Katalox Light raises pH above legal limit

[GerardP]

I have a property in Scotland which has a water supply from a borehole with around 9ppm Iron and 0.3ppm Mn and a pH of 5.9. I have recently installed a Katalox Light system and this has sorted the Iron and Manganese problem but the pH has rocketed to 9.8 which is above the UK legal limit for drinking water of 9.5. The house is used for holiday letting and I have to get it officially tested and am therefore under pressure to lower the pH below 9.5.

For the last two months I have been trying to get Watch Water to help solve this problem, but just today have finally been told by them that they have only encountered this problem three or four times in the whole world. However in the same breath they tell me that their literature states that it can raise pH up to 10 so I cannot complain!! I neither saw this literature nor was made aware of it before buying the Katalox. They cannot explain satisfactorily why the Katalox has raised the pH so much and have effectively said that their Chemists are not interested in doing so as the problem is so rare and they don't have the time.

Has anyone had any experience of high pH problems with Katalox or has anyone any idea what has caused this and if there is anything I can do to correct it.

Any help would be very gratefully received.

Many thanks in advance.

Gerard

 

[Reach4]

I have a property in Scotland which has a water supply from a borehole with around 9ppm Iron and 0.3ppm Mn and a pH of 5.9. I have recently installed a Katalox Light system and this has sorted the Iron and Manganese problem but the pH has rocketed to 9.8 which is above the UK legal limit for drinking water of 9.5.

Your raw water pH is 5.9 and the treated water went to 9.8? I suspect that either you wrote that wrong, one of the tests on the water was wrong, or there was some treatment that you missed. How long has this well been in operation? Is there an injection pump in the system?

I suggest you get some pH test paper to sanity-check the numbers.

I am not a professional.

 

[Sponsor]

 

[GerardP]

Many thanks for the reply.

I'm afraid it isn't a misprint! My raw water is consistently recording a pH around 6 (as tested by a Government accredited lab) and the Katalox treated water has been tested twice by a Government Accredited laboratory and both times come it at exactly 9.8. These results also correspond to my own tests using a regularly calibrated Hanna Instrument hand held pH meter.

Originally Watch Water indicated that the reason is that the raw water has very low buffering capacity and that the negatively charged Katalox granules result in an excess concentration of Bicarbonate. However they cannot explain the chemistry in any detail other than to point me to their marketing information on their web site which I find this very incomplete and difficult to understand.

The raw water is generally good quality and comes from a 33m borehole drilled into the granite bedrock. The low pH dissolves iron and presumably some other chemicals from the local stone but apart from that is pretty good quality so the lack of buffering capacity does sound plausible.

I suggested to them that the reason could be the slaked lime which used in the Katalox. As far as I can see slaked lime has an equilibrium pH of around 12 and certainly the Calcium level has increased from 5.2mg/l to 24mg/l. However Watch Water has dismissed this reason. If it was this then I guess, once the slaked lime had been dissolved the pH would lower - this happened with my earlier system which used Calcium Carbonate to increase the pH. Watch Water do advise more backwashing in cases of raised pH which would also fit with the slaked lime being the culprit. However I've backwashed till I'm blue in the face and recorded no decrease. Also I've set the system to backwash every night and the flow rate is excellent - much better than my old BIRM based system due to Katalox being lighter)

Alkalinity is increased from 21mgHCO3/I to 76mgHCO3/l.

The only other "treatment" is a Mazzei air injector upstream from the Katalox. I commissioned the Katalox system around 20 Feb and got accurate test a few days after that and again on 30 March

I have to say that the Katalox has done a good job getting rid of the iron and manganese! Down from 9.7mg/l and 0.25mg/l to 0.79mg/l and 0.04mg/l respectively. The water is also very clear 0.8NTU.

If I could just crack the pH problem I would be very happy. It's a great shame Watch Water don't seem to know what to do.

 

[_John_]

I have certainly seen the pH of a freshly installed KL system be around 10, but usually that falls to at least 8 just after backwashing the fines out of a fresh install. I have one on my own home, but our pH stays the same before treatment and after KL/Softening (7.5).

The lowest pH we've installed one on by itself was 6.5, and it works great at that install and leaves the pH around that.

I'll be following this thread myself, as I would have thought the pH would have resolved after some use.

 

[Bannerman]

I've back washed till I'm blue in the face.

Also I've set the system to backwash every night and the flow rate is excellent -

Are you able to define the backwash flow rate, back wash duration and your tank size?

Watchwater recommends a continuous 45-60 minute back wash on the initial installation, at a flow rate of 10-12 gpm per square foot of surface area. This is to be followed by a 15 minute fast rinse at 8 gpm/ft2. (http://watchwater.com/katalox_light/documents/KL_operation_manual.pdf)

While the ongoing 5-10 minute backwash is recommended to be at 8-10 gpm/ft2, forum contributor Dittohead has tested and has established a higher backwash rate (IIRC: ~14 gpm/ft2) to be optimal.

 

[GerardP]

Are you able to define the backwash flow rate, back wash duration and your tank size?

I haven't actually measured the backwash flow, but I have measured the flow to the house at just under 3metres/hour which equates to around 13.2US Gal/min. My tank is an 1865 which gives an area of 1.75sq ft. So the house flow rate is around 7.5 gpm/ft2. I checked with Watchwater before getting the Katalox and they were happy with that as the backwash rate is liable to be at least 10 to 15% more. My pump is rated at 5.6cu metres/hr which would give a flow rate of 15gpm/ft2. Clearly, the act of pumping the water up 30 metres will lower the flow rate but I suspect the backwash rate is between the 7.5 and 15gpm/f2. I've now bought a flow meter with digital flow rate read out but haven't plumbed it in yet.

As far as backwash time goes, initially I spent the first couple of days switching on the backwash 5 or 6 times a day and did two long backwashes of at least 2 hours non stop! Additionally I've set the Fleck valve to backwash every night for 10 ins with a 6 min rinse.

I was pretty sure that backwashing is not the cause of the increased pH. The backwash is definitely removing plenty of rust before running clear and the iron level of the treated output is low and the turbidity excellent. I assumed the reason Watch Water advise extra backwashing was simply to wash out the fines which might have an effect - especially (I assumed) if they contain loose slaked lime. This is certainly my experience when using a system which used Calcium Carbonate which produced a high pH around 9.5 for a short time until all the "dust" was washed out.

Gerard

 

[Bannerman]

The back wash flow rate (DLFC = drain line flow control) is often specified on a label located near the drain line fitting. The back wash flow rate is governed by the DLFC button (washer with a specific size center hole), assuming your well pump and plumbing lines will support or exceed that flow rate.

 

[ditttohead]

This is far more common than most companies will admit to. We sell Katalox Light by the container loads and this is a common issue. We assume it is a byproduct of the binding agent but their is so much that is not understood about water chemistry that an absolute reason still eludes us. We see that in many applications the pH rise is very temporary and goes away within a few weeks. In other applications the pH rise can last for several months. The raise in pH seems "artificial" or without any power. It is easily reduced with the tiniest amount of acid. Water that is rich in certain minerals can take considerable neutralization. The Katalox Light induced pH raise takes almost nothing to bring it back down, almost as if it were induced by dissolved hydrogen rather than actual mineral buffering. We are doing some in house testing of the media to try to replicate some real world applications that can duplicate these anomalies. SO far our findings have been fairly simple, it is a pH rise that makes pH test show a high rise. Unfortunately, I have not done enough research into how to do pH testing based on actual power, rather than perception. A simple comparison is a fire made of dried pine needles compared to burning a log. The pine needles appear to burn amazingly, but they are short lived and have little actual energy, but if you were to test it at the right time, it would appear to be much more powerful than burning a log...

I know there are some guys who read this sight who have some expertise in this issue, hopefully someone will chime in with a better explanation.

As for now, continue to rinse the system. The pH rise will subside in time. but the process of air injection, reduction/oxidation etc will affect the pH of course.

 

[GerardP]

The back wash flow rate (DLFC = drain line flow control) is often specified on a label located near the drain line fitting. The back wash flow rate is governed by the DLFC button (washer with a specific size center hole), assuming your well pump and plumbing lines will support or exceed that flow rate.

I'm afraid my set up doesn't have a DLFC button. It simply pumps through the maximum it can for as long as the timer is set for. The valve is an old Fleck 2750 pre electronic. However it's served me well and I've been through 3 pistons in the 16 years it's been running.

 

[Reach4]

I'm afraid my set up doesn't have a DLFC button. It simply pumps through the maximum it can for as long as the timer is set for. The valve is an old Fleck 2750 pre electronic. However it's served me well and I've been through 3 pistons in the 16 years it's been running.

You can measure the backwash rate using a bucket of known volume, and a timer that can measure seconds.

If you don't know the capacity of the bucket, you could weigh the bucket full and empty.

If you don't have a DLFC, the flow will be more dependent on the water pressure than if you had a DLFC.

 

[GerardP]

Hi Dittohead

Thanks for this post - it fits in well with what I've been thinking and what Watch Water has told me - apart from the rarity of getting high pH!! Watch Water originally said that my water must have very low buffering capacity and this would fit in with the comment about needing very little acid to bring the pH down.

I've just had an email from Watch Water kindly offering to take my Katalox back because it isn't working but I'm actually quite keen to keep it if I can sort out the illegal pH level. Apart from the high pH I'm vey happy with it. The iron, manganese and turbidity levels are all nice and low. These are all areas that my old Triplex System (the UK's answer to Terminator Plus system I think) could not cope with and I did test out another BIRM type media with only slightly better results. I've asked them to try and give me some help.

I still think that their slaked lime might be part of the cause. The Material Safety Data Sheet gives Calcium Hydroxide as an ingredient (>5%) and passing through the media has increased Calcium levels by 4.6 times.

If there is anyone reading this who has knowledge of this area of water chemistry and could give me advice I'd be really grateful. Would some form of acid injector be feasible or will the problem more than likely sort itself out in the next few months?

Gerard

 

[ditttohead]

Are you sure it is a 2750? Fleck made many valves that look almost identical.

As stated above, we must know the DLFC rate, this is critical for the system to operate properly.

 

[GerardP]

You can measure the backwash rate using a bucket of known volume, and a timer that can measure seconds.

I'll measure the next time I'm up at the house which will be next weekend.

If you don't have a DLFC, the flow will be more dependent on the water pressure than if you had a DLFC.

The backwash is at the maximum the pump will deliver. My only way to increase the rate would be to bypass the Mazzei Air Venturi as the constriction in the Venturi will increase flow resistance. There is a bypass but the mazzei unit will impose some friction and there will be some back pressure introduced from the bypass check valve.

As I said in an earlier post I reckon the backwash flow must be greater than 7.5 and less than 15gpm/f2. I suspect it's appreciably above the 7.5 figure as a lot more air is drawn through the Mazzei unit during backwash than normal use indicating the flow is much better.

Are you sure it is a 2750? Fleck made many valves that look almost identical.

Yes, it's definitely a 2750 with a Non Bypass Piston and a 3200 Timer.

Reach4 and Dittohead and Bannerman

I'm interested in your thoughts as to why backflow rates will have an effect on the pH.

Gerard

And by the way, many thanks for your interest and help in this. It really is much appreciated

 

[Reach4]

I'm interested in your thoughts as to why backflow rates will have an effect on the pH.

The folks are saying that your effect would probably disappear after enough back-washing. It takes a certain amount of flow during backwash to rinse, fluff and re-distribute the KL. If your backflow was low, that would seem to prevent a normal backwash.

 

[Bannerman]

The raise in pH seems "artificial" or without any power. It is easily reduced with the tiniest amount of acid

Dittohead, in consideration of what you had stated, would a 3-5 minute high volume flush of the plumbing lines prior to obtaining a test sample, tend to provide a more accurate pH reading?

Could the pH be altered by sitting for a time in the home's plumbing lines? (ie: water not having as long contact time with the plumbing lines, may have a lower pH value?)

but the process of air injection, reduction/oxidation etc will affect the pH of course.

Perhaps Gerrard should then discontinue use of the air injection system to determine what type of change if any, that will have on the pH reading.

 

[WellOff]

Bannerman triggers an important question here: what kind of piping is in use?

I know that my poly and PVC distribution lines tend to build up a bit of crud and I have to periodically shock them.

For water testing, however, I have spigots that are within the treatment/filter system (to take various samples along the system's processing) and one right at the end of the system and before the feed to the distribution line to the house.

The following document talks about water chemistry effects on piping, though most issues tend to revolve around lower pH values (maybe someone smarter than I can find something that could be a concern with high pH values such as that OP is experiencing):

http://www.water-research.net/index...sive-water-lead-copper-aluminum-zinc-and-more

 

[Reach4]

Perhaps Gerrard should then discontinue use of the air injection system to determine what type of change if any, that will have on the pH reading.

Interesting idea. Perhaps he could throttle back the air a bit to get under the target.

If somebody could control this pH-raising phenomenon, that could be really useful to people with low pH and iron.

I had considered what might happen if he fed some pH 9.7 water to the pH 6 incoming water, but after thinking about it, that probably would be worse. And if he mixed 5% pH 6 feed water with pH 9.7, that would bring down the pH, but it would give 0.45 ppm iron, which would be not nice. Sigh.

After some more backwashing, lets hope the pH drops below 9.5.

 

[GerardP]

The folks are saying that your effect would probably disappear after enough back-washing. It takes a certain amount of flow during backwash to rinse, fluff and re-distribute the KL. If your backflow was low, that would seem to prevent a normal backwash

The system was originally designed for a BIRM/InterAg/Calcite mixture which I think is substantially heavier than Katalox. Katalox is only marginally heavier than water and so backwashing quite easily lifts and expands the bed thus allowing the dust and fines to wash out. When I installed the Katalox I was immediately struck by the greater backwash flow out the drain. I'm pretty confident that all the debris is washed out but I'll measure the rate next week when I'm up and report back the actual backwash rate. It won't be the first time I've confidently predicted something only to be proved wrong!

Dittohead, in consideration of what you had stated, would a 3-5 minute high volume flush of the plumbing lines prior to obtaining a test sample, tend to provide a more accurate pH reading?

Could the pH be altered by sitting for a time in the home's plumbing lines? (ie: water not having as long contact time with the plumbing lines, may have a lower pH value?)

Interesting thought. Does anyone have an idea of the chemistry involved if this were the case. My pipes are all drinking water quality plastic pipes up to the house and the kitchen tap is only a meter away from where the plastic stops. The first sample I took was down at the pump house taken from a sample tap located just after all the treatment stuff. The second sample taken a month later was taken by the Government tester who took it from the kitchen tap but after running the tap for a few minutes so none of the sample would have lain in the copper pipe but could have lain in the plastic pipe for a bit. I'll take a third sample next week and get it tested just in case another month has resulted in a change as suggested by Dittohead.

but the process of air injection, reduction/oxidation etc will affect the pH of course.

Interesting idea. Perhaps he could throttle back the air a bit to get under the target

It would be interesting to test the effect of this. I would need to do a bit of plumbing to bypass the Mazzei venture and Air cylinder and then run the system long enough to ensure all the aerated water was expelled. (I'd not be too keen to adjust the Mazzei bypass valve which effectively regulates how much water flows through the Venturi and therefore how much air is sucked in as I know it's incredibly fickle and I might have a real hard time adjusting it back to the correct setting!) Not sure I'll have time for that on this visit but if the problem persists I will maybe test it out later. Somewhere in the Watchwater website it does say that blowing air through the water blows out CO2 thus increasing pH.

Thanks again to all contributors for your interest and help on this.

Gerard

 

[Bannerman]

so none of the sample would have lain in the copper pipe but could have lain in the plastic pipe for a bit.

Perhaps I should have expanded my question to include water that has had long contact with the Katalox media. The KL filter tank would contain a substantial amount of water that is in contact with the media when no water is being drawn. Since the property appears to be a vacation residence, water will be sitting in the KL tank for excessively long period so maybe the water should flow for 20 minutes each visit initially, to refresh the entire storage, filter & distribution system.

My take on Dittohead's comment about the pH rise being 'artificial' and 'without power', to imply the pH is easily reduced and possibly will reduce with higher velocity service flow and/or system flush.

I'd not be too keen to adjust the Mazzei bypass valve which effectively regulates how much water flows through the Venturi

Maybe you could temporarily, easily block-off the air inlet port to the venturi without making any adjustments? Tape? Short sheet metal screw? Chewing gum?

 

[WellOff]

OK... continuing on my efforts to contribute by way of musing:

http://www.lowrycg.com/wp-content/uploads/2013/05/Using-Air-and-Acid-to-Get-Perfect-pH-and-Alk.pdf

This seems to imply that injecting air contributes to raising pH.

My scope of knowledge is mostly centered around my system. I am a strong proponent of H2O2 (it's necessary in my case). Looking up H2O2's affects on pH is pretty interesting:

http://www.h2o2.com/faqs/FaqDetail.aspx?fId=26

Basically, according to that article, H2O2 solutions are of a lower pH. Interesting because in one case adding O2 increases pH while adding it in the form of H2O2 can lower pH. Buffering difference? (water in H2O2 has more buffering?)

And then there's this:

http://www.pondkoi.com/water_quality.htm

That article presents the importance of buffering. And I believe that the issues that the OP is having can only be affected from a buffering angle. The fact that the water's pH is easily changed has to do with buffering; in this case, a lack of. But based on the minerals that are in the raw water I'm confused as to how it couldn't have reasonable buffering capacity.

Is there any way that one could readily (without a lot of effort) plumb in a different water feed-stock here?