus some supplemental algaecide protection at extra cost. There is no great solution here, however. PolyQuat 60 added weekly might work, phosphate removers might work if you don't have organic phosphates in the water, copper could work but could also stain, and 50 ppm Borates might work but you've already got concern for your kids swallowing the water. Also keep in mind that with the small size of your pool the effective bather load is higher and if you kids urinate then they could wipe out the lower FC levels.

Note that if you are truly replacing the water each time, then your "fill, then sanitize, let chlorine drop and have kids use" approach you outlined is OK and the only thing you don't get is prevention of person-to-person transmission of disease primarily through the fecal-to-oral route, but odds are your kids may be sharing such diseases anyway and if one gets diarrhea the other would probably get it anyway unless you kept them isolated. It's more like taking a communal bath. However, if you aren't going to be replacing the water after each use, then the FC/CYA approach I outlined above would be better. If you want to split the difference, then you could be more like a spa and just use some Dichlor powder for chlorine which gives you both FC and some CYA for each one-time use. Even with keeping the pool water you could use Dichlor initially to build up the CYA level (33 ppm FC cumulatively added from Dichlor gives 30 ppm CYA) and then switch to bleach or chlorinating liquid OR you could add pure CYA initially instead -- up to you.

As for your TA level, who knows what it really is since test strips aren't that accurate. I don't think 50 ppm will be any better than 40, but you can certainly try things to see if it helps.

 

[Yoav]

You won't be able to test Nitrogen Trichloride -- it's usually associated with nasty "pool smell" though that can also be monochloramine or dichloramine.

I am happy to say that since the last time I refilled (i.e resurfaced, refilled, and stopped using anything other than bleach and muriatic acid) my water has been looking, feeling and smelling great.

Your other option to have a low FC but have protection from sunlight would be something like 2-3 ppm FC with 80 ppm CYA plus some supplemental algaecide protection at extra cost.

I've been down that road twice and will probably never go there again.

Note that if you are truly replacing the water each time, then your "fill, then sanitize, let chlorine drop and have kids use" approach you outlined is OK and the only thing you don't get is prevention of person-to-person transmission of disease
<...snip...>
It's more like taking a communal bath. However, if you aren't going to be replacing the water after each use, then the FC/CYA approach I outlined above would be better.

This has me a bit confused. Replacing the water is not an option for me. Assuming that "communal baths" are OK, how is sanitizing overnight different from replacing the water, biologically speaking?

 

[chem geek]

Replacing the water is not an option for me. Assuming that "communal baths" are OK, how is sanitizing overnight different from replacing the water, biologically speaking?

I misunderstood your "grandma approach" thinking you were tossing the water out after every use. That's when I referred to communal baths, if you were to replace the water each time it's like taking a bath but with more than one person. Since that is not the case and since you don't want to use a higher CYA level with algaecide, then the lower FC still should have CYA in the water. Otherwise it's not only too strong, but won't last long enough and will get towards zero which will be bacteriologically unsafe. So just target a lower CYA level such as 30 ppm which will at least give you some protection from sunlight and will also moderate chlorine's strength while still letting you have chlorine in the 2-4 ppm range. You will have to add chlorine at least once a day, but at least it won't get to zero and the active chlorine level won't be too strong.

 

[Yoav]

Richard, you have outlined 3 options that are safe:
1. High CYA, FC + algaecide
2. Low CYA and FC + frequent chlorine dosing
3. Communal baths - i.e fresh water with 0 FC

The 3rd approach I understand is not as safe as the first two but in my case where its only the kids bathing, it should be good enough.

I would like to take a moment and consider the communal bath approach.
I am trying to understand the difference between using fresh water in a communal bath scenario and what I am doing now (which is: hit the pool with 2 ppm overnight, and let the kids play in the pool during the day when FC is sure to be close or at 0 as a result of direct UV exposure)

I can think of two differences:
1. Fresh tap water is more sanitary than what my overnight 2 ppm FC can achieve.
2. There is a very small -and impractical - window of safe bathing time after FC drops to nearly zero.

 

[chem geek]

Fresh water from a tap is typically chlorinated, assuming it is drinking water and that's what I am assuming you are using. The water will typically either have chlorine in it or monochloramine, either of which inhibit bacterial growth. However, bacteria grow quickly so if you were to either fill a bath or have a regularly chlorinated pool get to zero FC, then any introduced bacteria could start to reproduce doubling in population every 15-60 minutes. This is somewhat analogous to having a chicken sit out on a counter for too many hours -- you can get sick eating it.

So if you treat this like a bath, fill it up, swim within an hour or two, then change the water, then this is relatively sanitary except for the person-to-person risk I wrote about earlier that is more of a concern in a commercial/public pool where one person can infect hundreds (and they typically aren't in the same family with other infection routes). It's not great, but not a disaster and people take baths all the time (though usually only one person at a time).

If you were to have FC in the pool most of the time except for just before your children swam and then added chlorine as soon as they left the pool, then this would be fairly similar to the bath approach. There is the small risk of some biofilm formation, but if you don't wait too long with the FC at 0 then that risk is fairly low since the next blast of chlorine will usually kill off what is there (in a bathtub, one drains the water so that's different for that reason). This approach of mostly chlorinating the water except for a relatively brief time of swimming is somewhat similar to what many people do in hot tubs where they add chlorine after a soak such that there is a small residual FC when they start a soak, but that gets quickly used up during the soak so they really have zero FC during much of the soak, but then add chlorine afterwards. It's not as ideal as having a measurable FC during the entire soak, but it's better than not chlorinating at all.

So I'm not going to say that what you are proposing is as safe as the normal approach of maintaining chlorine in the pool, but it is certainly better than not chlorinating at all or using certain kinds of alternative sanitizers, some of which don't inactivate viruses for example (i.e. metal ions).

Note that the above discussion was about pathogen growth, and not algae inhibition. In spas, algae isn't normally an issue since the water is so hot and there is very little sunlight, but that's not the case with your pool. So your having a period of time with low to zero chlorine has to be kept limited to prevent algae growth. That is, you can't "slide into" the near-zero chlorine level when your children enter the pool -- if the FC/CYA ratio is too low prior to your children getting into the pool, algae could grow. In practice, algae grow more slowly taking 3-8 hours to double so you'll probably be OK. I still think you need to use CYA in your water since it will be very, very hard to control your chlorine level when exposed to sunlight and you don't want it to get too low for too long. Personally, I wouldn't bother with all of this and would just do the normal chlorination route, but of course it's your pool and up to you what to do with it.

 

[Yoav]

Thanks for bearing up with all of my questions. This is really intriguing!
Perhaps I will try to get some bacterial and or algae growth test kits and perform some experiments (not in the pool of course though measuring the pool's patterns would be great too)

Since my tap water seems to contain 0 FC (tested with DPD), I'm assuming there are several methods for sanitizing drinking water. Any ideas on how they might be doing it? (the weather here is between hot to very hot 8 months a year)

 

[chem geek]

Since my tap water seems to contain 0 FC (tested with DPD), I'm assuming there are several methods for sanitizing drinking water. Any ideas on how they might be doing it? (the weather here is between hot to very hot 8 months a year)

If they are using monochloramine, then this won't show up as FC, but rather as Combined Chlorine (CC) so did you test for that as well?

 

[teapot]

teapot:
--------

This is something that has been baffling me for quite a while. I've noticed the relatively small pump/volume ratio that many of the forum members have compared with mine, yet I can't shake the feeling that my flow is not strong enough both on the return and on the skimmer. But then I always felt that since I don't have a main drain on the bottom, my water isn't properly circulated... but that is for another post.
When you say "the water is really moving" do you mean to say that it is flowing visibly? do you mean that the rising pH is due to aeration as a result of moving water or is there another effect you are referring to?

1. I still have a problem with my suction side pipe, but am using an alternate pipe for circulation. (some air is still leaking into the system). Should have it fixed soon I hope.

The average 3/4hp pump would move 10m3 /hour sufficient for a 40,000 litre pool. You have 15,000 litres so you are turning your water over in roughly 1.5 hours so it could be possible that all that movement could be raising your PH too, some oxygen bubbles are too small to notice in moving water. If you could slow down the flow by 50%-62% so you have a 3-4 hour water turnover rate then carried out your PH check it may improve the situation. I would be interested in the result too.

 

[Taz]

At the risk of a newbie spouting nonsense, but would installing an ozone generator for such a small pool (and a high turnover-rate) help? I understand there is no residual impact but with Yoav's strong feelings on chemicals ....

(edit) Not that this deals with rising PH.

Cheers - Taz

 

[Yoav]

If they are using monochloramine, then this won't show up as FC, but rather as Combined Chlorine (CC) so did you test for that as well?

I just did the test, and my results are inconclusive. My working assumption is that the procedure remains the same - first a DPD #1 tablet is dissolved, then a #3.
The problem is with measuring small amounts. Using the FC colour scale is useless in the area of 0.1 ppm, So I tried looking at the column of water from above, just to see if there is a tint of red in there. I used the same procedure with distilled water as a reference.
All I can say is that where the distilled water was an opaque column, the tap water after a #1 and #3 tablets was opaque with a very slight tint of red. Differentiating between the red tints of #1 and #3 tablets was beyond me.
If there is any FC or CC in my tap water, it must be in a very small concentration indeed.

Given this new (albeit inconclusive) information, reconsidering my original question about the difference between sanitized pool water and tap water - it sounds that there isn't much of a difference. Based on your posts about chlorine's aggressiveness without CYA, and assuming that CYA is not used in drinking water treatment, then the chlorine levels should indeed be very very low.
So basically I am drinking pool water that (I am guessing) has been filtered to a very fine degree.

Just had a thought of contacting the water company and asking them about their sanitation and filtration procedures... I wonder if they will be cooperative or defensive...

 

[Yoav]

The average 3/4hp pump would move 10m3 /hour sufficient for a 40,000 litre pool. You have 15,000 litres so you are turning your water over in roughly 1.5 hours so it could be possible that all that movement could be raising your PH too, some oxygen bubbles are too small to notice in moving water. If you could slow down the flow by 50%-62% so you have a 3-4 hour water turnover rate then carried out your PH check it may improve the situation. I would be interested in the result too.

I wish I could slow it down just to see if it works! I have no idea how to do it though. My pump is not a dual/multi-speed pump and using the intake valve to restrict the suction side flow makes my pump very unhappy...

Anyone try to connect their pump to the mains through a Variac ??? (I'm afraid I'll mess it up...)

 

[Yoav]

At the risk of a newbie spouting nonsense, but would installing an ozone generator for such a small pool (and a high turnover-rate) help? I understand there is no residual impact but with Yoav's strong feelings on chemicals ....

(edit) Not that this deals with rising PH.

Cheers - Taz

Hey Taz, what would the Ozone generator help with?